UNIVERSITY ON NAIROBI FACULTY OF …mechanical.uonbi.ac.ke/sites/default/files/cae...iv DEDICATION...

i

UNIVERSITY ON NAIROBI

FACULTY OF ENGINEERING

DEPARTMENT OF MECHANICAL AND MANUFACTURING

ENGINEERING

FINAL YEAR PROJECT

PROJECT CODE: SMK /01 /2015

TITLE: DESIGNING OF SUNFLOWER SEEDCLEANER

UNDERTAKEN BY

LENTOIMAGA EMMANUEL LERENTEN

F18/29985/2009

LANGALI MICHAIAH MAWENGO

F18/29870/2009

SUPERVISOR: MR SM KABUGO

Project report submitted in partial fulfillment of the requirement for

the award of the degree of Bachelor of Science in Mechanical

Engineering of the University of Nairobi.

Submitted on: April, 2015

ii

DECLARATION AND CERTIFICATION

We declare that this our own original work and to the best of our knowledge and has never

been presented elsewhere for academic purposes.

LENTOIMAGA EMMANUEL LERENTEN

F18/29985/2009

………………………………………………..

LANGALI MICHAIAH MAWENGO

F18/29870/2009

…………………………………………….

This project report has been submitted for examination with my approval as university

supervisor for the award of the degree of Bachelor of Science in Mechanical Engineering.

Sign:

……………………………………………..

Date:

……………………………………………..

Supervisor:

Mr. S.M Kabugo.

iii

iv

DEDICATION

We would like to dedicate this report to our parents who brought us to this world and

supported us throughout our lives, and to all those who have been inspired by fabrication,

designing and chose to pursue it as their source of income and career, also to all the

upcoming design and fabrication companies.

v

ACKNOWLEDGMENT

First and foremost, we as the authors wish to thank our family and friends who have

supported us throughout our life. We also wish to thank all of our previous and current

academic aspirators who have guided us to this point in our academic career. Lastly, we as

the authors would like to thank our peers in the department of mechanical engineering at the

University of Nairobi who were always willing to share their extensive knowledge of design

work and fabrication of machines this includes all those involved in the conception of this

idea.

We would also like to thank the almighty God for sustaining us throughout this undertaken

and for giving us everything we call ours. We express our sincere appreciation to

Mr. S.M Kabugo for his guidance, advice, criticism, systematic, supervision, encouragement

and insight throughout this project.

vi

ABSTRACT

The objectives of the project was to look at different types of methods and machines used for

seed cleaning purposes and hence Design and if possible fabricate a simple sunflower seed

cleaner that is both cost effective and efficient.

A literature review of the research and processes involved in sunflower seed cleaning was

done highlighting the different types each of the major processes and the different types of

equipments used to perform this processes. They are discussed in detail in the chapter one of

the project report as well as the specialized equipment used in the seed cleaning machines

which are discussed in depth in chapter two. This completed the first part of the project,

which enables us to come up with a questions on what entailed a simplified fabrication of a

seed cleaner and how each component is designed, thus enabling us to start off the second

part of the project which was on survey of the market on available components within and

outside our country if necessary and on the cost of each components in the fabrication

industry.

From the research done and the background knowledge on the literature review done, a

conclusion was drawn highlighting the problems and possible solutions we were to face and

overcome when doing the design for the sunflower seed cleaner.

In this report we looked at key design parameters as per industry standards and recommended

practices for use in large/medium/small scale farming depending on the accessibility of

materials and also affordability.

vii

NOMENCLACTURE:

PARTS SYMBOLS AND ABREVIATIONS

SHAFT

(Horizontal):

-shear stress due to torsion

T- Torque on the shaft/spring

N- Revolutions per minute Hp- horse power in kilowatts - Bending stress

M- Bending moment at the point of interest

-Outer diameter of the shaft - Axial stress

- Axial force (tensile/compressive)

- Column-action factor (=1.0 for tensile load)

L – Length of shaft - Yield stress in compression

- Maximum normal stress - Torsion factors

-Bending factors

SPRINGS;

- Shear stress due to torsion

- Shear stress due to force F

D – Mean diameter of spring d – Diameter of coil wire - Polar moment of inertia

- Wahl correction factor

N – Springs number of active turns G – Modulus of elasticity

F – Force - Deflection

FANS AND

BLOWERS:

-Total pressure of a fan

- Velocity pressure of a fan - Static pressure of the fan

- Static efficiency

- Mechanical efficiency

Ov- Dynamic pressure /Outlet velocity -Density altitude above sea level

V – Local velocity Q- Volume of air

A – Duct area - Minimum hub diameter

- Minimum wheel diameter

BkW - Brake (shaft) kilowatt of Fan in (kilowatts, kW);

D -Wheel Diameter, in (m);

d-Relative Density, (dimensionless)

- Temperature Correction Factor, in (Kg/m3);

viii

- Altitude correction factor, in (Kg/m3)

-Fan Power, in (kilowatts);

GkW - Gas (Air) kilowatt of Fan, in (kilowatts, kW);

K - Ratio of Specific Heats, Cp/ Cv , (dimensionless);

P1 - Fan Inlet Pressure, in [mm H2O (abs.)], or (in [Pa

(abs.)]);

Ps - Static Pressure of Fan, in [mm H2O (abs.)], or in [Pa

(abs.)];

Ps2 - Fan Outlet Static Pressure, in [mm H2O (abs.)], or in

[Pa (abs.)];

Pt - Total Pressure in (mm H2O), or in (Pa);

Ptf - Fan Total Pressure in (mm H2O), or (Pa);

PV - Velocity Pressure of Fan, in (mm H2O), or (Pa);

pv2 - Fan Outlet Velocity Pressure, in [mm H2O (abs.)],

or [Pa(abs.)];

r/min - Rotational Speed, in (rotations per minute);

T1 - Gas Temperature at Fan Inlet, in (K);

V1 - Fan inlet Rate, in (m/h);

V m - Gas Velocity, in (m/s);

VP -Peripheral Velocity, in (m/s);

t - Temperature Rise, in (K or degree °C);

ρ (rho)- Density (Mass Density), in (kg/m3 );

Subscripts:

t - Based on total pressure;

s - Based on static pressure;

1 - at inlet conditions;

2 - at outlet conditions.

V-BELT:

-Initial tension in the belt

-Tension in the slack side of belt

- Coefficient of increase of the belt length per unit force

b- Width of the belt a- Cross sectional area of pulley

ROTATING MASS: -Force acting outwards producing bending moment

ix

- Mass acting on the shaft – Rotating speed in rads/sec (Angular speed)

K – Spring stiffness

C – Damping coefficient e- Eccentricity t- Time

- Angular displacement

- Centripetal force of mass - Phase angle

BEVEL GEAR:

- Number of teeth on gear

- Number of teeth of pinion

- Diameter of gear

- Diameter of pinion

a- Breadth - Correct factor of safety

C – Deformation factor - Factor of safety

k- Wear strength

VERTICAL

SHAFT:

- Diameter of driving pulley - Diameter of driven pulley

- Shear stress

- Bending stress

- Speed of motor shaft - Speed of motor shaft

- Speed of horizontal shaft

P – Power in kilowatts N – Rotational speed of motor

T – Torque transmitted by the shaft - Actual power

- Angle of contact of belt

x

TABLE OF CONTENTS:

DECLARATION AND CERTIFICATION ............................................................................................... ii

DEDICATION ................................................................................................................................ iv

ACKNOWLEDGMENT..................................................................................................................... v

ABSTRACT ................................................................................................................................... vi

LIST OF FIGURES: .........................................................................................................................xii

CHAPTER 1: .................................................................................................................................. 1

1.0 INTRODUCTION:...................................................................................................................... 1

1.1 Definition of seeds, seed cleaners, purposes of seed cleaners and separators............................. 1

1.1.1 Seed cleaning ....................................................................................................................... 2

1.2 Background: ........................................................................................................................... 3

1.2.1 SUNFLOWER SEEDS: ............................................................................................................. 3

Description of the plant ................................................................................................................ 4

1.2.2 Climatic requirements .......................................................................................................... 4

1.2.3 Background on Sunflower; .................................................................................................... 6

1.2.4 STANDARD CLASSES OF SUNFLOWER SEEDS:........................................................................ 10

1.1.2 Threshing........................................................................................................................... 11

1.1.3 Cleaning............................................................................................................................. 12

1.1.4Storage ............................................................................................................................... 12

1.3.0 SEED CLEANERS AND SEPARATORS ...................................................................................... 13

1.3.1Types of seed cleaners available presently on the market;..................................................... 14

Product Description ............................................................................................................. 14

Basic Information ................................................................................................................ 15

Additional Information Trademark: JULITE ......................................................................... 15


Product Details .................................................................................................................... 16

Basic Information ................................................................................................................ 16

Dzl-10 Dustless Grain Seed Cleaner/Corn Cleaner ......................................................................... 18

Product Details .................................................................................................................... 18

Model NO.: DZL-10, Model: Dzl-10, Capacity: 10t/Hour, Motor Power: 1.5-4grade, Fan Power

and Rotate Speed:1.5kw/2900round/Minute .......................................................................... 18


CHAPTER 2: ................................................................................................................................ 21

2.1.0 COMPONENTS OF A SUNFLOWER SEED CLEANER: ................................................................ 21

xi

2.1.1 Pre- conditioning and pre cleaning ...................................................................................... 21

2.1.2 Cleaning:............................................................................................................................ 22

Air-Screen cleaner: ..................................................................................................................... 22

2.1.3 Screen Numbering System .................................................................................................. 23

2.1.4 Selecting screens: ............................................................................................................... 24

2.2.0 Cleaning and Grading:- ....................................................................................................... 30

2.2.1 Grader ............................................................................................................................... 30

2.2.2 Seed spiral separator .......................................................................................................... 33

CHAPTER 3: ................................................................................................................................ 35

3.1.0 Design of a sunflower seed cleaner ..................................................................................... 35

3.1.1 METHODOLOGY ................................................................................................................. 35

3.1.2 CONCEPT ........................................................................................................................... 36

3.1.3DESIGN OF PARTS................................................................................................................ 37

1.) VERTICAL SHAFT: ................................................................................................................... 37

3.) DESIGNING OF HELICAL SPRINGS; ........................................................................................... 65

4.) PROCESS DESIGN OF FANS AND BLOWERS............................................................................... 75

AXIAL FANS: ............................................................................................................................... 90

INTRODUCTION .......................................................................................................................... 90

4.) DESIGNING OF A V-BELT ......................................................................................................... 96

VIBRATIONS: ............................................................................................................................ 110

CHAPTER FOUR:........................................................................................................................ 115

4.1.0 DESIGN OF PARTS: ............................................................................................................ 115

4.1.1 FABRICATION OF MACHINE............................................................................................... 121

REFRENCES:.............................................................................................................................. 124

xii

LIST OF FIGURES:

Figure 1 Stationary thresher used to clean grain in the field ......................................................... 11

Figure 2: Seed Grain Beans Magnetic Separator (5CX-5) ................................................................ 14

Figure 3: 5xfz-25s Seeds Cleaner with Gravity Table ...................................................................... 15

Figure 4: Air Screen Grain Seed Cleaner with Cyclone Dust Separator ............................................ 16

Figure 5: cost = US $10000.0 ....................................................................................................... 17

Figure 6: 6-5XZC-3B Seed Cleaner and Grader Costs =US $ 3000.0-4000 ........................................ 19

Figure 7: Air-Screen cleaner......................................................................................................... 23

Figure 8: Example of screens for air cleaners ................................................................................ 29

Figure 9: Amos single spiral cleaner ............................................................................................. 33

Figure 10: High Mowing's Oliver 30 gravity table. ........................................................................ 34

Figure 11: Helical spring ............................................................................................................. 68

Figure 12: Stresses in the helical spring wire ................................................................................. 69

Figure 13: Stresses in helical spring with curvature effect.............................................................. 71

Figure 14: Deflection of helical spring .......................................................................................... 72

Figure 15: Comparison of efficiencies of five principal methods of controlling fan output ............... 84

Figure 16: Classification of ventilating and industrial fans.............................................................. 89

Figure 17: Airfoil as used in an axial flow fan blade [1] ................................................................. 90

Figure 18: NACA 6512 airfoil obtained from Mat lab.................................................................... 91

Figure 19: An asymmetric NACA 6512 airfoil as the cross section of a fan blade ............................ 92

Figure 20: NUMBER OF BLADES ................................................................................................... 93

Figure 21: V-belt and V-grooved pulley........................................................................................ 96

Figure 22: Balancing of rotating masses ..................................................................................... 103

Figure 23: Single rotating mass by a single mass rotating in the same plane ................................. 104

Figure 24: angular speed of rotation .......................................................................................... 110

Figure 25: plotting against r ...................................................................................... 112

Figure 26: Picture showing side view attachment of the rotating mass .......................................... 124

Figure 27: Original design of the components prime mover was derived from above machine ........ 124

Figure 28: Sketch of the final cleaning section of the seed-cleaner................................................ 124

xiii

OBJECTIVE OF THE PROJECT:

Our main purpose of doing this project was to find out the various methods used for

sunflower seed cleaning and main machines already in use to carry out this process, we also

had to investigate the major problems faced by farmers when in it comes to preparation of

sunflower seeds from the farm for processing and after all the above, we were to design and if

possible fabricate a simple sunflower seed cleaner that is both cost effective and efficient in

terms of usage or in case of breakdowns easy to repair, we were to base our idea from the

already existing machines.

METHODOLOGY:

To tackle the above objectives we first embarked on facts finding mission on the local

already operating plants for processing sunflower seeds to find out about their major

suppliers in terms of farmers or farms and if warranted we were to visit such places to inquire

more about what they normally do and possible problems they normally encountered among

the information they provided us with we came up with a project justification which is as

stated below

PROJECT JUSTIFICATION

The major problems encountered by farmers in our country today are lack of proper

technology to increase efficiency of harvesting and proper production quality of farm

produce.

We decided to find out more on main problems encountered by both small scale farmers and

large scale farmers specifically in sunflower seeds which are also cultivated within our

borders and it being among the most profitable seed industry of our generation in regards to

its usage. We discovered that the major problems encountered was labour cost incurred in

cleaning of the seeds as part of it is normally done manually, Cost of the machines to be used

is quite expensive hence not many can afford to purchase them hence this alone served as

major hindrance in farmers venturing into sunflower farming, we also found out that the

process in essence takes quite a lot of time to be completed and in most cases a lot of damage

is incurred to the seeds, we also found out that maintenance cost of the machines used in case

of those who have established such a plant, was quite staggering as the operation of the

machine itself required well trained personnel to operate and teaching it to workers is quite

another challenge that proved to be an expense, finally the repair of such machines in case of

breakdowns without skilled labor is quite a challenge hence the driving force behind our

design for a simpler efficient and a little bit cheap machine that is both easy to operate or

teach to operate and environmental friendly.

xiv

1

CHAPTER 1:

1.0 INTRODUCTION:

Agriculture is the largest single industry in the world, and seed production is an important

segment of this industry. Grass and legume seed production in the United States alone is

valued at more than $250 million annually, and imports represent another $15 million. When

the production of vegetable, grain, and flower seed is included, the total annual value climbs

to $750 million. Seed is important not only as planting stock but also as a source of basic raw

material for many manufacturing processes.

1.1 Definition of seeds, seed cleaners, purposes of seed cleaners and separators

Seed it has various definitions but one in particular stands out, it is an embryonic plant enclosed

in a protective outer covering called the seed coat, usually with some stored food . It is a characteristic

of spermatophytes (gymnosperm and angiosperm plants) and the product of the ripened ovule which

occurs after fertilization and some growth within the mother plant. The formation of the seed

completes the process of reproduction in seed plants (started with the development of flowers and

pollination), with the embryo developed from the zygote and the seed coat from the integuments of

the ovule. Seeds have been an important development in the reproduction and spread of gymnosperm

and angiosperm plants, relative to more primitive plants such as ferns, mosses and liverworts, which

do not have seeds and use other means to propagate themselves. This can be seen by the success of

seed plants (both gymnosperms and angiosperms) in dominating biological niches on land, from

forests to grasslands both in hot and cold climates. The term "seed" also has a general meaning that

antedates the above i.e. anything that can be sown, e.g. "seed" potatoes, "seeds" of corn or sunflower

"seeds”. In the case of sunflower and corn "seeds", what is sown is the seed enclosed in a shell or

husk, whereas the potato is a tuber. Many structures commonly referred to as "seeds" are actually dry

fruits. Plants producing berries are called baccate.

Sunflower seeds are sometimes sold commercially while still enclosed within the hard wall of the

fruit, which must be split open to reach the seed. Different groups of plants have other modifications,

the so-called stone fruits (such as the peach) have a hardened fruit layer (the endocarp) fused to and

surrounding the actual seed. Nuts are the one-seeded, hard-shelled fruit of some plants with an

indehiscent seed, such as an acorn or hazelnut.

2

Seeds are produced in several related groups of plants, and their manner of production distinguishes

the angiosperms ("enclosed seeds") from the gymnosperms ("naked seeds"). Angiosperm seeds are

produced in a hard or fleshy structure called a fruit that encloses the seeds, hence the name. (Some

fruits have layers of both hard and fleshy material). In gymnosperms, no special structure develops to

enclose the seeds, which begin their development "naked" on the bracts of cones. However, the seeds

do become covered by the cone scales as they develop in some species of conifer. Seed production in

natural plant populations vary widely from year-to-year in response to weather variables, insects and

diseases, and internal cycles within the plants themselves. Over a 20-year period, for example, forests

composed of loblolly pine and shortleaf pine produced from 0 to nearly 5 million sound pine seeds per

hectare. Over this period, there were six bumper, five poor, and nine good seed crops, when evaluated

in regard to producing adequate seedlings for natural forest reproduction.

Uses of seeds: Seeds can be used to

Add flavor to a dish.

Sunflower, sesame, and poppy seeds are very popular to eat. Nuts, like pecans and peanuts,

are seeds, too.

Seeds like corn and wheat make grain alcohol through a fermentation process.

Others are pressed for oil, such as flaxseed and grape seed.

You can decorate with seeds and seed pods by adding them to potpourri or flower

arrangements.

Seeds also make great additions to arts and crafts projects by adding color and texture.

Because they dry easily and store well, you can keep seeds on hand for use all year.

1.1.1 Seed cleaning is the act of removing chaff and other foreign particles from seeds that have

been harvested. Some seeds like tomatoes require special processes to clean them - e.g., fermentation.

It is important not only as planting stock but also as a source of basic raw material for many

manufacturing processes, Seed, as it comes from the held, contains various contaminants like

weed seeds, other crop seeds, and such inert material as stems, leaves, broken seed, and dirt.

These contaminants must be removed, and the clean seed properly handled and stored to

provide a high quality planting seed that will increase farm production and supply uniform

raw material for industry. The procedures used to meet present quality standards result in a

loss of up to 50 percent of the good seed even though many special machines and techniques

are used for seed cleaning and handling.

3

Attempts are being made to reduce seed losses by developing equipment and methods to

improve efficiency in cleaning, treating, handling, and storing of seed. Although the

research is concerned mainly with grass and small legume seeds, the techniques and

equipment involved are generally applicable to all types of seed—^forage, grain, vegetable,

flower, tree, and industrial oil seed.

Manufacturers of seed machinery have done an outstanding job in developing processing

equipment. Some of the present seed-cleaning machines make extraordinary separations of

small crop and weed seeds; however, the entire seed-cleaning problem is very complex, and

improvements are still needed in methods and equipment to reduce the heavy seed losses.

1.2 Background:

Seeds have adapted to their environment in different ways in order to survive and eventually

germinate. There are short- lived, recalcitrant seeds that must remain moist in order to survive.

Many short-lived seeds ripen in the spring and are often aquatic or nut species. Medium-lived

seeds, called orthodox, can remain viable for up to two to three years in the wild. In storage,

orthodox seeds such as conifers, fruit trees and grasses can remain viable for up to fifteen

years. Seeds with hard seed coats that are impermeable to water are long- lived. One of the

world’s longest-running experiments was initiated by Professor William James Beal in 1879

to investigate how long seeds can remain dormant and still germinate. After 126 years, seeds

are still viable. Once seed has been dried, it is ready for processing. Processing includes two

basic steps: threshing, which breaks the actual seed from its protective coating, and cleaning,

which “separates’ the wheat from the chaff,” so to speak.

1.2.1 SUNFLOWER SEEDS:

Sunflower is an important source of oil and proteins necessary for development of healthy

humans. By producing sunflower seeds, the main gains include the use of oil and proteins in

different forms. The content of the observed parameters varies and depends on numerous

factors. Environmental factors, the choice of genotypes and measures that apply during the

production of seed all the above mentioned influence the content of oil and proteins in

sunflower seed, as well as seed germination and also one of the most important seed

characteristics.

4

Description of the plant

Sunflower is an annual, erect, broadleaf plant with a strong taproot and prolific lateral spread

of surface roots. At the beginning of the season, the stems are round in shape and proceed to

be angular and woody later in the season. Sunflower leaves are phototropic and will follow

the sun’s rays with a lag of 120 behind the sun’s azimuth. This property has been shown to

increase light interception and, possibly, photosynthesis. In temperate regions, sunflower

requires approximately 11 days from planting to emergence, 33 days from emergence to head

visibility, 27 days from head visibility to first anther, 8 days from first to last another, and 30

days from last anther to maturity. Cultivar differences in maturity are usually associated with

changes in vegetative period before the head is visible. Its total growing period ranges from

125 to 130 days. The sunflower head is not a single flower (as the name implies) but is made

up of 1,000 to 2,000 individual flowers joined at a mutual receptacle. The flowers around the

circumference are ligulate ray flowers without stamens or pistils; the remaining flowers are

perfect flowers (with stamens and pistils). Anthesis (pollen shedding) begins at the perip hery

and proceeds to the centre of the head. As many sunflower varieties have a degree of self-

incompatibility, pollen movement among plants by insects is important, and bee colonies

have generally increased yields.

1.2.2 Climatic requirements

Temperature:

It is tolerant of both low and high temperatures, however, more tolerant to low temperatures.

The crop is particularly sensitive to high soil temperature during emergence. In South Africa,

this problem is aggravated in the sandy soils of the Western Free State and North West,

resulting in a poor or erratic plant stand. Sunflower seeds will germinate at 5°C; however,

temperatures of at least 14 to 21°C are required for satisfactory germination. Seeds are not

affected by the cold in the early germination stages. At later stages freezing temperatures

could damage the crop. Temperatures lower than the freezing levels are required before

maturing sunflower plants would die off. The optimum temperature for growth is 23 to 28 °C,

however, a wider range of temperatures up to 34 °C show little effect on productivity.

Extremely high temperatures have been shown to lower oil percentage, reduce seed fill and

germination.

5

Rainfall:

The rainfall requirement ranges from 500 to 1 000 mm. Sunflower is an inefficient user of

water, as measured by the volume of water transpired per gram of plant above-ground dry

matter. It is a crop which, compared to other crops, performs well under drought conditions;

this is probably the main reason for the crop’s popularity in the marginal areas of South

Africa. However, the crop is not considered highly drought tolerant, but often produces

satisfactory results while other crops are damaged during drought.

Its extensively branched taproot, penetrating to 2 m, enables the plant to survive times of

water stress. A critical time for water stress is the period 20 days before and 20 days after

flowering.

If stress is likely during this period, irrigation will increase yield, oil percentage and test

weight. Protein percentage, however, will decrease.

Soil requirement:

Sunflower will grow in a wide range of fertile soil types; sandy loam to clays with pH value

ranging from 6.0 to 7.5. Traditionally, sunflower cultivation has been limited to soils where

the clay percentage varies between 15 and 55 % (in other words, sandy loam to clay soil

types). At present the major planting areas are in soils with a clay percentage of less than 20.

Sunflower has a low salt tolerance; however, it is somewhat better than field bean or soya-

bean in this respect. Good soil drainage is required for sunflower production, but this crop

does not differ substantially from other field crops in flooding tolerance. Soils with good

water-holding capacity (clays) will be preferred under dry land conditions.

6

1.2.3 Background on Sunflower;

The scientific name for the sunflower is Helianthus. This name comes from the Greek for the

god of the sun Helios, and anthos, their word for flower.

The sunflower is native to North America. It is thought to originate in present day Mexico

and Peru. It grew wild all over the continent from the Paleo-Indian time. Today there are

approximately 67 species and subspecies growing wild across North America. Archaeologists

surmise that wild sunflowers were used as a food by Native Americans going back to 8,000

years ago. The seeds were high in fat, providing an easy energy source. The hulls were used

to make a drink and also for dyes and body paint. Dried stalks were used for building

materials and the oil was used for cooking, medicine and lotion. The use of the sunflower

image as a religious symbol has also been documented in some native societies. The Aztecs

in Southern Mexico wore crowns made of sunflowers in their temples.

The cultivation of sunflowers began in present-day Arizona and New Mexico about 3000

BC, before corn was grown as a crop. By about 2,300 BC, the Cherokee on the East Coast of

North America were also farming sunflowers. Through cross pollination and seed selection,

they encouraged plants with larger flowers and morseeds. The result was a stem with just

one large flower that held a large number of seeds in a variety of colors including black,

white, red, and black/white striped. In the 16th century, the European explorers were

introduced to the tall, brightly colored flowers. They learned how to grow them and sent

seeds back to Europe. The plants became widespread mainly as an ornamental, but some

medicinal uses were also developed. By 1716, an English patent was granted for squeezing

oil from sunflower seeds. In Russia, however, the manufacture of sunflower oil began on a

commercial scale in the 1830s. Sunflowers were farmed across that country on two million

acres. Government research programs were implemented and its oil contents and yields

increased significantly.

The Russian Orthodox Church increased the popularity of the sunflower by forbidding most

oil foods from being consumed during Lent. Since the sunflower was not on the prohibited

list, it gained an immediate popularity as a food.

Russian and German immigrants brought sunflowers with them when they move to the U.S.

and Canada in the 1900s. By 1880, seed companies were advertising the ‘Mammoth

Russian’ sunflower in catalogues.

7

In the 1930s, the Canadian government encouraged farmers to grow more sunflowers for

food. By 1946, Canadian farmers had built a small crushing plant and sunflower acreage

spread. In 1964, the Government of Canada licensed the Russian cultivar called ‘Peredovik.’

This seed produced high yields and high oil content. Sunflower continued to be hybridized in

the middle seventies providing additional yield and oil enhancement as well as disease

resistance. The first commercial use of the sunflower in the U.S. was as silage feed for

poultry. It wasn’t until the 1950s that the sunflower became an important agronomic crop in

the U.S., starting in North Dakota and Minnesota with commercial interest in the production

of sunflower oil.

By the 1970s sunflower farming spread into South Dakota and Kansas, then moving into

other states including Nebraska, Texas and California. Today Europe, Russia, Argentina,

China, India, Turkey and South Africa are also significant producers of sunflowers.

Sunflower production escalated in the late 1970s to over 5 million acres due to European

demand for sunflower oil. During this time, animal fats as a cooking oil were discouraged

due to cholesterol concerns. Russia could no longer supply the growing demand for the oil

and European companies began importing whole seed from the United States, which was

crushed in European mills. Today Western Europe depends on its own product ion and U.S.

exports to Europe of sunflower oil or seed for crushing is quite small.

8

Types of sunflowers grown commercially:

1. Oilseed: - This is a small black seed which is very high in oil content and is

processed into sunflower oil and meal. It is also the seed of choice of most bird

feeders. Of the two million acres of sunflowers that are grown each year, up to 90

percent are the oilseed type.

2. Non-oilseed:- This is also known as the confectionery sunflower. This is a larger

black and white striped seed used in a variety of food products from snacks to bread.

Uses of Sunflower seeds:

1. Food: -Sunflower seeds were roasted, cracked and eaten as a snack by Native

Americans. They were also fine ground into a meal that was used to thicken soups and

stews. Seeds were also ground or pounded into flour for cakes, mush or bread.

Roasted hulls were brewed to make a drink similar to coffee. Dye or paint could also

be extracted from the hulls and petal. Today sunflowers may be grown for their

flowers or for their seeds, which are used for both human and bird food. The

sunflowers that are grown for human consumption produce a large black and white

seed. The seeds are sold either shelled or unshelled.

A sunflower kernel is the “meat” of the sunflower seed. It has a mild nutty taste, but

tender texture. It is removed from the hull mechanically. The sunflower seed is an

inexpensive snack that is packed with healthy fats, protein, fiber, minerals, vitamins,

antioxidants and phytochemicals. One quarter cup (a one ounce serving) of sunflower

seeds contains 160 calories. The seeds are an excellent source of Vitamin E,

magnesium and selenium. One serving contains 90.5 % of the daily value of

Vitamin E, 31.9% of magnesium and 30.5% of selenium. They are also a very good

source of Vitamin B1, manganese, copper, phosphorus, Vitamin B5 and folate .

Researchers at Virginia Polytechnic Institute found that sunflower kernels and

pistachios had the highest levels of phytosterols among commonly eaten seed and

nut snacks. This class of plant chemicals has been shown to reduce cholesterol levels

and improve heart health. Sunflower seeds are not a commonly allergenic food and

are not known to contain measurable amounts of oxalates or purines. Since sunflower

seeds are high in fat, they are prone to rancidity. Store in the refrigerator in an airtight

container, or store in the freezer. The cold temperature will not significantly affect the

texture or flavour.

9

2. Oil: -Sunflower oil is produced from oil type sunflower seeds. These small black

seeds are high in oil content. This is also the type of sunflower seed that is the choice

for bird food and that is ground into sunflower meal for use in animal feeds. Today

sunflower oil is marketed worldwide and is second only to the soybean as an oil-seed

crop. Sunflower oil is preferred healthy cooking oil. It is light in color and has a light

neutral taste even when used for frying. It is a combination of monounsaturated and

polysaturated fats with low saturated fat levels. It is ideal for cooking because it can

withstand high temperatures. It also supplies more Vitamin E than any other

vegetable oil.

There are three types of sunflower oil available on the market today. All are

developed with standard breeding and hybridizing techniques. They differ in oleic

levels and each offers a unique culinary purpose. The three types are linoleic, high

oleic and NuSun sunflower oil. High oleic sunflower provides above 82 percent

oleic (monounsaturated) acid. NuSun is a mid-range oleic sunflower oil. It needs no

hydrogenation when cooking and has a 9 percent saturated fat level, making it

extremely useful for frying. It also has a good balance of linoleic acid, an essential

fatty acid that enhances its taste. Sunflower oil is also used as biodiesel. This

vegetable-oil based fuel is used for vehicles, including farm equipment. It burns 75

percent cleaner than petroleum based diesel and is a good lubricant, reducing wear on

engine parts.

3. This useful flower also has been used for centuries as medicines and in paints. Today

they are added to some varnishes and paints due to their quick-drying quality.

4. Sunflower oil is also being added to detergents and soaps.

5. It is also being tested for use in plastics, lubricants and even pesticides.

6. Sunflowers are also being used as a bio fuel.

7. One beneficial uses of sunflowers is in the removal of toxic waste from the

environment. Using an emerging technology called rhizofiltration; hydroponically

grown plants are grown floating over water. The extensive root systems of the

sunflowers can extract large amounts of toxic metals, including uranium, from the

water.

10

1.2.4 STANDARD CLASSES OF SUNFLOWER SEEDS:

• A consignment of sunflower seed shall be classified as:

1. Class FH if it:

consists mainly of sunflower seeds with a high oil content

does not contain more than 20 % sunflower seed of Class FS or Class FGP

complies with the standards for Grade 1 set out in regulation 6

2. Class FS:

consists mainly of white sunflower seeds or clearly white-striped sunflower seeds or a

mixture of white and white-striped sunflower seeds registered and described as a

variety suitable for bird feed, in terms of the Plant Improvement Act, 1976 (Act No.

53 of 1976)

does not contain more than 20 % sunflower seed of Class FH or Class FGP

complies with the standards for Grade 1 set out in regulation 6

3. Class FGP:

consists of large sunflower seeds of which not more than 5 % passes through a 5,5

mm round hole screen

complies with the standards for Grade 1 as set out in regulation 6

4. Class Other Sunflower Seed:

does not comply with the requirements for Class FH, Class FS or Class FGP

11

Grades for Sun-Flower seeds:

There is only one grade for the Classes FH, FS and FGP Sunflower Seeds.

A consignment of Grade I sunflower seed should:

• Be free of a musty, sour, khaki-weed or other undesirable smell

• Be free of any substance that renders it unsuitable for human or animal consumption or for

processing into or utilization as food or feed

• Contain no more than 5 noxious seeds per 400 g, of which no more than one may be of

Crotalaria species and of which none may be of Ricinus communis

• Be free of stones, glass, metal, coal or dung

• Be free of insects

• Not exceed the maximum permissible deviation

• Contain no more than 10 % moisture

1.1.2 Threshing

There are many techniques for threshing; it takes only a little imagination. One of the

simplest ways is to rub the harvested material against a coarse screen with a gloved hand. Try

rubbing the plant between two ping-pong paddles. Or, alternatively, you could cut open an

inner tube, tie off one end, place the material to be threshed inside, and then roll the tube

underfoot on the floor. For removal of seeds from pods, a rolling pin and a wooden tray may

be effective. Or gently rub the pods between two bricks. Mechanical threshing may be

accompanied by employing a hammer mill. This method works particularly well on the

hulled seeds of tick trefoil, bush clover, bee balm and black-eyed Susan.

Figure 1 Stationary thresher used to clean grain in the field

12

1.1.3 Cleaning

The aim is to get seed completely clean. While this ideal is not 100% attainable, don’t worry;

the seed will grow. Still, strive for the 100% clean because it will reduce the volume of

material to be stored, it will make sowing of the seed easier, and it will inc rease the

likelihood of planting viable seed. Cleaning is accomplished by shaking the threshed material

through progressively tighter meshed screens. Naturally, not all undesirable material will be

sifted out, but there are various methods for removal of the dirt and smaller pieces of plant

material that remain. Since the desirable seed is denser than the leftover material it is a simple

process to blow that material away. With this process, a little experimentation is in order.

Place a fan (or perhaps a hair dryer) on a table, and winnow the chaff from the seed. The trick

is to discover at what distance to place the wind source so the chaff but not the seed itself will

blow away. Start at a greater distance and move closer as the seed gets cleaner—an ounce of

caution is worth a pound of cure! Commercial seed producers use a fanning mill in the final

stages of seed cleaning. Note: This process may be dusty so participants may want dust

masks.

1.1.4Storage

Storing seeds in the right conditions can be very important for maintaining their viability. For

medium- and long- lived seeds, removing the chaff and other plant parts can assist in drying

the seeds and increase the success of storage. Dry seeds still need 3-8% moisture to remain

viable. Store in sealed containers, such as ice cream pails or yogurt containers, in a

refrigerator set at 41 degrees Fahrenheit.

13

1.3.0 SEED CLEANERS AND SEPARATORS

Seed cleaning should be done in the field before the crop is harvested. Good cultural practices

like spray programs, crop rotation, and rouging can minimize many serious weed and

contaminant problems. When a seed lot enters the processing plant for cleaning, contaminants

are removed by the use of special equipment that takes advantage of differences in physical

characteristics of various components in the mixture. The chief characteristics used in making

separations are size, shape, density, surface texture, terminal velocity, electrical conductivity,

color, and resilience. Many types of seed-cleaning machines are available that exploit the

above physical properties of seed, either singly or in some combination.

There are air-screen cleaners, specific gravity separators, pneumatic separators, velvet roils,

spirals, indent cylinders, indent disks, magnetic separators, e lectrostatic separators, vibrator

separators, and others. Of these, the most widely used machine is the air-screen unit; it is

common to all seed-cleaning plants from the small farm operation to the largest commercial

installation. All the other separators can be considered secondary machines which follow the

air-screen unit in the processing sequence. The choice of machines used and their

arrangement in a processing line depends primarily on the seed being cleaned, the quantity of

weed seeds and other contaminants in the mixture, and the purity requirements that must be

met. Seed for planting is of little value unless it reaches the farmer in a viable condition,

essentially free of contaminants, and at a price he can afford. The degree to which these

requirements are satisfied is related to the equipment used, its arrangement in the processing

plant, and the knowledge and skill of the man operating the machine.

14

1.3.1Types of seed cleaners available presently on the market;

Figure 2: Seed Grain Beans Magnetic Separator (5CX-5)

Cost= $1000.0 - $10000.0

Product Description

1.5CX-5 high-performance Magnetic Separators

2.it is to separate clod from grain.

3. It is based mainly on grain mixed with mud and clod, with the appropriate

speed through a closed strong magnetic field.

4. When the material spilled out, due to the different strength of attraction of the

magnetic field, and shed the near and far, to separate clod from grain.

Advantages:

1. 304 stainless steel sheet metal machine, magnetic closure strict, less magnetic

flux leakage.

2. The magnetic field strength of magnetic roller is greater than 14, 000 gauss.

3. The wide magnetic surface design, width of magnetic election surface is

1300m, to ensure that the processing capacity and improve the magnetic effect.

4. The original design of bulk grain equipment, bulk grain uniform, no

maintenance, greatly reducing the losses caused by the vibration feeder damage.

Mode

l

width for magnetic

election

mm

magnetic

intensity

GS

Capacit

y

Kg/h

Power

Kw

clod

election

Overall Size

H x W x Hmm

5CX-

5 1300

> 14000 5000 0.75 > 98.9%

1800x1800x200

0

15

Figure 3: 5xfz-25s Seeds Cleaner with Gravity Table

Cost =$1000.0 - $13000.0

Basic Information

Model NO.:5XFZ-25S Elevator: Built in, Winnowing: Air Screen, Wind Pressure: Can Be

Adjusted

Seed: Wheat Corn Sorghum Filed Crops, Sieves: 1250X1200mm, Gravity Table:

1700X1600mm, Grain Exit: Two

Additional Information Trademark: JULITE

Standard: ISO9001: 2008, Production Capacity: 2000sets/Year

Product Description

This machine consists of ultra low speed, no broken elevator, vertical air screen, cyclone dust

er system, front semi-sieve, large proportion platform.

It can remove dust, chaff, shell and other light impurities, It also can remove the blighted see

d, budding seed, damaged seed (by insect), rotten seed, deteriorated seed, moldy seed,

Nonviable seed, seed with black powder sick. When the large and small impurity have remov

ed, the finished product separate to best, medium and small particles.

16

Name Model Sieve Size(

mm)

Powe

r

(kW)

Capaci

ty(t/h)

Weight

(kg)

Overall size

L×W×H(mm

)

Remarks

Gravity Tab

le

Front

semi-

sieve

seed

Commo

dity grai

n

Air-

screen Cleane

r with Gravity

Table

5XFZ-

25S 1700×1600

1250×

1200 12.5 10 20 1600

3110×2100×

3600

With fro

nt semi-

sieve

Figure 4: Air Screen Grain Seed Cleaner with Cyclone Dust Separator

Cost = US $10000.0

Product Details

Basic Information

Model NO.:5XZC-5DH,Grain Seed Cleaner Separator, Machine Color: Green,

Power:0.75kw, 1.5kw, Transmit: Belt Transmit/ Drive, Buckets Type: PVC Bucket.,

Production Capacity:5 Ton/Hour

17

Product Description:

Features of 5XZC-5DH seed cleaner:

The 5XZC-5DH seed cleaning machine equipped with Cyclone dust separator is

professionally used for cleaning and grading seeds / grains.

Application of 5XZC-5DH seed cleaner:

The 5XZC-5DH seed cleaning machine is widely used for cleaning and grading agricultural

products, such as grain seed, tree seed, grass seed, oilseed, commodity grain, etc.

Working principle of 5XZC-5DH seed cleaner:

Light impurities can be sucked out by air cleaning system. After the left materials enter into

vibratory sieving trunk, the large and small impurities will be removed and at the same time

the seed will be separated into different levels.

The grading and cleaning functions of vibratory sieve based on the geometrical size

characteristic of seed, and change the sieves you can processing all kinds of seeds.

.

Figure 5: cost = US $10000.0

Model No. Capacity(

T/H)

Power(K

W)

Weight(

KG)

Sieve

Size

Dimensions(

MM) Remarks

5XZC-5DH grain cleaner

5 7.74 1.6 2000×1000

4970×1900×3100

With cyclone dust separator

5XZC-7.5D grain

cleaner 7.5 10.1 1.7

2400×12

50

5150×2160×

3500

5XZC-15 grain cleaner

10 10.5 1.8 2400×1500

5400×2350×3500

18

Dzl-10 Dustless Grain Seed Cleaner/Corn Cleaner

Product Details

Model NO.: DZL-10, Model: Dzl-10, Capacity: 10t/Hour, Motor Power: 1.5-4grade,

Fan Power and Rotate Speed:1.5kw/2900round/Minute

Dimension (Mm):3100*1450*2750, Production Capacity:100sets/Month

Product Description

Description:

Portable grain cleaner is suitable for selection of corn, soybean, wheat, rice sunflower seed et

c. The screen deck could be changed according to the grain particle size.

Handling capacity: 10T/H (wheat)

Screen decks: 2

Total power: 3kw (2 motors)

Features:

Dustless during the cleaning, significantly change the selection environment, applies to

indoor cleaning work as well. This machine is equipped with a centrifugal fan, Dust collector,

Shelter unloading box, Mobile conveniently; Selection precision can reach above 90%.

19

Figure 6: 6-5XZC-3B Seed Cleaner and Grader Costs =US $ 3000.0-4000

5XZC-3B Seed Cleaner and Grader universal type can process most kind of seeds, with a

dust collector, usually with 2 screen layers, and can grade the seeds in three levels by

size. This machine is used for primary seed/grain cleaning to remove the light impurity,

large size impurity and small size impurity. Synmec's seed cleaner and grader is used

primarily for grain cleaning in flour mills and grain storage facilities (silos). It removes

coarse and fine impurities from the grain by sieving. It also grades various products

according to size. Main application areas of the cleaner are mills processing soft wheat,

durum, corn (maize), rye, soybeans, oats, buckwheat, spelt, millet and rice. It is also used

successfully in feed mills, seed cleaning plants, oilseed cleaning installations and for

cocoa bean grading.

20

Model 5XZC-3B

Dimension(L*W*H) 3970*1800*2750 mm

Capacity 3000kg/h (count by Wheat)

Power 4.25 KW in total.

Air blower 3 KW

Motor for elevator 0.75 KW

2 * vibratory motors 0.25 KW * 2

Weight 1.2T

Sieve layer 2 -3 layers available by customer's

requirement

Screen size(L*W) 1250*800mm

Working theory and work flow

Wind separating function depends on the vertical air-recycling unit, it uses aerodynamic

properties of grains and the critical speed difference between grains and impurities adjust

air flow speed to achieve the separation.

The light impurities are aspirated and collected by the cyclone dust collector, better grains

stay and enter main sieving chamber after the wind separation. Normal vibratory sieve

chamber consist of two sieve layers (or more) with three discharging outlets (or more)

which discharge large impurities small impurities and good (selected) grains.

Due to the size difference of various grains, appropriate sieve mesh selection is crucial to

achieve the grading and selecting function within the vibratory sieve chamber. After

processed by Synmec Grain Cleaner and Grader, the grains quality are improved and

increased grains selling price, this make it becomes one of the most favorite grain

cleaners in the global market.

21

CHAPTER 2:

2.1.0 COMPONENTS OF A SUNFLOWER SEED CLEANER:

Seed cleaner process involves removal of materials like dirt, dust, leafs, stones etc. A good

example of a seed cleaning machine is one manufactured by MITSUN which is used in two

layers where all these materials are being removed. Seed Cleaners are used to remove the

waste materials like dirt particles, small stones and leaves. Above mentioned seed cleaner

machinery contains chambers of pre-cleaners, length separators and gravity separators

depending on the need of the customers.

Seed cleaning and sorting is done by grain cleaning machines, whose operation is based on

differences in dimensions (thickness, width, and length), weight, aerodynamic qualities

shape, and surface texture of the seeds.

Pneumatic sorting tables are used to separate seeds by weight, and a grain cleaning column is

used for cleaning seeds from other substances with different aerodynamic properties. Gravity

seed cleaners and electromagnetic seed cleaning machines sort the seeds by shape and surface

texture.

The cleaned seeds of corn, cotton, sugar beets, and sunflower are d ivided according to size

into groups. This ensures even sowing, sprouting, and development of the plants.

There are various seed processing techniques but among the principle one are as follows;

2.1.1 Pre- conditioning and pre cleaning - the earlier refers to Isolation of seed from plant

parts with which it was harvested e.g. Shelling and the later refers to removal of external

materials like trash, stones, clods which are either in larger size or lighter in weight. No pre-

cleaning is required for hand harvested and winnowed seeds. The machineries involved in

this operation are, Scalper which removes the larger inert matter from the seeds. If it contains

a single sieve it is referred to as scalpers and if it has two sieves it’s called rough cleaners.

The unit consists of a vibrating or rotating screen or sieve having perforation large enough to

allow the rough seed pass through readily. Seed Scalper (Debearders) the machine has

horizontal beater with arms rotating inside a steel drum. When the seeds pass thro ugh it, the

action of rubbing the seeds and clip the seeds of oats is performed on debeard barley, thresh

white cap in wheat, remove awns and beards, de hull some grass seeds and polish the seed.

Debearders (Huller -scarifier) have two rubber faced rough surfaces to rub the seeds.

22

Dehulling (removal of outer coat or husk) and scarifier (scratching the seed coat) can be done

simultaneously or separately. Its operations, Seed is passed to a rotating disc that is under

centrifugal force which is then thrown to a huller, the suction chamber- removes lighter seeds

i.e. Maize Sheller 1. High capacity power operated shellers – bulk 2. Hand shellers breeder

or nucleus seed.

2.1.2 Cleaning: - The second stage of cleaning is carried out with air blasts and vibrating

screens and is applicable to all kinds of seeds. It is essentially the same as scalping but more

refined. It is performed mostly by one machine known as air-screen cleaner. Air-Screen

cleaner cum grader, the air-screen machine is the basic cleaner in most seed processing

plants. Almost all seed must be cleaned by air-screen cleaner before specific specifications

can be attempted. Machine size varies from small, two-screen farm models to large industrial

cleaners with 7-8 screens. Two-screen models are used on farms, in breeder and foundation

seed programs and by experiment stations for processing small quantities of seed. In most

machines separations are made on the basis of differences in only one physical characteristic.

The air-screen machine, however, affects separation on the basis of differences in size and

weight of seeds. This enables the air-screen machine to use three cleaning elements:

aspirator, where light material is removed from the seed mass; scalper where seeds are

dropped through screen openings; but larger material is carried over the screen into a separate

spout; and grader, in which good crop seeds ride over screen openings, while smaller

particles drop through.

Air-Screen cleaner:

The air-screen cleaner is the basic machine in a seed-cleaning plant. It makes seed

separations mainly on the basis of three physical properties; size, shape, and density. There

are many makes, sizes, and models of air-screen cleaner’s ranging from the small, one-fan,

single-screen machine to the large, multiple- fan, six- or eight-screen machine with several air

columns. Screens are manufactured with many sizes and shapes of openings. There are more

than 200 screen types available, and with a four-screen machine, more than 30 thousand

screen combinations are possible.

The typical air-screen cleaner now found in a farm seed-cleaning plant is a four-screen

machine located beneath a seed hopper, as shown in the figure below.

23

Figure 7: Air-Screen cleaner

Seed flows by gravity from the hopper into a feeder that meters the seed mixture into an

airstream, which removes light, chaffy material so that the remaining seed can be distributed

uniformly over the top screen. The top screen scalps or removes large material, the second

screen grades or sizes the seed, the third screen scalps the seed more closely, and the fourth

screen performs a final grading. The finely graded seed is then passed through an air-stream,

which drops the plump, heavy seed, but lifts and blows light seed and chaff into the trash bin.

The arrangement described above uses two screens as top screens and two as bottom screens.

Other arrangements possible with a four-screen machine are three top and one bottom, or one

top and three bottom.

2.1.3 Screen Numbering System

The size of a round-hole screen is indicated by the diameter of its perforations. Perforations

larger than 5i/2/64ths of an inch are measured in 64ths. Therefore, a 1- inch round hole screen

is called a No. 64 and a 1/2- inch screen is a No. 32, and so forth.

Screens smaller than 5i/2/64ths of an inch are measured in fractions of "an inch. Therefore,

the next size smaller than 51/) is l/12th; then, in descending order, l/13th, l/14th, and so forth.

The smallest round-hole perforation commonly used in air-screen machines is a l/25th which

has a hole diameter of 0.040 inch. However, for special cleaning requirements, round hole

screen in smaller sizes (down to 0.016inch) can be obtained from manufacturers of perforated

metal. These special screens use a different numbering system and must be mounted on

frames to fit air-screen machines.

Swedish and other foreign manufacturers use the metric system in designating sizes of screen

openings. Oblong-hole screens are measured in the same manner as round-hole screens

except that two dimensions must be given. In slotted screens, the hole width is indicated in

24

64ths of an inch; for example, 11 X % means an opening ll/64ths of an inch wide and %ths o f

an inch l one. In slotted screens smaller than 5V2/M x %, width is generally indicated in

fractions of an inch; for example, 1/12 x 1/2- There are some exceptions to this latter

desiornation in that such sizes as 5/64 x %, 47/8/64 x %, 3/64 x 5/16, and others, use the

large-screen numbering system with hole widths indicated in 64ths of an inch. In all cases,

the final number is the length of slot.

Wire-mesh screens are designated according to the number of openings per inch in each

direction. A 10 x 10 screen has ten openings per inch across, and ten openings per inch down

the screen. The size 6 x 22 has twenty two openings per inch across the screen, and six

openings per inch down the screen. Such screens as 6 x 22 have openings which are

rectangular in shape, and are the wire-mesh equivalents of oblong-perforated or slotted

screens.

Triangular screens may be measured in two ways. The system most commonly used in the

seed industry indicates length of each side of the triangle in 64ths of an inch. The sides of the

hole in a No. 11 triangular screen are ll/64ths of an inch long. Another system used by

perforators is to designate the triangular opening as the diameter of the largest circle that can

be inscribed in the triangle.

2.1.4 Selecting screens:

The two basic screens for cleaning round shaped seed are a round-hole top screen and a

slotted bottom screen. The round-hole top screen should be selected so as to drop the round

seed through the smallest hole possible, and retain anything larger. The seed drops through

the top screen onto the slotted bottom screen, which takes advantage of seed shape and

retains the round, good seed while dropping broken crop seed and many weed seed. The

basic screens for cleaning elongated seed (oats, fescues) are a slotted top screen and a slotted

bottom screen. In special separations it may be necessary to pass such seed through round-

hole top screens or over some screen other than a slotted bottom screen, but generally, slotted

top and bottom screens are used.

The basic screens for lens-shaped seed (lentils, flax, and Korean lespedeza) are usually a

slotted top screen and a round-hole bottom screen. These shapes allow the best cleaning

possible when a machine is equipped with only one top and one bottom screen. The lens

shaped seeds tend to turn on edge and drop through a slotted top screen but lie flat and travel

over a round-hole bottom screen, which will pass most other crop and weed seeds.

25

Since most air-screen cleaners have more than two screens, the genera l rule is to equip the

cleaner with oblong- and round-hole top screens, and oblong, and round, square or triangular-

hole bottom screens. With few exceptions, this system assures the most thorough seed

separation.

One of the lens-shaped seeds commonly cleaned with an oblong-perforated top screen and a

round-hole bottom screen is flax. This slick, shiny seed must turn on edge to drop through the

oblong holes. If the top screen is a perforated-metal type, some of the seeds will slide over

the screen without turning on edge, thus reducing capacities and increasing seed loss. When a

wire-mesh screen with rectangular openings is used in place of the oblong-perforated screen,

greater capacities and accuracy can be achieved for two reasons: The roughness of the wire

surface encourages the flax to turn on edge more readily and drop through the openings, and

the wire mesh presents many more openings per square inch of screen area.

Many seed shapes cannot be neatly classified as round, elongated, or lens like. For example,

timothy is shaped like a football, vetch-ling like a cube, and dock or sorrel like a pyramid.

Corn occurs in many irregular shapes, and sudan-grass falls in an intermediate classification

between round and elongated. Consequently, when screen types are selected for specific

seeds, the choice depends largely upon what must be removed from that mixture. When

sudan-grass is cleaned in a multiple screen unit, the top screens usually will be a round-hole

and an oblong, and the bottom screens also have a round-hole and an oblong. Since seed

shape and size are so important in screening operations, seed measuring has been investigated

as a basis for selecting optimum shape and size of screen holes.

Factors to consider when selecting types of screens to use;

Percentage of Open Area: - A good screen must have openings as close together

as possible without impairing the structural strength of the material. Wire-mesh

screens have more openings per square inch than perforated-metal screens. For

this reason, they are excellent bottom screens for small seeds, and they permit a

more accurate high- capacity screening than is possible with perforated-metal

screens. Comparing a perforated-metal screen to an equivalent wire-mesh screen,

the perforated screen has only a fraction of the total number of openings per

square inch that are available in the wire-mesh screen, and consequently would

reduce capacity if used. They exist in a given standard as indicated below in

inches:6x14, 6x15, 6x16, 6x18, 6x19, 6x20, 6x21, 6x22 , 6x23, 6x24, 6x25, 6x26,

6x28, 6x30, 6x32, 6x34, 6x36, 6x38 , 6x40, 6x42, 6x50, 6x60 .Another reason

26

that wire-mesh screens serve better as bottom screens is that their surfaces are

rough and seeds passing over them are caused to turn, tumble, and present all

sides to the openings. As a result, if the seeds are small enough in one dimension,

they have every chance to drop through. Perforated-metal screens have smooth

surfaces and seeds may lie flat and "float" over the openings. Bottom screens may

take advantage of this flotation. In this case, it is desirable for the good seed to lie

flat and float over the perforations rather than turn on edge and drop through the

screen along with the contaminants.

Length of Slot: - Slotted screens are perforated in different lengths, such as the

sizes 1/14 x 14 and 1/14 X 1/1; Seed processors use the half- inch length to drop

hulled oats when they are cleaning seed oats. Cleaners of market grain want to

hold the hulled oats but drop small weed seed. In this case, the shorter slotted hole

is desirable because it will float the long seed (oats) over the screen but drop the

weed seeds. Processors of Korean and Kobe lespedeza find that the 1/18 x 14 slot

is fine for Korean but a longer slot, size 1/18 x V2 or 1/18 x %, is needed for

Kobe, which is a flatter, wider seed, and will not pass rapidly enough through the

1/18 X l slot. For the same reason, three-quarter- inch long slots is good in a

bottom screen for cleaning seed wheat because it effectively drops wild oats,

quack grass, or cheat without losing any more good wheat than would be dropped

with a shorter slot. The length of slot should be carefully considered when

selecting a slotted screen. For a top screen, the slot must be long enough to pass

good seed freely and give adequate capacity. In a bottom screen, the slot should be

long enough to give weed seed every chance to engage the perforation and drop

through, yet short enough to prevent excessive loss of crop seed.

Screen Dams: - Refers to objects fastened to a screen to make it sift more

completely than normal. They are used for very close and accurate separations of

small round seed. For example, dodder can be removed from Korean lespedeza

with a one sixteenth round-hole bottom screen equipped with dams. Operators of

flat-screen corn graders frequently use dams on all screens to insure maximum

accuracy of grade. Dams may be constructed of any material, but commonly are

strips of wood lath about a quarter of an inch high and 2 inches wide. When

fastened over the cross braces of the screen with nails or screws, the dams are

positioned cross-wise to interrupt the smooth flow of seeds down the screen,

27

causing them to stop momentarily and be thoroughly sifted. This provides ample

opportunity for all seeds to contact the perforations and to drop through the screen

if size and shape of the openings permit. Dams also can be used to cause

elongated seeds to upend and drop vertically through a round or slotted hole. For

example, screen dams are effective in separating ryegrass and flaxseed. When this

mixture is passed over one-twelfth round-hole screen with dams, the seed flow

across the screen is retarded and gets collected behind the dams. As the ryegrass

attempts to work its way over the dam, it approaches an upright position and the

oscillation of the screen causes the seed to pass through the screen endwise,

making the separation. Also, rattail fescue can be dropped from fine fescue using

a 6 x 26 slotted wire screen fitted with dams. When screen dams are used on

round-hole-bottom screens, the accuracy of sifting is increased so that a heavier

layer of seed may be carried on the screen, with a resultant increase in capacity.

Except when a screen is being used for grading, dams are generally used only on

bottom screens. Ordinarily, top screens drop their good seed quickly enough, and

dams on a top screen would cause some weed seeds that normally flow over the

screen to stand on end and drop through with good seed. Because of the close

sizing and upending of seeds that dams encourage, there is a tendency for screen

holes to plug more readily than in conventional screening. This means that more

attention must be paid to keeping the screens clean.

Screen Attachments: - Most air-screen cleaners are equipped with travelling

brushes beneath the screens that move from side to side sweeping lodged seed

from the openings. The two materials used for brush bristles are hair and nylon.

Nylon, although more expensive initially, will last considerably longer and do a

more effective job of dislodging seed than the hair bristles. Rollers or flat wipers

also may be used under screens instead of brushes. Mechanical hammers or

bumpers are sometimes used to assist brushes in dislodging seed by striking the

screen ribs periodically at top centre, bouncing seed free of the openings. An

attachment that can be used to improve the separating action of a top screen is a

piece of oilcloth lying flat on the screen with the slick side down. The seed

mixture flows between the cloth and screen, and the weight of the cloth tends to

keep long pieces of straw and stems flat on the screen so that they do not stand on

end and pass through the openings with good seed. In some cases, it is a good

practice to blank off the lower section of a top screen. Once a line has been

28

determined where all the good seeds have dropped through, the screen can be

blanked off from that line to its discharge edge with paper, plastic, sheet metal, or

other suitable material. Then, any undesirable material that has passed over the

upper section of open perforations will flow onto the blanked-off portion and have

no further chance to stand on end and drop through with good product.

Adjustments: - Feed rate can be adjusted by increasing and decreasing the speed

of the metering roller or by varying the opening of the metering gate located in the

bottom of the feed hopper. The feed rate should be regulated to keep the final

grading screen about seven-eighths full. It is better to have a small section of the

screen uncovered part of the time than to flood the screen occasionally. Airflow is

usually regulated by means of baffles in the air ducts. The top air is adjusted to

blow out light chaffy material and dust. The bottom air is regulated to a higher

blast than the top air so that it will blow out light seed and heavier trash.

Oscillation of the screens is controlled by means of variable-speed pulleys and

should be adjusted to keep the seed action 'alive'' over the screen. The greater the

oscillation, the faster the seed movement over the screens. If this movement is too

fast, the seeds hop across the screen and will not be separated. If it is too slow, the

seeds have a tendency to glide across the screen with the larger material and not

sift through. The pitch can be adjusted for each screen individually in most air-

screen machines. The steeper the screen, the faster will be the flow of seed across

it, and the more likely a long seed is to stand on end and go through. The smaller

the pitch angle, the longer the material takes to pass over the screen. This gives

more time and a better chance for seed to line up with a hole and pass through the

screen, as well as the best chance for a long seed to stay in the horizontal position

and slide over the screen instead of through it.

Capacities: - Capacities for air-screen machines vary considerably depending on

the machine size, the crop seed being processed, and the amount and type of

contaminant to be removed. Approximate rates listed by manufacturers for a four-

screen machine (screen size: 42 inches wide and 44 inches long) are 75-125

bu./hr. For seeds, 100-175 bu. /hr. for cereal grains, and 200-350 bu./hr. for beans.

29

Further Cleaning;

After seed is cleaned on the air-screen machine, it is inspected to determine if further

separating is needed, and, if so, what special machines are required to make the specific

separations. Subsequent cleaning may be done with additional units that again use size

properties. Or, machines may be employed that exploit other physical properties of seed like

density, surface texture, or terminal velocity. The characteristic differences in the physical

makeup of the seed and its remaining contaminants will dictate the equipment to be used

next.

Example of screens for air cleaners:

Figure 8: Example of screens for air cleaners

30

2.2.0 Cleaning and Grading:-

2.2.1 Grader

The grader is a size separator that classifies seed either by width or thickness. It employs

cylindrical screens or 'shells" that are mounted horizontally and have slotted or round

perforations, the seed lot to be separated is fed into one end of the rotating shell where it

tumbles and migrates toward the tail end. Longitudinal movement is caused by a continuous

spiral channel and a slight incline of the cylinder. During the transit, seeds or particles

smaller than the perforation drop through the shell while larger material is retained and

discharged out the tail end. The dropped material may be directed to a vibrating conveyor,

screw auger, chute, or other means of removing it from the machine.

To obtain quality seed, it is necessary to clean the seed obtained from the farm to get rid of

inert materials, weed seeds, other crop seeds, other variety seeds, damaged and deteriorated

seed. Different kinds of seeds can be separated when they differ in one or more physical

characteristics. Physical characteristics normally used to separate seeds are size, shape,

length, weight, colour, surface texture, affinity to liquids, electrical conductivity, etc. The

problem lies in identifying the most important property and use the machine that separates

seed using the identified property. Some of the identified properties and machines operating

by following the properties are listed below:

1. Specific gravity separation- This method makes use of a combination of weight and

surface characteristics of the seed to be separated. The principle of floatation is

employed here. A mixture of seeds is fed onto the lower end of a sloping perforated

table. Air is forced up through the porous deck surface and the bed of seeds by a fan,

which stratifies the seeds in layers according to density with the lightest seeds and

particles of inert matter at the top and the heaviest at the bottom. An oscillating

movement of the table causes the seeds to move at different rates across the deck. The

lightest seeds float down under gravity and are discharged at the lower end, while the

heaviest ones are kicked up the slope by contact with the oscillating deck and are

discharged at the upper end. This machine separates seeds of the same density but of

different size and seeds of the same size but of different densities.

31

2. . Air-screen cleaner 12_gravitytable Specific gravity separator Indented

cylinder;- This helps to separate seeds according to the length. The equipment

consists of a slightly inclined horizontal rotating cylinder and a movable separating

trough. The inside surface has small closely spaced hemispherical indentations. Small

seeds are pressed into the indents by centrifugal force and can be removed. The larger

seeds flows in the centre of the cylinder and is discharged by gravity

Gravity tables employ vibration and forced air to sort grains according to density. The

angle of the deck, which is made of fine mesh, can be adjusted, as can the air

pressure, vibration, and flow rate of incoming seed. Before grain reaches the gravity

table, it should be sorted by size and shape, so that the batch of grain will form a ½”

thick layer of similar seed. The denser seed settles to the bottom of the layer while

less dense seed stratifies to the top and then slides “downhill” on the slippery seed

surface, moving the plumpest, densest kernels to the “uphill” side of the table. Baffles

on the surface of the deck preventing seed from moving across the table too quickly.

The paddles at the front of the table can be adjusted to divert grain of different

densities into separate containers.

3. Magnetic separator – it separates seed according to its surface texture or related seed

characteristics. First, seed is treated with iron filings, which adhere to rough surface

alone. The treated seed lot is passed over a revolving magnetic drum and separated

from smooth, uncoated seed. It may help to add varied amounts of water while mixing

seed and powder, depending on the seed type. At any rate, the effectiveness of

magnetic separation depends on the components of the seed lot and on the powder and

water used in the treating operation. The greater the difference between surface

textures of the seed components, the more effective will be the separation; it’s the

Principle of function Magnetic separator.

4. Colour separator – it is used to separate discoloured seed, greatly of lower quality.

Separation based on colour is necessary because the density and dimensions of

discoloured seed are the same as those of sound seed, so other machines are not

effective for separation. Electronic colour separation uses photocells to compare the

seed colour with the background which are selected to reflect the same light as the

good seed. Seed that differs in colour is detected by the photo cells, which generate an

electric impulse. The impulse activates an air jet to blow away the discoloured seed.

Separating Seed by Colour is done by use of the colour sorter which makes use of an

electronic eye that can pick up different colours according to the way the machine is

32

adjusted. As seed falls down a shoot, it passes through the electric eye. If the colour of

the seed is different than the desired colour, the electric eye will activate a sudden

burst of air that pushes that seed into a reject bin while the rest of the seed passes

through to another bin.

5. Colorsorter Friction cleaning - The air-screen combinations cannot remove debris

that has a size and density similar to the seeds. However, if the debris has a different

surface texture, it may be possible to remove by friction cleaning. Any object rolling

or sliding over a sloping surface encounters a certain friction depending on the texture

of itself and that of the sloping surface. Separation is made on a velvet cloth or rubber

belt with variable inclination, which ensures that the slope necessary for the run off of

the seed is different from the slope necessary for run -off of the debris. The belt

continuously moves upwards and removes the debris while the seeds roll down the

slope.

6. Spiral separator:- The separator, which classifies seed according to its shape and

rolling ability, consists of sheet metal strips fitted around a central axis in the form of

a spiral. The unit resembles an open screw conveyor standing in a vertical position.

The seed is introduced at the top of the inner spiral. Round seeds roll faster down the

incline than flat or irregularly shaped seeds, which tend to slide or tumble. The orbit

of round seed increases with speed on its flight around the axis, until it rolls over the

edge of the inner flight into the outer flight where it is collected separately. The

slower moving seed does not build up enough speed to escape from the inner flight.

Most spirals have multiple inner flights arranged one above the other to increase the

capacity.

7. Spiral Liquid flotation:- Cleaning by flotation relies on the principle that the density

of the seed of a given species is specific both for filled and ill filled seed. In this

method, liquids with a density or specific gravity between that of the full and empty

seed are used. The specific gravity of the liquids used is such that the full seed sinks

and the empty seed and light debris float. Calibrating seeds is important if you want to

pack seeds by weight, to create uniformity in young plants and for precision sowing

equipment. Belt graders are used to separate round from other shaped seeds/parts or

weeds in herb, vegetable and field seeds. E.g. separation of flat seeds, sticks and

weeds in basil, spinach, beet, lamb’s lettuce or cabbage seeds. This unique sorting

system can increase the seed lots purity. Also available with double or triple belts fo r

more capacity.

33

2.2.2 Seed spiral separator: - This machine is used to separate round seeds from other

shaped seeds/parts. E.g. separate ground from cabbage seeds, round from sharp spinach seed

and cleavers and very flat seeds from radish. The following weeds are removed from

cabbage: sine’s grass, triangular shaped seeds, black bind-weed and sorrel. Seed air screen

cleaning machines:-This air screen cleaning machine is very suitable for cleaning your

flower, herb, grain and vegetable seeds on their size and specific weight. It can be used for

medium size seed lots for pre- or fine cleaning. By means of the screens you can separate

straws, chaffs, dust and broken seeds. With the air separation system you can separate the

heavy from the light seeds.

Seed polishing machine is used for polishing medium large seed lots in bags. Because of the

gentile polishing process the machine is suitable for certain vegetable seeds like squash

(separate membrane), melon and tomato seeds.

Seed de-awner is used for de-bearding and polishing of seeds. The principle is mainly used

for certain vegetable seed crops like carrot, spinach, beet and tomato. In this machine the

seeds rub against each other and therefore the seed skin or beard is softly removed.

Figure 9: Amos single spiral cleaner

Gravity separator is used to separate your valuable grain and vegetable seeds based on their

specific weight. These machines are used for fairly large seed lots. The purpose is to separate

empty seeds, insect damaged seeds, stones and other lighter or heavier materials from the

seed lot

34

Figure 10: High Mowing's Oliver 30 gravity table.

The magnet is fitted within the outer layer to help remove the iron part which is

responsible for the processing down time. The choice of seed cleaner is depends on

which seeds one is processing.

HULLER SHAKER (Decorticator) - The system is a process for the Hulling and

Separating of Seed for oil production. Huller Shaker is a machine where kernel is

separated from the hulls. this process is mainly used in case of Cotton Seed /

Sunflower. By adding the decorticator production is increase and maintenance of

machine decrease. Machines worm run more time when seed is decorticated. For

Ground nut different type of decorticator are used to remove kernels and separate

husks

35

CHAPTER 3:

3.1.0 Design of a sunflower seed cleaner

Sunflowers are cultivated all over the world. It is one of the important crops. The seeds of

sunflower are very useful. Extraction of seeds, sunflowers, are dried in sunlight after which

they are rubbed over each other, the seeds that with which waste material are collected are

separated with wind which is passed over the seed, which is manual operation. This is time

consuming and laborious process.

Problem statement

The major problems faced by regional farmers in sunflower seed cleaning currently are;

laborious, time consuming and results in damages of the seeds. It is also very costly. Our aim

is to design for fabrication of a machine that will reduce above disadvantages in a best

possible way.

3.1.1 METHODOLOGY

We proposed the use of DC motor from which power is transmitted vertically by using gear

arrangement. This power is transmitted to rim on which flowers are splashed; this is mainly

flowers with husk and seeds.

The fan is provided for cleaning husk from seeds. Only seeds are obtained with minimum

effort and in less time.

Shafts are extensively used in machines and numerous engineering components including

gearboxes. Failures of shafts not only result in replacement cost, but also in process

downtime. This could have a drastic effect on productivity and, more importantly, late

delivery. Shaft failures may result from many causes including faulty designs, improper

applications and manufacturing errors . Design errors include such things as improper gear

geometry, poor materials quality, in-appropriate lubrication system. Application errors

include things such as improper mounting and installation, inadequate lubrication, and poor

maintenance.

Manufacturing errors could be poor machining or faulty heat treatments. An important

characteristic of production processes is the process reliability. This includes achieving the

required quality of each seed during single or multiple batch process.

36

PROPOSED WORK

Conventional seed cleaning methods analysis.

Search for the alternative types of seed cleaning methods.

Selection of the conveying method.

Design of parts.

Fabrication of components.

Final Result and conclusion.

3.1.2 CONCEPT

This is semi-operated type of machine. An operator switches on the electric supply, as the

motor start rotating its motion is transferred to horizontal shaft with the help of a motor

pulley by means of V-belt then; the horizontal shaft motion is transferred to the fan using a v-

belt (from which air is blown through the sieves) by a pulley connected to the horizontal

shaft, also the horizontal shaft motion is transferred through the vertical shaft from coupled

right angle bevel gears. At bevel gear motion goes in both directions first goes to, at the end

of vertical shaft to the rim, which is having 40 spokes and from the bevel gear another

horizontal shaft is connected to another bevel gear and a pulley that is attached to a rotating

mass fixed at the top-most sieve as a result causing vibration whereby machine is running

uniformly. Machine start completely running at the time the dried sunflower held by hand

and on a rotating rim which then rubs the flower on spokes, the seeds get extracted with husk

(waste material) which are collected in box or tray, in order to avoid splashing of seed the

section is enclosed by a box. The tray having slope and machine vibrating, the seeds and

waste materials path is in front of fan, which is belted with pulley mounted on horizontal

shafts, the fan blows air due to weight of seeds, these seeds falls down and get collected at

bottom of the tray, the light material of husk is thrown out and the process completed. In

these process, the sunflower is held on rotating rim for 4-5hrs while the seeds get more

collected in tray in less time.

37

3.1.3DESIGN OF PARTS

1.) VERTICAL SHAFT: - A shaft is the component of a mechanical device that transmits

rotational motion and power. Also defined as a rotating member which has a circular cross-

sectional. The shaft maybe hollow or solid. It is supported on bearings and it rotates a set of

gears or pulleys for the purpose of power transmission. The shaft is generally acted upon by

bending moments, torsion and axial forces.

SHAFTS VERSUS AXLE AND SPINDLE

Axle is a non-rotating member used for supporting rotating wheels, etc., and do not transmit

any torque. Spindle is simply defined as a short shaft. However, design method remains the

same for axle and spindle as that for a shaft.

Shaft design involves;-

Material selection: - Many shafts are made from low carbon, cold-drawn or

hot rolled steel. Alloy steel (Nickel, chromium and vanadium) are some of the

common alloying materials. However, alloy steel is expensive. Shafts usually

do not need to be surface hardened unless they serve as the actual journal of

bearing surface.

Geometric layout: - Geometry of any shaft is generally that of stepped

cylinder, hence there is no magic formula to give the shaft geometry for any

given design situation.

Shoulders are used for axially locating shaft elements and to carry any thrust

loads. Common torque transfer elements include; keys, set screws, pins, press

or shrink fits, tapered fits.

Stress and strength: static and fatigue. Shaft design based on strength is

carried out so that stress at any location of the shaft should not exceed material

yielding.

38

Stress due to torsion:

: Shear stress due to torsion

: Torque on the shaft

NOTE:

Bending stress:

M: Bending moment at the point of interest

do: Outer diameter of the shaft

c: di/do

Axial stress:

Fa: Axial force (tensile or compressive)

: Column-action factor(=1.0 for tensile load)

39

arises due to the phenomenon of buckling of long slender members which are

acted upon by axial compressive loads.

n =1.0 for hinged end ; n= 2.25 for fixed end

n =1.6 for ends partly restrained, as in bearing,

L = Shaft length

= yield stress in compression

Maximum shear stress theory (ductile materials):

Failure occurs when the maximum shear stress at a point exceeeds the

maximum allowable shear stress for the material. Therefore,

Maximum normal stress theory (brittle materials) :

]

40

Von Mises/ Distortion-Energy theory:

ASME design code (ductile material):

Where and are bending and torsion factors accounts for shock and

fatigue. The values of these factors are given in ASME design code for shaft.

ASME design code (brittle material):

]

41

ASME design code:

Combined shock and fatigue factors

Type of load Stationary shaft Rotating shaft

Gradualy applied load 1 1 1.5 1

Suddenly applied load, minor shock 1.5-2.0 1.5-2.0 1.5-2.0 1.0-1.5

Suddenly applied load, heavy shock --- --- 2.0-3.0 1.5-3.0

Commercial steel shafting:

= 55mpa for shaft without keyway

= 40 mpa for shaft with keyway

Steel under definite specifications:

= 30% of the yield strength but not over 18% of the ultimate strength

in tension for shafts without keyways. These values are to be reduced by 25%

for the presence of keyways.

Typical sizes of solid shafts that are available in the market are:

Diameter Increments

Up to 25mm 0.5mm

25 to 50mm 1.0mm

50 to 100mm 2.0mm

100 to 200mm 5.0mm

42

Example: Problem

A pulley drive is transmitting power to a pinion, which in turn is transmitting

power to some other machine element. Pulley and pinion diameters are 400 mm

and 200 mm respectively. Shaft has to be designed for minor to heavy shock.

Solution:

N.mm

OR

= N.mm

43

Bending (vertical plane):

= ((1000 200)-(6000 (400+200)))/(200+400+200)= -4250 N

= -4250 200 = -8.5e5 N.mm

= (6000 400)-(4250 600)

= -1.5e5 N.mm

Bending (horizontal plane):

= (5000 200)+(2200 (400+200)))/(200+400+200)

=2900N

= 2900 200 = 5.8e5 N.mm

= (2900 600) – (2200 400) = 8.6e5 N.mm

Bending (resultant) :

=10.29 N.mm

Similarly,

44

= 8.73 N.mm

Since and , section –D is critical.

ASME code:

Under minor to heavy shock, let us consider =2 and =1.5. Also let us

assume the shaft will be fabricated from commercial steel,

i.e. =40mpa.

=

= 65.88mm

The value of standard shaft diameter is 66mm

Deflection and rigidity: bending deflection, torsional twisting, slope at

bearings and shaft supported elements, and shear deflection due to transverse

loading on short shafts

Vibration: critical speed

45

2.) DESIGNING OF GEARS:

TYPES OF GEARS;

46

There are three categories of gears in accordance with the orientation of axes.

47

Characteristics of Each Type of Gears

Spur Gear: - Their Teeth are straight and parallel to shaft axis. Transmits power and motion

between two rotating parallel shafts.

Features

Easy to manufacture.

There will be no axial force. Relatively easy to produce high quality gears.

The commonest type. Applications Transmission components

Helical Gear: -Teeth are twisted oblique to the gear axis. Left, Helix angle, Right, Left The hand of helix is designated as either left or right.

Right hand and left hand helical gears mate as a set. But they have the same helix angle.

Features Has higher strength compared with spur gear.

Effective in reducing noise and vibration compared with spur gear.

Gears in mesh produce thrust forces in the axial directions. Applications

Transmission of power to components, automobile, speed reducers etc.

Rack: - The rack is a bar containing teeth on one face for meshing with a gear. The basic rack form is the profile of the gear of infinite diameter. Racks with machined ends can be joined

together to make any desired length.

Features Changes a rotary motion into a rectilinear motion.

Applications Its a transfer system for machine tools, printing press, robots, etc.

Internal Gear: - It is an annular gear having teeth on the inner surface of its rim.

The internal gear always meshes with the external gear.

Features

In the meshing of two external gears, rotation goes in the opposite direction while, In the meshing of an internal gear with an external gear the rotation goes in the same direction.

Care should be taken to the number of teeth when meshing a large (internal) gear with a small (external) gear, since three types of interference can occur.

Usually internal gear is driven by external (small) gear.

Allows compact design of the machine.

48

Applications

Planetary gear drive of high reduction ratios, clutches etc.

Bevel Gear

1. Straight Bevel Gear: -A simple form of bevel gear having straight teeth which, if extended inward, would come together at the intersection of the shaft axes.

Features

Relatively easy to manufacture.

Provides reduction ratio up to approx. 1:5. Applications Machine tools, printing press, etc. Especially suitable for a differential gear unit.

2. Spiral Bevel Gear: -A Bevel gear with curved, oblique teeth to provide gradual engagement and brings more teeth together at a given time than an equivalent straight bevel gear.

Features

Have higher contact ratio, higher strength and durability than an equivalent straight

bevel gear. Allows a higher reduction ratio.

Has better efficiency of transmission with reduced gear noise. Involves some technical difficulties in manufacturing.

Applications One of a pair of gears used to connect two shafts whose axes intersect, and the pitch surfaces are cones. Teeth are cut along the pitch cone. Depending on tooth trace bevel gear and is classified as:

Pitch cone

1) Straight bevel gear 2) Spiral bevel gear (above two are used for Automobile, tractor, vehicles, final

reduction gearing for ships.) 3. Miter Gears: -A special class of bevel gear where the shafts intersect at 90° and the

gear ratio is 1:1. 4. Screw Gear 5. Worm Gear Pair 6. Worm 7. Worm Wheel

A helical gear that transmit power from one shaft to another via either a non-parallel or non-intersecting shafts. Features

Used in a speed reducer and/or a multiplying gear.

Tends to wear as the gear come in sliding contact.

Not suitable for transmission of high horsepower.

49

Applications

Driving gear for automobile, automatic machines that require intricate movement. Worm gear is a shank having at least one complete tooth (thread) around the pitch surface;

the driver of a worm wheel. Worm wheel is a gear with teeth cut on an angle to be driven by a worm.

Features

Provides large reduction ratios for a given center distance. Quiet and smooth action.

A worm wheel is not feasible to drive a worm except for special occasions. Applications Speed reducers, anti-reversing gear device making the most of its self-locking features, machine tools, indexing device, chain block, portable generator, etc.

Gear parts:

Machine Design II

50

BEVEL GEARS

Bevel gears transmit power between two intersecting shafts at any angle or between non-

intersecting shafts. They are classified as straight and spiral tooth bevel and hypoid gears as in Fig.13.1

BEVEL GEAR STRAIGHT BEVEL GEAR

SPIRAL BEVEL GEAR HYPOID GEAR

51

GEOMETRY AND TERMINOLOGY

Bevel gear in mesh

When intersecting shafts are connected by gears, the pitch cones (analogous to the pitch cylinders of spur and helical gears) are tangent along an element, with their apexes at the

intersection of the shafts as shown in the diagram below where two bevel gears are in mesh.

The size and shape of the teeth are defined at the large end, where they intersect the back cones. Pitch cone and back cone elements are perpendicular to each other. The tooth profiles resemble those of spur gears having pitch radii equal to the developed back cone radii and and are shown in the figure below which also explains the nomenclatures

of a bevel gear.

52

Where is called the virtual number of teeth, p is the circular pitch of both the imaginary

spur gears and the bevel gears. and are the number of teeth on the pinion and gear, and are the pitch cone angles of pinion and gears. It is a practice to characterize the

size and shape of bevel gear teeth as those of an imaginary spur gear appearing on the developed back cone corresponding to Tredgold’s approximation.

Machine Design II a) Bevel gear teeth are inherently non - interchangeable.

b) The working depth of the teeth is usually 2m, the same as for standard spur and helical gears, but the bevel pinion is designed with the larger addendum ( 0.7 working depth).

Hence avoiding interference and results in stronger pinion teeth. It also increases the contact ratio. d) The gear addendum varies from 1m for a gear ratio of 1, to 0.54 m for ratios of 6.8 and greater. The gear ratio can be determined from the number of teeth, the pitch diameters or the pitch cone angles as,

Accepted practice usually imposes two limits on the face width

b 10m and b

53

Where L is the cone distance. Smaller of the two is chosen for design.

Illustration of spiral angle

The Fig. above illustrates the measurement of the spiral angle of a spiral bevel gear. Bevel gears most commonly have a pressure angle of , and spiral bevels usually have a

spiral angle of .

Above is an illustration of Zero bevel gears, which are having curved teeth like spiral bevels. But they have a zero spiral angle.

54

DIFFERENT TYPES OF BEVEL GEARS: a.) usual form, b.) Miter gears c.) , d.), e.) Crown gears f.)

Internal bevel gears

FORCE ANALYSIS:

55

Gear and shaft forces

Bevel gear - Force analysis

In Fig. above, Fn is normal to the pitch cone and the resolution of resultant tooth force Fn into its tangential (torque producing), radial (separating) and axial (thrust) components is designated Ft, Fr and Fa respectively. An auxiliary view is needed to show the true length of

the vector representing resultant force Fn (which is normal to the tooth profile).

56

Linear tooth force distribution

Resultant force Fn is shown applied to tooth at the pitch cone surface and midway along

tooth width b. It is also assumed that load is uniformly distributed along the tooth width despite the fact that the tooth width is larger at the outer end.

Where is in meters per second, is in meters, n is in revolutions per minute, is in

N and W is power in kW.

For spiral bevel gear,

Where and is used in the preceding equation, the upper sign applies to a driving pinion

with right-hand spiral rotating clockwise as viewed from its large end and to a driving pinion with left-hand spiral rotating counter clock-wise when viewed from its large end. The lower

sign applies to a left-hand driving pinion rotating clockwise and to a driving pinion rotating

57

counter clockwise. Similar to helical gears, is the pressure angle normal measured in a

plane normal to the tooth.

TOOTH BENDING STRESS The equation for bevel gear bending stress is the same as for spur gears as shown below:

Where: - = Tangential load N M = module at the large end of the tooth in mm

b = Face width in mm J = Geometry form factor based on virtual number of teeth from graph figures h.)

and g.) below =Velocity factor

= Overload factor, = Mounting factor, depending on whether gears are straddle mounted

(between two bearings) or overhung (outboard of both bearings), and on the degree of mounting rigidity

Figure h.) Number of teeth in gear for which geometry factor J is desired, pressure angle 20 and

shaft angle 90

58

Figure g.)

Number of teeth in gear for which geometry factor J is desired, pressure angle 20, spiral angle 35 and shaft angle 90

59

Dynamic load factor, Overload factor,

Driven Machinery

Source of power Uniform Moderate Shock Heavy Shock Uniform 1.00 1.25 1.75

Light Shock 1.25 1.50 2.00 Medium shock 1.5 1.75 2.25

Mounting factor Km for bevel gears

60

PERMISSIBLE TOOTH BENDING STRESS (AGMA) Fatigue strength of the material is given by:

Where, ’ endurance limit of rotating-beam specimen = Load factor, = 1.0 for bending loads =size factor,= 1.0 for m < 5 mm and = 0.85 for m > 5 mm =surface factor, taken from Fig.13.15 based on the ultimate strength of the material and for cut, shaved, and ground gears.

=reliability factor given in table below = Temperature factor, = 1 for T= 120 and more than 120 , k < 1 to be taken from

AGMA standards.

61

Surface factor,

Reliability factor,

Reliability factor R 0.50 0.90 0.95 0.99 0.999 0.9999

Factor Kr 1.000 0.897 0.868 0.814 0.753 0.702

=fatigue stress concentration factor. Since this factor is included in J factor its value is 1. =Factor for miscellaneous effects. For idler gears subjected to two way bending, =1. For other gears subjected to one way bending, the value is taken from figure below use =1.33 for ut less than 1.4GPa.

Miscellaneous effects factor Km

62

Permissible bending stress is given by

Hence the design equation from bending consideration is,

Bevel gear surface fatigue stress can be calculated as for spur gears, with only two modifications.

CONTACT STRESS:

1.23 times the Cp values given in the Table below are taken to account for a somewhat more localized contact area than spur gears.

Elastic Coefficient Cp for spurs gears, in Pinion Material

(µ = 0.3 in all cases)

Gear material

Steel Cast iron Al Bronze Tin Bronze

Steel, E=307GPa 191 166 162 158 Cast iron, E =131GPa 166 149 149 145

Al Bronze, E = 121GPa 162 149 145 142

Tin Bronze, E = 110GPa 158 145 141 137 Surface fatigue strength of the material is given by,

Where;

= surface fatigue strength of the material given in the table below

= Life factor given in Fig.v/)

63

Surface fatigue strength (MPa) for metallic spur gear, ( cycle life 99% reliability and

temperature < 120 )

LIFE FACTOR

64

K H is hardness ratio factor, K the Brinell hardness of the pinion by Brinell hardness of the gear as given in Figure below

K H = 1.0 for K < 1.2 K R = Reliability factor .

Indian Institute of Technology Madras

Hardness ratio factor, K H

K T = temperature factor, = 1 for T= 120 based on lubricant temperature. Above 120 , it is less than 1 to be taken from AGMA standards.

Allowable surface fatigue stress for design is given by [

Factor of safety s = 1.1 to 1.5 Hence Design equation is

65

3.) DESIGNING OF HELICAL SPRINGS;

Mechanical springs have varied use in different types of machines. We shall briefly discuss

here about some applications, followed by design aspects of springs in general.

Definition of a spring: Springs act as a flexible joint in between two parts or bodies

Objectives of spring: The main objectives of a spring when used as a machine member are

as follows:

1. Cushioning, absorbing, or controlling of energy due to shock and Vibration.

Car springs or railway buffers are used to control energy, springs-supports and

vibration dampers.

2. Control of motion

Maintaining contact between two elements (cam and its follower). In a cam and a

follower arrangement, widely used in numerous applications, a spring maintains

contact between the two elements. It primarily controls the motion. Also Creates the

necessary pressure in a friction device (a brake or a clutch). A person driving a car

uses a brake or a clutch for controlling the car motion. A spring system keep the

brake in disengaged position until applied to stop the car. The clutch has also got a

spring system (single springs or multiple springs) which engages and disengages the

engine with the transmission system.

Restoration of a machine part to its normal position when the applied force is

withdrawn (a governor or valve). A typical example is a governor for turbine speed

control. A governor system uses a spring controlled valve to regulate flow of fluid

through the turbine, thereby controlling the turbine speed.

3. Measuring forces; This achieved by use of spring balances, gauges

4. Storing of energy; - i.e. in clocks or starters - The clock has spiral type of spring

which is wound to coil and then the stored energy helps gradual recoil of the spring when in

operation. Nowadays we do not find much use of the winding clocks.

Before considering the design aspects of springs we took a quick look at the

Spring materials and manufacturing methods involved.

66

Commonly used spring materials

One of the important considerations in spring design is the choice of the spring material.

Some of the common spring materials are given below.

Hard-drawn wire:

This is cold drawn, cheapest spring steel. Normally used for low stress and static load. The

material is not suitable at subzero temperatures or at temperatures above .

67

Oil-tempered wire:

It is a cold drawn, quenched, tempered, and general purpose spring steel. However, it is not

suitable for fatigue or sudden loads, at subzero temperatures and at temperatures

above .

When we go for highly stressed conditions then alloy steels are useful.

Chrome Vanadium:

This alloy spring steel is used for high stress conditions and at high temperature up to

. It is good for fatigue resistance and long endurance for shock and impact loads.

Chrome Silicon:

This material can be used for highly stressed springs. It offers excellent service for long life,

shock loading and for temperature up to .

Music wire:

This spring material is most widely used for small springs. It is the toughest and has highest

tensile strength and can withstand repeated loading at high stresses. However, it cannot be

used at subzero temperatures or at temperatures above .

Normally when we talk about springs we found that the music wire is a common choice for

springs.

Stainless steel:

Widely used alloy spring materials.

Phosphor Bronze / Spring Brass:

It has good corrosion resistance and electrical conductivity. That’s the reason it is commonly

used for contacts in electrical switches. Spring brass can be used at subzero temperatures.

68

Spring manufacturing processes:

If springs are of very small diameter and the wire diameter is also small then the springs are

normally manufactured by a cold drawn process through a mangle.

However, for very large springs having also large coil diameter and wire diametermone has

to go for manufacture by hot processes. First, one has to heat the wire and then use a proper

mangle to wind the coils.

There are two major types of springs which are mainly used, helical springs and leaf springs.

In our case we have considered the design aspects of two types of springs.

Helical spring: -

The figures below show the schematic representation of a helical spring acted upon by a

tensile load F (Fig.1) and compressive load F (Fig.2). The circles denote the cross section of

the spring wire. The cut section, i.e. from the entire coil somewhere we make a cut, is

indicated as a circle with shade.

Figure 11: Helical spring

If we look at the free body diagram of the shaded region only (the cut section) then do we see

that at the cut section, vertical equilibrium of forces will give us force, F as indicated in the

figure. This F is the shear force. The torque T, at the cut sec tion and it’s direction is also

marked in the figure. There is no horizontal force coming into the picture because externally

there is no horizontal force present. So from the fundamental understanding of the free body

diagram one can see that any section of the spring is experiencing a torque and a force. Shear

force will always be associated with a bending moment. However, in an ideal situation, when

69

force is acting at the centre of the circular spring and the coils of spring are almost parallel to

each other, no bending moment would result at any section of the spring ( no moment arm),

except torsion and shear force.

Stresses in the helical spring wire:

Figure 12: Stresses in the helical spring wire

From the free body diagram, we have found out the direction of the internal torsion T and

internal shear force F at the section due to the external load F acting at the centre of the coil.

The cut sections of the spring, subjected to tensile and compressive loads respectively, are

shown separately in the Fig. below. The broken arrows show the shear stresses ( ) arising

due to the torsion T and solid arrows show the shear stresses due to the force F. It is

observed that for both tensile loads as well as compressive load on the spring, maximum

shear stress ( ) always occurs at the inner side of the spring. Hence, failure of the

spring, in the form of crake, is always initiated from the inner radius of the spring. As

indicated on the sketched figures below,

The radius of the spring is given by D/2. Note that D is the mean diameter of the spring.

The torque T acting on the spring is

70

If d is the diameter of the coil wire and polar moment of inertia,

, the shear stress in

the spring wire due to torsion is

Average shear stress in the spring wire due to force F is

Therefore, maximum shear stress the spring wire is

OR

OR

where, C=

,Is

called

the spring index.

Hence;

where,

The above equation gives maximum shear stress occurring in a spring. , is the shear stress

correction factor.

71

Stresses in helical spring with curvature effect

What is curvature effect? Let us look at a small section of a circular spring, as shown in the

Fig. Below Suppose we hold the section b-c fixed and give a rotation to the section a-d in the

anti clockwise direction as indicated in the figure, then it is observed that line a-d rotates and

it takes up another position, say a'-d'. The inner length a-b being smaller compared to the

outer length c-d, the shear strain Y at the inside of the spring will be more than the shear

strain at the outside of the spring. Hence, for a given wire diameter, a spring with smaller

diameter will experience more difference of shear strain between outside surface and inside

surface compared to its larger counterpart. The above phenomenon is termed as curvature

effect. So more is the spring index (C=

) the lesser it will be the curvature effect. For

example, the suspensions in the railway carriages use helical springs.

These springs have large wire diameter compared to the diameter of the spring itself. In this

case curvature effect will be predominantly high.

Figure 13: Stresses in helical spring with curvature effect

To take care of the curvature effect, the earlier equation for maximum shear stress in the

spring wire is modified as,

Where, is Wahl correction factor, which takes care of both curvature effect and shear

stress correction factor and is expressed as,

72

Deflection of helical spring

(B)

(A)

Figure 14: Deflection of helical spring

The Fig. 15 (A) and Fig. 15 (B) Shows a schematic view of a spring, a cross section of the

spring wire and a small spring segment of length dl. It is acted upon by a force F. From

simple geometry we will see that the deflection, d, in a helical spring is given by the formula,

Where, N is the number of active turns and G is the shear modulus of elasticity. The force F

cannot just hang in space, it has to have some material contact with the spring. Normally the

same spring wire e will be given a shape of a hook to support the force F. The hook etc.,

although is a part of the spring, they do not contribute to the deflection of the spring. Apart

from these coils, other coils which take part in imparting deflection to the spring are known

as active coils.

73

How to compute the deflection of a helical spring

Consider a small segment of spring of length ds, subtending an angle of dß at the centre of

the spring coil as shown in Fig. (B) above. Let this small spring segment be considered to be

an active portion and remaining portion is rigid. Hence, we consider only the deflection of

spring arising due to application of force F. The rotation, df, of the section a-d with respect to

b-c is given as,

The rotation, will cause the end of the spring O to rotate to O', shown in

Fig.(A). From geometry, O-O' is given as,

O-O'=

However, the vertical component of O-O' only will contributes towards spring deflection.

Due to symmetric condition, there is no lateral deflection of spring, i.e., the horizontal

component of O-O' gets cancelled.

The vertical component of O-O', d , is given as,

Total deflection of spring, , can be obtained by integrating the above expression for entire

length of the spring wire.

74

Simplifying the above expression we get,

The above equation is used to compute the deflection of a helical spring. Another important

design parameter often used is the spring rate. It is defined as,

Here we conclude on the discussion for important design features, namely, stress, deflection

and spring rate of a helical spring.

EXAMPLE

Problem

A helical spring of wire diameter 6mm and spring index 6 is acted by an initial load of

800N.

After compressing it further by 10mm the stress in the wire is 500MPa. Find the number of

active coils. G = 84000MPa.

Solution:

OR

Therefore sear force F =940.6

Hence, K=14N/mm

Or,

Hence,

75

4.) PROCESS DESIGN OF FANS AND BLOWERS.

Basic process engineering calculation related to fans and blowers such as interpretation of

performance curves, efficiency, power requirement, preparation of data sheets, etc. are

presented.

As a general rule, all gas compressing equipment which produce less than 135 kPa(abs.)

pressure at discharge, with an atmospheric (or slightly sub-atmospheric) suction pressure, fall

into the category of "Fans and Blowers".

DEFINITIONS AND TERMINOLOGY

Terms used in this standard are defined as follows:

a) Fan impeller

Is the assembly of the fan wheel and the hub(s). (API Std. 673, Section 1.4).

b) Fan plane

Is a flow area perpendicular to the flow of gas at the specified reference plane; that is, inlet

flange or outlet flange.

c) Fan rated point

Is defined as

(1) The highest speed necessary to meet any specified operating condition

(2) The rated capacity required by fan designs to meet all operating points. (The Vendor shall

select this capacity point to the best encompass specified operating conditions within the

scope of the expected performance curve.)

d) Maximum continuous speed (rotations per minute) Is the speed at least equal to the

product of 105 percent and the highest speed required by any of the specified operating

conditions.

e) Normal operating point

Is the point at which usual operation. Is expected and optimum efficiency is desired. Unless

otherwise specified, fan performance shall be guaranteed at the normal operating point.

f) The total pressure (P) of a fan

Is the rise of pressure from fan inlet to fan outlet as measured by two impact tubes, one in the

fan inlet duct and one in the fan discharge duct, corrected for friction to the fan inlet and

outlet respectively.

Where no inlet duct is used, total pressure on the inlet side is zero.

76

g) The velocity pressure ( Pv) of a fan

Is the pressure corresponding to the average velocity determination from the volume of air

flow at the fan outlet area.

h) The static pressure (P) of the fan

Is the total pressure (Ptf) diminished by the fan velocity pressure (P).

i) Standard air density

Is 1.2007 kg per cubic meter.

j) The unit of pressure

Is the mm. of water column of density of 997.423 kg per cubic meter and/or Pa (1 mm H2O

conventional= 9.80665 Pascal’s).

k) The volume handled by a fan

Is the number of cubic meters of air per hour expressed at fan outlet conditions.

l) The power output of a fan

Is expressed in kilowatts and is based on fan volume and fan total pressure.

m) The power input to a fan

Is expressed in kilowatts and is the measured kilowatt delivered to the fan shaft.

n) The mechanical efficiency of a fan

Is the ratio of power output to the power input.

o) The static efficiency of a fan

Is the mechanical efficiency multiplied by the ratio of the static pressure to the total pressure

or

77

p) The fan outlet area

Is the inside area of the fan outlet.

q) The fan inlet area

Is the inside area of the fan inlet collar.

r) Evase

Is a diffuser or a diverging discharge transition piece.

78

Fan Identification

Fans are rather generally identified as machines with relatively low pressure rises which

move air or gases or vapours by means of rotating blades or impellers and change the rotating

mechanical energy into pressure or work on the gas or vapour. The result of this work on the

fluid will be in the form of pressure energy or velocity energy, or some combination of both.

MAIN TYPES OF FANS

Ventilating and industrial fans are classified in four groups by the NAFM, National

Association of Fan Manufacturers as described below.

1 A Centrifugal Fan consists of a fan rotor or wheel within a scroll type of housing. The

centrifugal

Fan is designed to move air or gases over a wide range of volume and pressures. The fan

wheel may be furnished with straight, forward curve, backward curve, or radial tip blades.

The fan housing may be constructed of sheet metal or cast metals with or without protective

coating such as rubber, lead, enamel, etc.

2 A Vaneaxial Fan consists of an axial flow wheel within a cylinder combined with a set of

air guide vanes located either before or after the wheel. The Vaneaxial Fan is designed to

move air or gases over a wide range of volumes and pressures. It is generally constructed of

sheet metal although cast metal fan wheels are sometimes furnished.

3 A Tubeaxial Fan consists of an axial flow wheel within a cylinder. The Tubeaxial Fan is

designed to move air or gas through a wide range of volumes at medium pressures. Its

construction is similar to the Vaneaxial Fan.

4 A Propeller Fan consists of a propeller or disc wheel within a mounting ring or plate. The

Propeller Fan is designed to move air from one enclosed space to another or from indoors to

outdoors or vice versa in a wide range of volumes at low pressure. (The automatic type of

shutter illustrated in cut opposite is not a part of the Propeller Fan but is an auxiliary device to

protect the fan when not operating by keeping out wind, snow and cold).

79

DETAILED DESCRIPTIONS OF THE TYPES OF FAN

Centrifugal fans

There are three types of centrifugal fan blades (radial, backward and forward) which gives

three characteristic performances. Exact performance for a given fan can only be obtained

when testing the fan itself.

a) Radial blade

This type of blade is usually used for handling suspended materials, abrasive dust collecting

and exhausting of pumps from dirty, greasy or acid environment.

The rather sharply rising static pressure curve of the radial blade centrifugal fan allows for

small changes in volume as the resistance of the system changes considerably.

A Fair running static efficiency is 50-70 percent for both the straight radial blade and radial

tip blade.

b) Backward blade

This type of blade is well suited to stream line conditions and is used extensively on

ventilating, air conditioning and clean and dirty process gas streams. The outstanding and

important characteristic is the non-overloading power (kilowatts). It eliminates the need for

oversized motors or other drivers. The usual operating static efficiency range for the regular

blade is 65-80 percent and for the streamlined design is 80-92 percent.

c) Forward blade

This type is usually shallow and operates at slow speed for a given capacity and usually has

low outlet velocity.

Its operating characteristics are poor for many applications, since the power rises sharply with

a decrease in static pressure once the peak pressure for the fan has been reached.

The operating static efficiency range is 55-75 percent.

Axial flow fans

Its power characteristic is non overloading. The usual pressure range of application is 0-76

mm

80

Water (0-745 Pascal’s) static pressure. The vaneaxial and tubeaxial can be selected for higher

outlet velocities than the centrifugal (10.2 - 20.3 m/s).

The axial fans should be connected to ducts by tapered cone connection. The peak efficiency

range of the tubeaxial is 30-50 percent and for the vaneaxial is 40-65 percent.

Propeller fans

These fans usually operate with no piping or duct work on either side, and move air or gas

from one large open area to another. Pressures are usually very low and volumes depend

upon size, blade pitch, number of blades and speed.

Static efficiencies run from 10-50 percent depending on the fan and its installation. With well

designed inlet ring and discharge diffuser the efficiencies may be 50-60 percent.

Fan Laws

The performance of a fan is usually obtained from a manufacturer’s specific curve. Expected

performance for a change from one condition of operation to another, or from one fan size to

another .

Fan laws apply to blowers, exhausters, centrifugal and axial flow fans. The relations are

satisfactory for engineering calculations as long as the pressure rise is not greater than 7 kPa.

Theoretically a 100 mm water (0.98 kPa) pressure rise affects air density to cause a one

percent deviation. Where greater accuracy is required, the familiar adiabatic power relations

are used.

These laws are applicable only for geometrically similar fans and to the same point of rating

on the performance curve.

81

Performance Calculations

Pressure

a) Total System Pressure

The sum of the static and velocity pressure is the "Total System pressure" , P

(Eq. 1)

Where:

= is static pressure

= is velocity pressure

The fan total pressure Ptf, is measured as the increase in total pressure given to a gas passing

through a fan. It is a measure of the total energy increase per unit volume imparted to the

flowing gas by the fan. The static pressure is the fan total pressure than less the fan outlet

velocity pressure.

b) Velocity Pressure

mm of water or

pa

Where:

ρ is gas density

is gas velocity

Velocity pressure is indicated by a differential reading of an impact tube facing the direction

of air flow in the fan outlet. It is a measure of the kinetic energy per unit volume of gas,

existing at the fan outlet.

82

Peripheral velocity or tip speed

The peripheral velocity of the fan wheel or impeller is expressed as:

Where;

- is peripheral velocity

D – Is the wheel diameter

- is the rotational speed

Power:

a) Fan kilowatt based on total pressure:

Where: (FKW) is fan kilowatt

is inlet rate

b) Fan kilowatt based on static pressure output:

d) Shaft or brake kilowatt (input), based on direct current motor:

BkW= (Amp.)(Volts)(Motor efficiency)

e) Shaft or brake kilowatt (input), based on alternating current (3-phase) motor:

BkW= 3(Amp.)(Volts)(Motor efficiency)(Power factor)

Efficiency

a) Mechanical (total) efficiency:

83

b) Static efficiency

Temperature rise

The temperature rise as the gas passes through a fan is given by:

Where:

– is the temperature rise

- is air or gas temperature at fan inlet

– is fan outlet static pressure

- is atmospheric pressure or fan inlet pressure (if not atmospheric)

- is fan outlet velocity pressure

K - is ratio of specific heats,

Fan Control

Fan volume is controlled by the following methods:

a) Variable Speed Drive

This type of control can be accomplished by turbines, DC motors, variable speed motors or

slip-ring motors.

With changing speed of the driver the fan output capacity and pressure can be varied. For

capacity reductions below 50 percent, an outlet damper is usually added to the system.

b) Outlet Damper with Constant Fan Speed

The system resistance is varied with this damper. The volume of gas delivered from the fan is

changed as a function of the movement of the damper. It is low in first cost and simple to

operate, but does require more power than other methods of control.

84

c) Variable Inlet Vane with Constant Fan Speed

The angle and/or extent of closure of the inlet vanes controls the volume of gas admitted to

the inlet of the wheel.

The inlet vane control is more expensive than the outlet dampers but this can usually be

justified by lower kilowatt costs, specially on large power installations.

d) Fluid Drive

This method allows fan speed to be adjusted 20-100 percent with corresponding volume

changes. A constant speed motor is used, see Fig. 1, note that curve F of this figure is the

actual power input to the fan shaft. The hydraulic of fluid drive has about 3 percent in losses,

so its power input at 100 percent load is actually about 103 percent to allow for this.

Curves B and C are for variable vane inlet dampening and Curve A is for outlet dampening of

a backward blade fan. Curve E shows an outlet damper with multiple step speed slip-ring

motor. This has outlet damper for final control from 89-100 percent. From this graph a

reasonably accurate selection can be made of the control features to consider for most

installation conditions.

Figure 15: Comparison of efficiencies of five principal methods of controlling fan output

Fan Systems

An operating fan is a part of some system. Regardless of the system, the fan cannot be

selected until the flow and resistance characteristics have been analyzed. Fan selection for the

system is based on the static pressure for a given volume of gas flowing. Since most fans

85

operate at relatively low pressures the effect of uncertainty or error in resistance calculations

can have a large percentage effect on Kilowatt and operational characteristics. Since it is

essentially impossible to determine exact figures for the system resistances. It is to add 10-20

percent to the calculated static pressure as a safety factor.

Fan Selection Procedure

The following steps should be followed in fan selection.

a.) Specify the fan type

Information’s presented in sections above may help in selecting the suitable fan for the

process. Fan type curves should also be studied in order to recognize the effects of changes in

system resistance on the fan performance and the volume and pressure changes caused by

variations on speed. Recommendations of manufacturers are of particular importance in this

stage.

b.) Specifying the inlet volume

The volume of a fan should be determined by (1) the process material balance plus

reasonable extra (about 20 percent) plus volume for control at possible future requirement,

(2) generous capacity for purging, and (3) process area ventilation composed of fume hoods,

heat dissipation and normal comfort ventilation.

C.)System resistance

The system resistance must be calculated in the usual manner and at the actual operating

conditions of the fan.

Corrections are then applied to convert this condition to "standard" for use in reading the

rating tables.

d.) Manufacturers multi-rating tables

The multi-rating tables (rating tables) of fan manufacturers are convenient for selecting any

of the many types of fans. Usually m3 /h values can be found close enough to requirements to

be acceptable. Direct interpolation in the table for volume, r/min and BkW is acceptable for

narrow ranges; otherwise the fan laws must be used.

Performance tables are based on dry air at 21°C at sea level (barometric pressure 760 mm

mercury) with a density of 1.2 kg/m3

When the fans are required to handle gases at other conditions at the inlet, corrections must

be made for temperature, altitude and air or gas density.

86

f.) Performance at conditions other than above:

1) Calculate actual density of gas (or air) under operating conditions.

For Air, Fig. 2 is convenient to use: Read temperature correction factor, F1

Read altitude correction Factor, F2

at operating conditions

For gases other than air the density must be calculated since the curves of Fig. 2 are for an air

density of 1.2 kg/m3. If the gas density at 21 °C and 101.325 kPa is close to that of air under

these conditions, then the curves could be used for convenience. Otherwise, calculate the

actual gas density by the gas laws.

2) Calculate the equivalent static pressure which is given by:

3) The correct performance at the actual operating conditions will be: m3/h as set at inlet

conditions

Static pressure as set at inlet conditions, mm of water

Temperature as set at inlet conditions, °C.

r/min as read from manufacturers’ tables.

BkW as corrected by (5) above.

Example 1: Fan Selection

A system requires 10300 m3/h of air at 205°C against a 52 mm H2O static pressure. The

installation is at elevation 430 meters.

a) Determine: what type of fan blading should be used. A backward-curved blade fan will be

selected for this installation because the following are not known:

The accuracy with which the system characteristic of 52 mm of water at 10300 m3/h

was determined,

The type of process control to be used, and

The possible system variation.

A backward-curved blade will take care of the above unknowns. It will have:

1) High efficiencies. It is a blade that offers flexibility by inherently providing high

efficiencies over a wide range. It has its highest efficiency near its maximum kWpower.

This gives flexibility above and below the design point.

87

2) Non-overloading characteristics. A backward-curve blade will allow close "motoring"

without fear of overloading in the event of process upsets.

3) Steep static pressure curves . It offers a wide range of static pressures with a small change

in capacity.

b) Determine: can the 10300 m3/h at 205°C and against 52 mm of water, (2.04- inch) static

pressure be used to select a fan from the manufacturers’ tables?

The manufacturers’ tables are prepared in accordance with the industry standard set up by the

Air Moving and Conditioning Association. These tables are based on standard air.

1) Actual density of air at operating condition:

From chart, read at 205°C:

F1 = 0.74

Also read from the lower curve at 430 m altitude:

F2 = 1.15

Actual density = (0.74)(1.15)/1.2 = 0.709 kg/m3

Air density ratio = 0.709/1.2 = 0.59

2) Equivalent static pressure (at standard conditions):

=

3) Select fan from manufacturers’ performance table, at 88 mm of water and 10300m3/h.

Suppose that the nearest acceptable unit in the manufacturers’ table has the following

characteristics:

Inlet volume = 10330 m3/h

Speed = 2064 r/min at 88.9 mm H2O (3.5 inches).

BkW = 3.862 kW (5.18 hp) for standard air.

4) Actual r/min = 2064 (would be almost the same for actual conditions).

5) Actual BkW of fan = 3.862 (0.709/1.2) = 2.282 kW.

6) Performance at 430 m elevation and 205°C inlet air temperature will be:

Inlet volume = 10330 m3/h

r/min = 2064 (±)

BkW = 2.282 kW

88

Determine: could any other fan be used in this application? The next larger or smaller fan size

should be examined. Other manufacturers could possibly give a different size that might be

more efficient. The final selection should be based on an analysis of several different

manufacturers’ fans.

Determine: what is the tip speed of this fan?

Wheel diameter = 460 mm (18.5 inches).

Use Eq.

Where;

- is peripheral velocity

D – Is the wheel diameter

- is the rotational speed

Tip speed =

=

= 49.7 ms

Determine: what is the outlet velocity of the fan.

When quietness of operation is important, the outlet velocity should be in the range of 6 to 11

m/s.

The low outlet velocity corresponds to low outlet velocity pressure, and as this latter factor

directly influences power consumption. The velocity should be kept to a minimum,

particularly when the static pressure is low. However, it should be pointed out that very low

outlet velocity (less than 5m/s) are not really desirable because they produce no advantages,

not even quietness. Actual decibel ratings can be attained from the manufacturer, and these

are the best indication of actual noise level to be expected.

89

CLASSIFICATION OF VENTILATING AND INDUSTRIAL FANS

Figure 16: Classification of ventilating and industrial fans

In our case we have chosen to use axial fans since its more economical in terms of the surface

area it covers and quite affordable when you think of local users/farmers affordability when

summing the total cost of the machine itself

90

AXIAL FANS:

INTRODUCTION

The term axial flow fan indicates that the air flows through the fan in an approximately axial

direction. On the inlet side, as the flow approaches the fan blades, the direction of the flow is

axial, in other words, parallel to the axis of rotation, provided there are no inlet vanes or other

restrictions ahead of the fan wheel. The fan blade then deflects the airflow, as shown the fig.

1:

Figure 17: Airfoil as used in an axial flow fan blade [1]

91

I PROPELLER;

A propeller is a mechanism designed to produce a tractive force or push, when submerged in

a fluid medium. The propellers are aerodynamic elements that are composed of a hub or

central core and a number of blades.

The operating principle of axial- flow fans is simply deflection of airflow [2]. Past the blade,

therefore, the pattern of the deflected airflow is of helical shape, like a spiral staircase. This is

true for all three types of axial- flow fans: propeller fans, tube axial fans, and vane axial fans.

Accordingly, the design procedures and the design calculations are similar for all three types.

The helical pattern of the airflow past the blade of an axial flow fan the air velocity can be

resolved into two components: an axial velocity and a tangential velocity. The axial velocity

is the useful component. It moves the air to the location where we need it.

II. AIRFOIL

An airfoil is a streamline shape. Its main application is as the cross section of an airplane

wing. Another application is as the cross section of a fan blade.

There are symmetric and asymmetric airfoils. The airfoils used in fan blade are asymmetric.

Fig. 2 shows an asymmetric airfoil that has been developed by the National Advisory

Committee for aeronautics (NACA);

Figure 18: NACA 6512 airfoil obtained from Mat lab

As an airfoil moves through the air, it normally produces positive pressure on the lower

surface of the airfoil and negative pressure or suction on the upper surface [3]. The suction

pressure on the top surface are about twice as large as the positive pressures on the lower

surface, but all these positive and negative pressures push and pull in approximately the same

direction and reinforce each other. The combination of these positive and negat ive pressures

results in a force F.

92

This force F can be resolved into two components: a lift force L, perpendicular to the relative

air velocity; and a drag force D, parallel to the relative air velocity. The lift force L is the

useful component.

III. BLADE TWIST

For good efficiency, the airflow of an axial flow fan should be evenly distributed over the

working face of the fan wheel.

The axial air velocity should be the same from hub to tip. The velocity of the rotating blade is

far from evenly distributed: it is low near the centre and increases toward the tip. This

gradient should be compensated by a twist in the blade, resulting in larger blade angles near

the centre and smaller blade angles toward the tip. Fig. 3 shows an asymmetric airfoil as the

cross section of a fan blade.

Figure 19: An asymmetric NACA 6512 airfoil as the cross section of a fan blade

93

IV. NUMBER OF BLADES

Turbulence and noise are mostly produced by the edges, both leading and trailing edges and

not by the blade surface [4].

Therefore, fewer and wider blades will result in a better fan efficiency and a lower noise

level. But if the number of blades becomes too small and the blade width too large, the fan

cub becomes axially too wide and thus heavy, bulky, expensive, and hard to balance.

Aerodynamically, the optimal number of blades would be one very wide blade, draped

around the entry hub, but it would be an impractical and costly fan wheel. As a compromise

between efficiency and cost, five to twelve blades are good practical solution [5]. Fig. 4

shows a propeller fan.

Figure 20: NUMBER OF BLADES

As far as the point of design is concerned, the designer has a certain amount of freedom in

selecting the blade width at each radius can be compensated by corresponding variations in

the lift coefficient CL of the profile used in that section.

V. THE DIMENSIONS FOR AN AXIAL FLOW FAN

Let us consider a duct area

The requirements call for 60

(127133cfm) at a static pressure of 495 Pascal (2inWC) to be

produced by an axial fan at 2000rpm from an 84.438kw motor:

We can calculate the outlet velocity OV or q as:

94

Where; OV=q= dynamic pressure or outlet velocity

= at 2240m density altitude above sea level

V=local velocity

So

Q=AV and V=

Where:

Q= Volume of air

A= Duct area

V= Local velocity

The outlet velocity OV will be:

= 912 Pascal (3.661inWC)

The total pressure will be:

TP=SP + VP =495 +912=1407 Pascal (5.661inWC)

The air power will be:

P=Air Volume x Total Pressure

P=

) (1407 Pa) =84.438Kw

with an 84.438Kw motor this fan would have to have an 85 percent mechanical efficiency,

which is more than can be expected. This means that an 84.438Kw motor would be

overloaded. A 100.711Kw motor will be needed in order to get

at a static pressure of

495 Pascal.

95

Let us calculate the minimum hub diameter d Min and the minimum wheel diameter D Min

for these requirements.

The minimum hub diameter d Min will be

d Min=

We then calculate the minimum wheel diameter Dmin. This is given by

= 63.703in (1.618m)

VI. CONCLUSION

Once the necessity of fan design on a theoretical basis has been recognized, it is possible to

determinate the dimensions for a fan unit so that it will perform in accordance with a certain

set of specifications. The requirements for air volume and static pressure often determine

what type of fan should be used for a specific application.

The axial flow fan has the following advantages: compactness, low first cost, and straight

line Installation, little sound level at high tip speed.

96

4.) DESIGNING OF A V-BELT

The V-belts are made of fabric and cords molded in rubber and covered with fabric and

rubber, as shown in Fig (a). These belts are molded to a trapezoidal shape and arc made

endless- These are particularly suitable for short drives i.e. when the shafts are at a short

distance apart. The included angle for the V-belt is usually from 30° •- 403. In case of flat belt

drive, the belt runs over the pulleys whereas in case of V-belt drive, the rim of the pulley is

grooved in which the V-belt runs. The effect of the groove is to increase the frictional grip of

the V-belt on the pulley and thus to reduce the tendency of slipping. In order to have a good

grip on the pulley, the V-belt is in contact with the side faces of the groove and not at the

bottom. The power is transmitted by the * wedging action between the belt and the V-groove

in the pulley

Figure 21: V-belt and V-grooved pulley.

A clearance must be provided at the bottom of the groove, as shown in fig 22 (b). in order to

prevent touching to the bottom as it becomes narrower from wear. The V-belt drive, may be

inclined at any angle with tight side either at top or bottom, hi order to increase the power

output. Several V- belts may be operated side by side. It may be noted that in multiple V-belt

drive, all the belts should stretch at the same rate so that the load is equally divided between

them. When one of the set of belts breaks, the entire set should be replaced at the same time.

If only one belt is replaced, the new unworn and unstressed belt will be more tightly stretched

and will move with different velocity.

97

Advantages and Disadvantages of V-belt Driver Over Flat Belt Drive

Following are the advantages and disadvantages of the V-belt drive over flat belt drive

Advantages:

1. The V-belt drive gives compactness due 10 the small distance between she centres of

pulleys.

2. The drive is positive, because the slip between the belt and the pulley groove is

negligible.

3. Since the V-belts are made endless and there is no joint trouble, therefore the drive is

smooth

4. It provides longer life, 3 to 5 years

5. It can be easily installed and removed

6. The operation of the belt and pulley is quiet

7. The belts have the ability to cushion the shock when machines are started

8. The high velocity ratio (maximum 10) may be obtained

9. The wedging action of the belt in the groove gives high value of limiting ratio of

tensions.

Therefore the power transmitted by V-belts is more than flat belts for the same coefficient

of friction, are of contact and allowable tension in the belts.

10. The V-belt may be operated in either direction with tight side of the belt at the top or

bottom. The centre line may be horizontal, vertical or inclined.

Disadvantages

1. The V-belt drive cannot be used with large centre distances

2. The V-belts are not so durable as flat belts

3. The construction of pulleys for V-belts is more complicated than pulleys for flat belts.

4. Since the V-belts are subjected to certain amount of creep, therefore these are not

suitable for constant s[peed application such as synchronous machines, and timing

devices

5. The belt life is greatly influenced with temperature changes, improper belt tension and

mismatching of the belt lengths.

98

6. The centrifugal tension prevents the use of V-belts at speeds below 5 m/s and above

50 m/s

fig.23

Example: A belt drive consists of two Y-belts in parallel on grooved pulleys of the same

size. The angle of the groove is 30°. The cross-sectional area of each belt is 750 mm2 and M-.

= 0.12.

The density of the belt material is 1.2 Mg/m3 and the maximum safe stress in (he material is 7

MPa. Calculate the power that can be transmitted between pulleys 309 mm diameter rotating

at 1500 r.p.m. Find also the shaft speed in r.p.m. at which the power transmitted would be

maximum.

Solution;

Given : 2 β = 30 or 15o; a = 750 mm2 = 750 x 10-6; = 0.12; = 1.2 Mg/m3 = 1200 kg/m3;

= 7 MPa = 7 x 106 N/m2; d = 300- mm = 0.3 m; N = 1500 r.p.m

Power transmitted

We know that velocity of the belt

and mass of the belt per metre length,

m = area x length x density = 750 x 10-6 x 1 x 1200 = 0.9 kg/m

A V-belt with a grooved pulley is shown in Fig. 11.20.

Let R1 = Normal reaction between the belt and sides of the

groove.

R = Total reaction in the plane of the groove.

= Coefficient of friction between the belt and sides of the

groove.

Resolving the reactions vertically to the groove,

R = R1 sin β + R1 sin β = R1 = R1 sin β

R1

We know that the frictional force = 2 1 sin β + = R1 sin β = 2 R1 sin β

Consider a small portion of the belt. subtending an angle 58 at the

centre. The tension on one side will be T and on the other side T +

δT.

Now proceeding as in Art 11.14, we

get the frictional resistance equal to

.R cosec |3 instead of . A1. Thus

the relation between T1 and T2 for the

V-belt drive will be

2.3 log

= . cosec β

99

Therefore tension in the tight side of the belt,

T1 = T – Tc = 5250 – 500 = 4750 N

Let T 2 = Tension in the slack side of the belt

Since the pulleys are of the same size, therefore angle of contact, = 180o = rad.

We know that

2.3 log

= . cosec β = 0.12 x x cosec 15o = 1.457

log

=

= 0.6334 or

= 4.3

(Taking antilog of 0.6334)

and

We know that power transmitted,

P = (T1 – T2) v x 2 …(there No. of belts = 2)

= (4750 – 1105) 23.56 x 2 = 171 752.752 kW Ans.

When a belt is wound round the two pulleys (i.e. driver and follower), Us two ends are joined

together; so that the belt may continuously move over the pulleys, since the motion of the belt

from the driver and the follower is governed by a firm grip, due to friction between the belt

and the pulleys. In order to increase this grip, the belt is tightened up. At this stage, even

when the pulleys arc stationary, the belt is subjected to some tension, called initial tension.

When the driver starts rotating, it pulls the belt from one side (increasing tension in the belt

on this side) and delivers it. to the other side (decreasing the tension in the belt on that side),

The increased tension in one side of the belt is called tension in tight side and the decreased

tension in the other side of the belt is called tension in the slack side.

Let T, = Initial tension in the belt,

T-, = Tension in the slack side of the belt,

T2 Coefficient of increase of the belt, and

= Coefficient of increase of the belt length per unit force.

A little consideration will show that the increase of tension in the light side

= T1 - To

and increase in the length of the belt on the tight side

= (T1 — T o ) …(i

100

Similarly, decrease in tension in the slack side

= To – T2)

and decrease in the length of the belt on the slack side

= (To — T 2 ) …(ii)

Assuming that the belt material is perfectly elastic such that the length of the belt remains

constant, when it is at rest or in motion, therefore increase in length on the tight side is equal

to decrease in the length on the slack side. Thus, equating equations (/) and (e7),

(T1 – To) = a (To – T2) or T1 – To = To – T2

…(Neglecting centrifugal

tension)

…(Considering centrifugal tension)

Power Transmitted by a Belt

Figure 11.14 shows the driving pulley (or driver). A and the driven pulley (or follower) B.

we have already discussed that the driving pulley pulls the belt from one side and delivers the

same to the other side. It is thus obvious that the tension on the former side (i.e. tight side0

will be greater than the latter side (i.e. slack side) as shown in figure above).

Let T1 and T2 = Tensions in the tight and slack side of the belt respectively in Newton.

R1 and r2 = Radii of the driver and follower respectively, and

v = Velocity of the belt in m/s

the effective turning (driving) force at the circumference of the follower is the difference

between the two tensions (i.e. T1 – T2).

Therefore work done per second = (T1 – T2)v W … (therefore 1 N-m/s = 1 W)

A little consideration will show that the torque exerted on the driving pulley is (T1 – T2) r1.

Similarly, the torque exerted on the driven pulley i.e. follower is (T1 – T2) r2

101

5.) DESIGNING OF A ROTATING MASS.

UNBALANCE:

The condition which exists in a rotor when vibratory force or motion is imparted to its

bearings as a result of centrifugal forces is called unbalance or the uneven distribution of mass about a rotor’s rotating centreline.

Rotating centreline:

The rotating centerline being defined as the axis about which the rotor would rotate if not

constrained by its bearings. (Also referred to as the Principle Inertia Axis or PIA).

Geometric centreline:

The geometric centreline is the physical centreline of the rotor. When the two centrelines are coincident, then the rotor will be in a state of balance. When they are apart, the rotor will be unbalanced.

Different types of unbalance can be defined by the relationship between the two centrelines.

These include:

Static Unbalance – where the PIA is displaced parallel to the geometric centreline. Couple Unbalance – where the PIA intersects the geometric centreline at the centre

of gravity. (CG) Dynamic Unbalance – where the PIA and the geometric centreline do not coincide or

touch.

The most common of these is dynamic unbalance.

102

Causes of Unbalance:

In the design of rotating parts of a machine every care is taken to eliminate any out of balance or couple, but there will be always some residual unbalance left in the finished

slight variation in the density of the material or In accuracies in the casting or In accuracies in machining of the parts.

Why balancing is so important?

A level of unbalance that is acceptable at a low speed is completely unacceptable at a higher speed.

As machines get bigger and go faster, the effect of the unbalance is much more

severe. The force caused by unbalance increases by the square of the speed.

If the speed is doubled, the force quadruples; if the speed is tripled the force increas by a factor of nine!

Identifying and correcting the mass distribution and thus minimizing the force and resultant vibration is very very important

BALANCING:

Balancing is the technique of correcting or eliminating unwanted inertia forces or moments in rotating or reciprocating masses and is achieved by changing the location of the mass centers.

The objectives of balancing an engine are to ensure:

1. That the centre of gravity of the system remains stationery during a complete revolution of

the crank shaft.

2. That the couples involved in acceleration of the different moving parts balance each other.

Types of balancing:

a) Static Balancing:

i) Static balancing is a balance of forces due to action of gravity.

ii) A body is said to be in static balance when its centre of gravity is in the axis of rotation.

103

b) Dynamic balancing:

i) Dynamic balance is a balance due to the action of inertia forces.

ii) A body is said to be in dynamic balance when the resultant moments or couples, which

involved in the acceleration of different moving parts is equal to zero.

iii) Both the conditions of dynamic balance and static balance are met.

In rotor or reciprocating machines many a times unbalance of forces is produced due to inertia forces associated with the moving masses. If these parts are not properly balanced, the dynamic forces are set up and forces not only increase loads on bearings and stresses in the

various components, but also unpleasant and dangerous vibrations.

Balancing is a process of designing or modifying machinery so that the unbalance is reduced to an acceptable level and if possible eliminated entirely.

BALANCING OF ROTATING MASSES

When a mass moves along a circular path, it experiences a centripetal acceleration and a force

is required to produce it. An equal and opposite force called centrifugal force acts radially outwards and is a disturbing force on the axis of rotation. The magnitude of this remains

constant but the direction changes with the rotation of the mass.

In a revolving rotor, the centrifugal force remains balanced as long as the centre of the mass of rotor lies on the axis of rotation of the shaft. When this does not happen, there is an

eccentricity and an unbalance force is produced. This type of unbalance is common in steam turbine rotors, engine crankshafts, rotors of compressors, centrifugal pumps etc.

Figure 22: Balancing of rotating masses

The unbalance forces exerted on machine members are time varying, impart vibratory motion

and noise, there are human discomfort, performance of the machine deteriorate and detrimental effect on the structural integrity of the machine foundation.

104

Balancing involves redistributing the mass which may be carried out by addition or removal of mass from various machine members

Balancing of rotating masses can be of :

1. Balancing of a single rotating mass by a single mass rotating in the same plane.

2. Balancing of a single rotating mass by two masses rotating in different planes.

3. Balancing of several masses rotating in the same plane

4. Balancing of several masses rotating in different planes

STATIC BALANCING:

A system of rotating masses is said to be in static balance if the combined mass centre of the system lies on the axis of rotation

DYNAMIC BALANCING;

When several masses rotate in different planes, the centrifugal forces, in addition to being out

of balance, also form couples. A system of rotating masses is in dynamic balance when any resultant centrifugal force as well as resultant couple does not exist.

For our case we focus on a single rotating mass by a single mass rotating in the same plane

Figure 23: Single rotating mass by a single mass rotating in the same plane

Consider a disturbing mass m1 which is attached to a shaft rotating at ω rad/s.

105

Let radius of rotation of the mass m1 or the distance between the axis of rotation of the shaft and the centre of gravity of the mass m1.

The centrifugal force exerted by mass m1 on the shaft is given by,

This force acts radially outwards and produces bending moment on the shaft. In order to counteract the effect of this force Fc1, a balancing mass m2 may be attached in the same

plane of rotation of the disturbing mass m1 such that the centrifugal forces due to the two masses are equal and opposite.

Let, = radius of rotation of the mass or distance between the axis of rotation of the shaft and

the centre of gravity of the mass .

Therefore the centrifugal force due to mass will be,

Equating equations (1) and (2), we get

which implies;-

or

The product can be split up in any convenient way. As for as possible the radius of

rotation of mass m2 that is r2 is generally made large in order to reduce the balancing of mass m2.

Example

Four masses A, B, C and D are attached to a shaft and revolve in the same plane. The masses

are 12 kg, 10 kg, 18 kg and 15 kg respectively and their radii of rotations are 40 mm, 50 mm, 60 mm and 30 mm. The angular position of the masses B, C and D are 60 , 135 and 270

from mass A. Find the magnitude and position of the balancing mass at a radius of 100 mm.

Solution:

106

Given:

To determine the balancing mass `m' at a radius of r = 0.1 m.

The problem can be solved by either analytical or graphical method.

By Analytical Method:

Step 1:

Draw the space diagram or angular position of the masses. Since all the angular position of

the masses are given with respect to mass A, take the angular position of mass A as

The given data is as shown below on the diagram representation. Since the magnitude of the centrifugal forces are proportional to the product of the mass and its radius, the product `mr'

can be calculated and tabulated.

Step 2:

Resolve the centrifugal forces horizontally and vertically and find their sum.

Resolving horizontally and taking their sum gives,

Resolving vertically and taking their sum gives,

Resolving vertically and taking their sum gives

107

Step 3:

Determine the magnitude of the resultant centrifugal force

Step 4:

The balancing force is then equal to the resultant force, but in opposite direction. Now find

out the magnitude of the balancing mass, such that

Where, m = balancing mass and r = its radius of rotation

Step 5:

Determine the position of the balancing mass `m'.

108

If is the angle, which resultant force makes with the horizontal, then

The balancing force is then equal to the resultant force, but in opposite direction.

The balancing mass `m' lies opposite to the radial direction of the resultant force and the angle of inclination with the horizontal is , angle measured in the clockwise

direction as shown below.

By Graphical Method:

Step 1:

The data obtained was tabulated as shown above. Since the magnitude of the centrifugal forces are proportional to the product of the mass and its radius, the product ‘mr’ can be

calculated and tabulated.

109

Draw the space diagram or angular position of the masses taking the actual angles ( Since all angular position of the masses are given with respect to mass A, take the angular position of

mass A as )

Step 2:

Now draw the force polygon (The force polygon can be drawn by taking a convenient scale)

by adding the known vectors as follows.

Draw a line `ab' parallel to force (or the product to a proper scale) of the space diagram. At `b' draw a line `bc'parallel to (or the product ). Similarly draw lines

`cd', `de' parallel to (or the product ) and (or the product ) respectively. The

closing side `ae' represents the resultant force `R' in magnitude and direction as shown on the vector diagram.

Step 3:

The balancing force is then equal to the resultant force, but in opposite direction.

The balancing mass ‘m’ lies opposite to the radial direction of the resultant force and the

angle of inclination with the horizontal is, angle measured in the clockwise

direction.

110

VIBRATIONS:

Rotating Unbalance

We considered forced vibration due to the application of a sinusoidal force. A common

source of such a sinusoidal force is unbalance in a rotating machine or rotor. I t may have

been experienced if one has ever driven a car where the wheels are not balanced; one may

have noticed that at a particular speed, the car will shake, sometimes quite violently. At this

speed, the rotational speed of the wheels is such as to be close to the natural frequency of the

car on its suspension, so that the amplitude becomes a maximum. In our design we will look

at how we can describe such a phenomenon more precisely, in a mathematical way.

Rotating machines include turbines, electric motors and electric generators, as well as fans, or

rotating shafts. Rotating shafts experience a special kind of response, known as “whirl”.

Let us suppose that a rotating machine of mass m can be modeled as being mounted on a

spring of stiffness, k, to a fixed support, and that there is viscous damping in the system, with

a damping coefficient, c. We also supposed that the machine is constrained to move

vertically, so that this is a single degree-of- freedom system. The rotor is unbalanced if its

centre of mass does not coincide with the centre of rotation. Suppose that the unbalance can

be represented by a mass m at a distance e from the centre of rotation. (e is sometimes called

the eccentricity.) Let the angular speed of rotation of the rotor be .

The system is as illustrated below;

Figure 24: angular speed of rotation

After a time t, the out-of-balance mass will have moved through an angular displacement t.

If x is the displacement of the mass (m – mu) from the equilibrium position after a time t, the

displacement of the out-of-balance mass, mu, will be (x + esin t). The forces acting on the

111

combined mass are -kx and - c (i.e. they act in the opposite direction to the positive x-

direction).

The equation of motion is, therefore:

-kx- = (m-mu)

-kx- = m -mu

This can be written as m + + kx=

Now this is of the same form as the equation of motion for damped forced vibration which is

written as

m + + kx=

but F0 has been replaced by . So the excitation is due to an applied force, F0 ,

where F0 = . This is the centripetal force of the mass towards the centre of

rotation. If the rotor is balanced, e is 0, so this force does not exist. If e is only small the

amplitude of the exciting force is also small. The amplitude of the excitation depends on both

the out-of-balance mass, and its effective distance from the axis of rotation, as well as on the

rotational speed.

The response will be given by x = where

X0 =

=

=

.............. (1)

And tan =

=

........................................... (2)

And, as before, is the natural frequency,

,

and r =

112

If we write equation (1) in a non-dimensional form it is easier to see how in general the

response depends on the frequency ratio, r, and on the damping ratio . Re-writing equation

(1), therefore:

=

Figure below is obtained by plotting

against r.

Figure 25: plotting

against r

Hence the response of an unbalanced rotor as a function of the frequency

This shows that at low speeds, where r is small, and the amplitude of the motion of the mass

(m - m u) is nearly 0, while at very large values of r, the amplitude becomes constant, at a

value equal to em u /m, and it doesn’t matter what the damping in the system is at all, nor

does the actual speed. This explains why, if you are bold enough to speed up with your car

having unbalanced wheels it will begin to shake, the shaking stops, as the value of r becomes

much greater than 1.

The maximum amplitude occurs when r =

At resonance, when r = 1, the amplitude of the mass (m - m u) is

so its magnitude

is reduced if there is damping in the system.

113

At resonance, the phase angle = 90° and the response lags the excitation by 90°. This

means that when the mass (m – m u) is moving upwards through its position of equilibrium

the unbalance mass m u is directly above the centre of rotation.

A rotor can be balanced by placing a balancing mass, m b, on the rotor diametrically opposite

mu, and at a distance, h, such that mbh = mue.

This mass mb then produces an excitation force that is exactly equal and opposite to that

produced by the out-of-balance, so that there is no resultant excitation force.

Example

A 40 kg motor is similar to the system shown in Figure (1). It is supported by four springs

each of stiffness 250 Nm-1. The rotor is unbalanced such that the unbalance effect is

equivalent to a mass of 5 kg located 50 mm from the axis of rotation. Find the amplitude of

vibration and the force transmitted to the foundation when the speed of the motor is (a) 1000

rev/min, (b) 60 rev/min, The damping ratio, = 0.15.

Solution:

We know: m = 40 kg, k = 4*250 = 1000N/m, mu = 5 kg, e = 50 mm = 0.05 m, = 0.15

Speed of motor = 1000 rev/min

First we calculate the natural frequency and r:

, therefore r =

From equation (1).

=

=

So the amplitude of the vibration of the motor at 1000 rev/min is 6.3mm

114

From section 2,

= e

The amplitude of the force transmitted is 40 N.

and r =

The amplitude of the response is 14 mm and the force transmitted is 15 N.

In this case, the displacement amplitude is more than twice its value at the higher speed,

which means more than 4 times the peak-to-peak displacement.

The force transmitted to the foundations however has reduced. The more damping there is,

the less critical is resonant frequency as far as the force transmitted is concerned. With a

damping ratio of more than 0.1 the force transmitted is increased when the speed of rotation

increases.

Above example illustrates the problems that can arise during machine start-up.

Because as the speed gradually increases to the operating speed it will go through a point

when r is 1, and the amplitude of vibration can become momentarily large. If there is only a

small amount of damping in the system then the force transmitted can also become

significant.

115

CHAPTER FOUR:

4.1.0 DESIGN OF PARTS:

1) VERTICAL SHAFT:-

It is middle part of the machine. It is made of steel and supported by means of two bearings.

The shaft is supported with the square bar. At lower end of this shaft a bevel gear is fitted

which receives motion from the horizontal shaft. The upper end of this shaft rim is fitted so, it

gets the motion from that shaft.

Diameter of driving Pulley = D1 = 75

Diameter of driven Pulley= D2 = 230

R1 = 37.5mm

R2 = 115mm

Shear Stress = = 45N/mm²

Bending Stress = 75N/mm²

Speed of Motor Shaft = 1440rpm

What we do not know is the Speed of Horizontal shaft which we obtained from the following

calculations;

We know that,

Power of motor that we are using = 1 HP = 746.54 watt

Hence we first determine the rotational speed of horizontal shaft which is given by the

following formulae

N2/N1 = D1/D2

And since we know N1, D1, and D2 we can obtain N2 as follows:

N2/1440 = 75/230

Hence, N2 = 469.56rpm

We know that,

Torque transmitted by shaft is given by;

116

Making T subject we obtained, T= 4947N-mm

When we Consider power transmitted by motor

Theoretically, P = 75% motor power,

Therefore, Actual power is given by;

P (act.) =% of motor power power of motor itself which is,

P (act) = 0.75 746.54 hence actual power is 554.5 watts from above calculations

2) DESIGN OF BELT

Angle of contact of belt

Ѳ = p+2a

In order to calculate for a we used the formulae below,

a = sin-1 (

)

a = sin-1(37.5-

)

a = 14.47

Therefore,

Ѳ = ( +2a)

= 180+ (2 14.47)

Ѳ = 208.95

Belt tension ratio,

T1/T2 = e µ Ѳ

T1 = e (0.12 3.64)

T1 = 1.547 T2

We know the Torque transmitted by driven pulley,

T = (T1-T2) r

4947 = (1.54 (T1-T2)) 115

4947 = 62.99T2

Hence; T2 = 78.53N

Therefore,

T1 = 1.54 T2

T1 = 1.54 78.53

T1 = 121.49N

117

To obtain Maximum bending moment we used the formulae outlined below,

M = (T1+T2) X

M = (212.49+78.53) 310

M = 62.0006 10³ N-mm

Torque equivalent (Te) was also calculated as shown,

Te = 2+ (4947)2

Te = 62.203 10³ N-mm

Shearing stress subjected on driven shaft was also analysed as follows,

This implies,

Te = p d2/32=t/d/2

16Te/pd3 = t

=7039.96

D = 19.16mm

To find equivalent Bending moment we used the formulae given below;

Me = ½ (M + Te)

= ½(62.006+62.203) 103

Me = 62.10 10³ N-mm

We found out that, the Bending stress subjected on driven shaft is given by,

M/I = Bending stress/y

Therefore; -

32 62.10 103/ 705

8433.93

D = 20.35mm

Therefore,

We select maximum diameter of shaft which was about 20.35mm

d = 20.35mm

118

3) DESIGN OF BEVEL GEAR

Speed ratio = 1

Zg = Zp

Given rpm = 1440

Hp = 1 =0.75Kw

Assume,

Material = 40C8 (Sut=600 N/mm²), 400 BHN

Pressure angle =20°……..as full depth system.

Number of teeth =25

Zg =25

Zp =25

Factor of safety =2

As driving motor is uniform OR working characteristics of driven machine is uniform.

Service factor is 1.

Mt =4976.11 N/mm²

Now, Dp = 2Tp = m 25

Pt = 199.64

Initially for generating the teeth. Consider V= 5m/s

Therefore for gear below 10m/s. V< 10m/s.

Cv = 0.71

Peff =

For bevel gears,

b/ = 1/3 and b =10m

Tan = tan-1 =45

Pitch angle = 45

Zp =35.35 =35

119

From Levis form factor Y=0.373

Sb= m b b Y (1-b/A0)

=m (10m) (600/3)0.373(1-1/3)

=497.33 m²

Sb= Peff fs

497.33 m²= (560.68/m) 2

m=1.311.5………..preferred choice.

But the module here chosen is 2.

Main gear dimensions,

Dg = Dp = 25 2=50

A0= 35.35

For face width

b = 10m OR b/A0=1/3

b= A0/3

b = 10 2

= 20

OR

b = 35.35/3

= 11.78

= 12 mm

Smaller value of width is chosen.

Therefore taking b = 12 mm.

Correct factor of safety = Pt = 199.64N

Error for module up to 4mm class 3 grade, = 0.0125mm

V = 0.003768 m/s

From table, deformation factor C = 11400 N/mm².

Now, Pd =

V = 0.0037 m/s

e= 0.0125mm

b = 12mm

Pt = 199.64N

120

Pd = 160.409/43.7 = 3.66

Peff = (Cs Pt) + Pd

= (1 199.64 )+ 3.66

= 203.09N

Beam strength =

Sb = m b b Y (1-b/A0)

= 2 12 200 0.373(1-12/35.35)

= 1182.62N

Therefore factor of safety for bending consideration,

Fs = Sb/Peff

= 1182.62/203.09

Hence the design is safe as Sb>Peff.

Wear strength

K = 0.16(BHN/100)

= 2.56N/ mm².

Q = 1

Sw = 1129.174N

FACTOR Of safety against wear strength

= Sw/Peff

= 1129.174/203.09

Sw < Peff

Design is safe.

Forces on bevel gear

Rm = 20.7502mm

Pt = Mt/Rm =

= 239.81N

Ps = Pt tan 20 = 239.81 tan20 = 87.28N

Ps = separating force.

Pr = Ps cos 45= 87.28 cos 45 = 61.71N

Pa = Ps sin 45 = 87.28 sin 45 = 61.71N.

121

4.1.1 FABRICATION OF MACHINE

In every machine or any assembly it is of importance that, it is rigid in construction with

minimum cost. In our project we give more importance to the fabrication.

We proposed the use of 12 angles which are welded together to form rigid rectangular stand

as supports to the machine from the bottom.

The angle of M.S. Square bar are used to support the pipe in which vertical shaft is

mounted.

The rim should be mounted on a vertical which gives the extraction of sunflower

seeds.

The cover is provided to avoid the splashing of seeds outside the box.

The fan is fixed at angle behind the tapered opening of seeds from the tray to separate

seeds from husk.

The pulley is provided for the rotating the fan, which is driven by V-belt, which is

driven by horizontal shaft.

The tray should be made of sheet metal which should be mounted of at the top of the

machine used for purpose of collecting seed.

The box is made up of plywood to avoid the splashing of seed.

122

4.1.2 COST ESTIMATION OF THE MACHINE COMPONENTS:

NAME OF

PART

MATERIAL SIZE QUANTITY COST

Bevel Gear Mild Steel 25 teeth 3 3300

Horizontal

Shaft

Mild steel 24 750mm 1 530

Vertical Shaft Mild Steel 24 750mm 1 580

Fan Shaft Mild Steel 25 210mm 1 250

Bushing Mild Steel 1 200

Ball Bearing Mild Steel 6 800

Hub Mild Steel 2 600

Fan Plastic 1 80

Pulley 7.62cm 2 500

Fan Pulley 100

Motor Pulley 150

Plane Sheet 600

Angle 1000

V-Belt Rubber B52,B-45 2 200

Rim Stainless steel 40spokes 1 250

Bolt Mild Steel 24 20 100

Welding Rod 30 150

Paint 1 Litre 100

Square Bar 6 200

Fan Bushing 200

Motor 1 Hp 1 1200

Helical

Springs

4 800

Sieve/Screens Wire mesh 1m 1m(round hole

0.5in)

2 1600

Frame 1m 1m 4 2400

Pin rods

4 200

Sieve/screen 2 Wire mesh 1m 1m(rectangular

hole)

2 1200

TOTAL

COST 17,390/=

123

CHAPTER FIVE

5.1 RECOMMENDATION

In conclusion we as a team feel satisfied with what we have done in regards to bringing this idea to life, though we were not able to build a prototype a thing we so wanted to do,

we would like to recommend that if it’s possible others to look into actually building a model of such a machine, since all the requirements and specification is available as per

this report as well as variation limit is also accommodated depending on how small or large the prototype will be, though actual prices of the components is averaged and may vary depending on the economic factors.

We would also recommend that when actually dealing in such a project which deals with practical’s, funds be set aside for those who are to perform such a task, because at some

stage we did not meet certain requirements, due to funding problems or some materials that we required were not available locally in such situation we had to improvise.

5.2 CONCLUSION

While concluding this report we feel quite contended in having completed the project

assignments well on time we had enormous, practical experience on fulfillment of manufacturing schedule of working project model. The credit goes to healthy coordination of our batch collages in bringing out resourceful

fulfillment of our assignments which was prescribed by university. Needless to emphasis here that we had left no stone unturned in our potential effort during machining fabrication and assembly work of project model to our entire satisfaction.

The result of seed extraction/cleaning machine is that the efficiency of machine is considerable higher than that of manual cleaning/extraction method.

124

REFRENCES:

PROPOSED REFRENCE PICTURES THAT AIDED OUR THE DESIGN

Figure 26: Picture showing side view attachment of the rotating mass

Figure 27: Original design of the components prime mover was derived from above

machine

Figure 28: Sketch of the final cleaning section of the seed-cleaner

125

WEB SITES;

[1] MSU News. http://newsbilletin.msu.edu/july27/beal.html (Beal’s Research)

[2] Telewski, F. Department of Plant Biology at Michigan State University.

http://www.plantbiology.msu.edu/telewski.shtml

[3] Telewski, F. “Rip Van Winkle Plants”. http://earthsky.com/2002/esmi021218.html

[4]Material Handling Equipment Dust Collection System Seed Processing Machinery

Horticulture and Garden Tools www.PADSONS INDUSTRIES PVT. LTD.com

[5] Home guides and information communities garden showcase products and sources University

of Florida your Solution for Florida-friendly Gardening ,Gardening in a Minute

[6]Sunflower Power:

http://aginclassroom.org/School%20Gardens/School_Gardening_Lesson_Plans/School_Gard

ening_Lesson_Grade%201%20Garden.htm

[7] National Sunflower Association www.sunflowernsa.com

[8] Thomas Jefferson Agricultural Institute: www.jeffersoninstitute.org/sunflower.php

[9] Ohio State University: http://ohioline.osu.edu/agf- fact/0107.html

[10] Sunflower Project - Nebraska Arboretum:

http://schoolgardens.unl.edu/Sunflower%20Art%20 Curriculum.pdf

[11] Massachusetts Flower Growers’ Association: www.massflowergrowers.com

[12] April 2011, UVM Crops and Soils Team, Contact: [email protected]

[13]http://en.wikipedia.org/wiki/Bending_%28metalworking%29, viewed on 9th October

2015.

[14] http://en.wikipedia.org/wiki/Die_%28manufacturing%29, viewed on 4th January

2015

http://schoolgardens.unl.edu/Sunflower%20Art

mailto:[email protected]

http://en.wikipedia.org/wiki/Die_%28manufacturing%29

126

BOOKS;

[1] Abd El – Tawwab, I. M. ; M. A. Baiomy and S.El-Khawaga.2007.

[2] Design and fabrication of a local rice separating machine. J. Agric.Sci. Mansoura

Univ.,32 (7) :5355-5368.

[3] Awady,M. N.,I. Yehia, M.T. Epaid, and E.M. Arif.2003. Development and theory of

rice cleaner for reduce impurities and loses .Misr. j. Ag.Eng. ,20(4) :53-68.

[4] Institute of Field and Vegetable Crops, Novi Sad, Serbia summary report by Radi

Vujakovic, M., Marjanovic-Jeromela, A., Mrda, J., Miklic, V., Dušanic, N., Balalic, I.

[5] Mechanical and seed cleaning and handling agricultural hand book no. 354 by

Agricultural Research Service United States department of agriculture in cooperation with

Oregon Agricultural Experiment Station

[6] Shigley, J. E., and Mischke, C. R. Mechanical engineering design. (6th ed.). New

York; McGrawHill Companies, Inc., (Chapter-18),2001.

[7] Khurmi, R.S. and Gupta, J.K. ( “Theory of Machines”, Eurasia Publishing house,

New Delhi, India. 2004

[8] Gerald L. “The Application of Fluid Mixers in Edible Oil Processing”. Available

at: www.emimixers.com

[9] Bamgboye, A.I and Adejumo, A.O “Development of a Sunflower Oil Expeller”

Agricultural Engineering International: the CIGR Ejournal, Vol. IX, pp. 1-7,

2007

[10] Agricultural, forestry and fisheries republic of south Africa Obtainable from

Directorate Agricultural Information Services website Private Bag X144 PRETORIA

[11] S.P. Clark, G.W. Baker, P.J. Wan and S.W. Matlock, “Separating Kernels and Hulls

from Oilseed Type Sunflower Seed”, Transactions of the ASABE. 1980

[12] Susanta Kumar Das and R.K. Gupta, “Effects of Impeller Vane Configurations and

Seed Sizeon Dehulling Efficiency of Sunflower Seeds Using a Centrifugal Sheller”,

International Journal of Food Engineering, vol. 1, article 7, issue 3, pp. 1-7, 2005

[13] Susanta Kumar Das and R.K. Gupta, “Fracture Resistance of Sunflower Seed and

Kernel to Compressive Loading”, Journal of Food Engineering, pp. 1-8, 2000.

http://www.emimixers.com/

Date post:	14-Jul-2018
Category:	Documents
Upload:	dangdan
View:	212 times
Download:	0 times

UNIVERSITY ON NAIROBI FACULTY OF …mechanical.uonbi.ac.ke/sites/default/files/cae...iv DEDICATION...

Documents