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FOUNDRY AND FORGING LABORATORY
Subject Code : 10MEL38A / 48 IA Marks : 25
Hours/Week : 03 Exam Hours : 03
Total Hours : 48 Exam Marks : 50
PART – A
Testing of Moulding sand and Core sand
Preparation of sand specimens and conduction of the following tests:
Compression, Shear and Tensile tests on Universal Sand Testing Machine
Permeability test
Core hardness & Mould hardness tests
Sieve Analysis to find Grain Fineness number of Base Sand
Clay content determination in Base Sand
PART – B
2. Foundry Practice
Use of foundry tools and other equipments.
Preparation of moulds using two moulding boxes using patterns or without patterns. (Split pattern, Match plate pattern and Core boxes).
Preparation of one casting (Aluminum or cast iron-Demonstration only)
PART – C
Forging Operations
Calculation of length of the raw material required to do the model
Preparing minimum three forged models involving upsetting, drawing and bending operations
Out of these three models, at least one model is to be prepared by using Power Hammer.
Scheme of Examination
One question is to be set from Part-A : 10 marks
One question is to be set from either Part-B or Part-C : 30 marks
Calculation part in case of forging is made compulsory
Calculation + Forging = 05 +25 = 30 Marks(Forging) Model
Viva-Voce : 10 marks.
Total : 50 Marks
Foundry PracticeFoundry Practice
General Foundry Safety
Before using any equipment or materials, proper knowledge of its usage is required.
PPE protects you from the foundry environment. Wear leather shoes, gloves, and safety glasses with a side shield.
A hat with a brim protects you from spatters.
Use hearing protection in the noisy environment.
When directly working with molten metals, heat, and flame sources, add a hard hat, apron, jacket or cape, leggings, and spats made of leather, aluminized glass fabrics, synthetic fabrics or treated wool.
Foundry furnaces, crucibles, and metals are at such high temperatures, remain cautious while you work.
Do not work with equipment or processes that are unfamiliar to you.
Be conscious of where your hands are when working with conveyors and automated machinery.
General Foundry Safety
Pour and melt in areas that have a nonflammable surface such as metal or sand.
Molten metal that is spilled can travel a great distance, so keep the work area clear.
Have a Class D fire extinguisher handy along with a shovel and clean, dry sand for extinguishing fires.
Melting metals create fumes that can be hazardous to breathe.
Melting scrap metals can create fumes from old paints, lubricants, and coatings and lead, nickel, or chromium additives that are hazardous to breathe.
Use good ventilation through exhaust hoods and wear a respirator that are medically approved, fit-tested, and trained to wear.
Molding sand often contains silica. Silica dust exposure can lead to silicosis, a lung disease, or lung cancer.
Use good ventilation with dust control measures such as non-toxic binding materials to control silica dust.
All equipment you use should operate properly.
Dehydration, heat cramps, heat exhaustion and heat stroke are some of the health effects foundry workers can experience from exposure to excessive heat.
Packing the molds, shaking them out, and cleaning the castings can also be a source of silica dust, so wear a respirator and work in a well-ventilated area.
Inspect foundry equipment on a frequent basis for cracks and signs of wear.
Never introduce water to the furnace or crucible. A trace amount of water can cause a large explosion.
Workers may also develop eye cataracts from infrared and ultraviolet radiation which can be emitted when pouring white hot metal.
General Foundry Safety
The Process of Converting Raw Materials Into Products
Manufacturing ?
It includes
Design of the product
Selection of raw materials and
The sequence of processes through which the product will be manufactured
Introduction
Manufacturing Processes
Casting Machining Forming Joining
(Net shape primary process)
( Subtractive secondary process)(Net shape secondary process)
( Additive secondary process)
Introduction
Foundry: A foundry is a factory that produces metal castings.
Metals are cast into shapes by melting them into a liquid, Pouring the metal in a mold
Removing the mold material or casting after the metal has solidified as it cools.
The most common metals processed are Aluminium and cast iron.
Other metals, such as bronze, steel, magnesium, copper, tin, and zinc, are also used to produce castings.
Introduction
Casting: one of oldest and one of the most popular processes of converting materials into final useful shapes.
It involves a series of operations
Pattern making
Core making
Mould making
Melting
Pouring
Cleaning
Casting is the process of pouring molten metal in to a mould cavity of required shape & size and allowing for cooling
Introduction
Casting
Conventional Methods Unconventional Methods Green sand mould
Dry sand mouldCO2 Moulding (Strong mould)
Permanent (Metal mould)
Shell Moulding (Thin mould)
Investment casting (Precision)
Centrifugal ( without core)
Continuous Casting (Open)
Introduction
Introduction
Casting Terms
Pattern- replica of the part to be cast
Molding material- material that is packed around the pattern to provide the mold cavity
Core- sand or metal shape that is inserted into the mold to create internal features
Flask- rigid frame that holds the molding aggregate
Cope- top half of the pattern
Drag- bottom half of the pattern
Mold cavity - combination of the mold material and cores
Riser - additional void in the mold that provides additional metal to compensate for shrinkage
Gating system - network of channels that delivers the molten metal to the mold
Pouring cup - portion of the gating system that controls the delivery of the metal
Sprue - vertical portion of the gating system
Runners - horizontal portion of the gating system
Parting line - separates the cope and drag
Six Basic Steps of Casting
Pattern making
Core making
Moulding
Melting
Pouring
Cleaning & inspection
Introduction
The Pattern
replica of the part to be cast
Pattern materials:Wood - common material because it is easy to work, but it warps
Metal - more expensive to make, but lasts much longer
Plastic - compromise between wood and metal
Plaster of Paris
Wax –precision casting
Introduction
Types of Patterns(a) solid pattern ( single piece)
(b) split pattern ( Two piece)
(c) match‑plate pattern
(d) cope and drag pattern (e) Sweep pattern
(f) Skeleton pattern
Introduction
Core in Mold
A core consists of two portions: the body of the core and one or more extensions (called prints) Cores are used to create internal cavities. Core is a separate entity placed in a mould to produce a corresponding cavity – hole or undercut – in the casting Cores for sand casting are manufactured by packing specially prepared sand in core boxes Chaplets
Moulding
The cavity in the sand mold is formed by packing sand around a pattern, then separating the mold into two halves and removing the pattern
Major part of Moulding material in sand casting are
1. 85-90% silica sand (SiO2)
2. 3-7% bonding material e.g., clay cereal etc.
3. 3-6% water
Requirements of molding sand are:
(a) Refractoriness
(b) Cohesiveness
(c) Permeability
(d) Collapsibility
Introduction
Moulding sand properties
Porosity or Permeability
It is the property of sand which permits the steam and other gases to pass through the sand mould.
The porosity of sand depends upon its grain size, grain shape, moisture and clay components are the moulding sand. If the sand is too fine, the porosity will be low.
Plasticity
It is that property of sand due to which it flows to all portions of the moulding box or flask.
The sand must have sufficient plasticity to produce a good mould
Adhesiveness
It is that properties of sand due to it adheres or cling to the sides of the moulding box.
Cohesiveness
It is the property of sand due to which the sand grains stick together during ramming. It is defined as the strength of the moulding sand.
Refractoriness
The property which enables it to resist high temperature of the molten metal without breaking down o r fusing.
Classification of Moulding Sand According to their Use
Green sandThe sand in its natural or moist state is called green sand. It is also called tempered sand. It is a mixture of sand with 20 to 30 percent clay, having total amount of water from 6 to 10 percent. The mould prepared with this sand is called green sand mould, which is used for small size casting of ferrous and non-ferrous metals.
Dry SandThe green sand moulds when baked or dried before pouring the molten metal are called dry sand moulds. The sand of this condition is called dry sand. The dry sand moulds have greater strength, rigidity and thermal stability. These moulds used for large and heavy casting.
Loam SandA mixture of 50 percent sand grains and 50 percent clay is called loam sand. It is used for loam moulds of large grey iron casting.
Facing SandA sand which is used before pouring the molten metal, on the surface is called facing sand. It is specially prepared sand from silica sand and clay.
Backing or Floor Sand
A sand used to back up the facing sand and not used next to the pattern is called backing sand. The sand which have been repeatedly used may be employed for this purpose. It is also known as black sand due to its colour.
System Sand
A sand employed in mechanical sand preparation and handling system is called system sand. This sand has high strength, permeability and refractoriness.
Parting Sand
A sand employed on the faces of the pattern before the moulding is called parting sand. The parting sand consists of dried silica sand, sea sand or burnt sand.
Core Sand
The cores are defined as sand bodies used to form the hollow portions or cavities of desired shape and size in the casting. Thus the sand used for making these cores is called core sand. It is sometimes called oil sand. It is the silica sand mixed with linseed oil or any other oil as binder.
Hand tools used in moulding
In hand moulding processes, all the moulding operations, such as ramming the sand, placing and drawing the pattern,
turning over the moulding boxes, etc., are performed by hand
A number of hand tools which are used by the molder to perform above mentioned operations are shown below
Bellow : A bellow is used to blow loose sand particles from the pattern and the mold cavity
Lifter: It lifts dirt or loose sand from the mold. It is used for repairing and finishing the sand mold cavity
Heart & square: It is employed for finishing the mould cavity
Hand rammer: It is used for ramming the sand in molds
Sprue pin: It is tapered wooden rod which is placed in the cope to make Sprue cavity
Hand Riddle: It consists of wire mesh fitted into a circular wooden frame. It is used for cleaning, removing foreign matter from sand.
Trowels: used to finish flat surfaces of the mould, cut in gates, make joints or repair moulds.
Smoothers and corner slics: They are employed to repair and finish corners, edges, round and flat surfaces
Gate cutter: it is a shaped piece of sheet metal . It is used to cut the gate
Shovel : used to transfer moulding sand from store to place of use. Also used to mix and temper the moulding sand
Preparation of Sand MouldPreparation of Sand Mould
Preparation of sand mould
SAND CASTING
Before any casting can take place a wooden pattern is made precisely.
This is called pattern making and in industry this is a very skilful job.
Any inaccuracy at this stage will result in the final cast being wrong or even failing.
Drag is placed inverted on the mould floor and pattern is placed at the center of the box
Preparation of sand mould
Special casting sand will soon be packed around the pattern for easy removal of pattern from parting powder is sprinkled over and around it.
It stops the casting sand sticking to the pattern and pulling away with it when the pattern is finally removed from the sand.
Casting sand is then shaken through a sieve (called riddled sand) so that only fine particles fall around the pattern.
This is called facing sand and it must be fine so that detail on the pattern shows up on the final casting.
Preparation of sand mould
The drag is then packed with more casting sand and then ram it down firmly using a ramming tool.
The tool has two ends, one is cylindrical and is used for general packing down of the sand.
The other end is quite pointed and this can be used for packing sand close up to the pattern.
When the drag is packed fully it is levelled off (called ‘strickled off’) using a straight steel bar.
Preparation of sand mould
The entire drag and its contents are then turned over so that the base of the pattern can be seen
Preparation of sand mould
A top box called a ‘cope’ is then placed on top of the drag and locating pins are put in position so that the casting boxes cannot move sideways
Preparation of sand mould
Sprue pins are positioned.
One usually on the back of the pattern and the other to the side.
These will eventually provide an entrance and exit for the molten aluminium when it
is poured into the sand.
The sand is packed/rammed into the cope in the same way as the drag
Preparation of sand mould
The top box (the cope) is then removed and if all is well the cope with the sand inside should lift off the drag
(bottom box) without the sand falling out.
A small ‘gate’ is cut below the position of one of the Sprue pins.
This will help the molten metal to flow into the cavity left by the mould.
Small tools are available or can easily be made to dig a variety of shapes in the casting sand.
They are similar to small trowels
The pattern is removed using a ‘spike’.
Before removing the pattern it is a good idea to gently tap the spike so that it loosens the pattern from the sand.
It can then be lifted away from the casting box (drag).
Preparation of sand mould
The cope (top casting box) is placed back on top of the drag and the locating pins put in position.
Preparation of sand mould
Vents can be created using a thin piece of welding rod, pushing it through the sand
This allows gases to escape once the molten metal is poured.
Preparation of sand mould
The molten metal is poured with great care.
The molten metal is poured down the hole left by the first Sprue pin (now called the ‘runner’).
As it runs down the runner it flows through the ‘gate’ cut by the trowel, into the cavity left by the pattern and up the riser (the hole left by the second Sprue pin).
The casting should be left for at least an hour before removal from the sand
When removed from the sand, the runner and riser are cut away and the casting is ready for machining
Preparation of sand mould
Sand TestingSand Testing
Sand Testing
Each foundry should draw out a minimum test programme which should be strictly followed for
control of the sand system
Controlling quality of sand in a foundry is very important as the quality of the casting depends on the
quality of the mould sand
The quality of the mould and core depends on the sand, binder, additives used & also on the
percentage of each of the constituents
Sand testing provides clues for improving casting quality
Since molding sands and core sands are important in foundry operations, their control and testing is
essential
Sand control tests are performed on the sand which has been prepared and is ready to be transferred
to the moulding section
Why Sand testing?
Testing of mould & core sand
Sand Testing
Preparation of standard test specimen
Mould hardness test
Core hardness test
Moisture content test on foundry sand
Sieve analysis
Clay content test
Permeability test
Compression, shear & Tensile test
Preparation of standard test specimen
Sand Testing
The standard specimen is prepared using a standard sand rammer and specimen tube accessories.
The specimen is rammed with three blows.
This is the standard procedure.
This operation that is ramming sand three times compacts the sand to a standard hardness
The weight of the ram may be 63-72 N by weight
The ram is dropped from a height of 50mm
Sand Rammer
Sand Rammer
Sand Testing
Mould Hardness Test
Mold surface hardness is the resistance offered by the surface of a green sand mold
An instrument for determining the mold surface hardness shall measure the depth of penetration in to the mold
surface of a plunger having a load applied at a 90º angle to the mold surface
Grain Fineness Test
To Determine the Grain fineness number of the given sand sample
Theory
The base sand is a mixture of grains having a variety of shapes such as round, sub angular, angular, compound
grains.
Base sand is relatively free from any additives/binders
Depending on the average sizes of the grains the sand can be grouped into fine, medium, coarse grains
The shape and size of grains has a large influence on the permeability of sand mix as well as on the bonding action
The shape and size of grains determine the possibility of its applications in various types of foundry practices.
e.g.: fine grains results in good surface finish on the casting but gasses cannot escape out from the mould,
whereas coarse grains sand allows to escape the gasses but the surface finish of the casting will be rough, hence grain
size should be selected appropriately.
Sand Testing
The given size of the sand grain is designated by number called Grain fineness number, that indicates the average
size of the grains in the mixture
The size is determined by passing the sand through sieves having specific apertures which are measured in
microns.
The sieve numbers designates the pore size through which the sand grains may pass through it or retained
Average grain fineness number can be found by the equation FN = Q / P
where Q= (DxC) sum of product of % sand retained in sieves and corresponding multiplier
P = C = sum of % of sand retained in sieves
Sand Testing
Procedure
1.To carry out this test, a sample of dry sand weighing 50 / 100 grams, is placed on the top most sieve number & close the lid.
2.A set of standard testing sieves having standard meshes varying from 1700 till 53 are mounted on a mechanical shaker.
3.The above sample is shaked for about 15 minutes.
4.Weight of the sand retained on each sieve can be obtained.
Sand Testing
Sieve shaker
Observation
Sand used = Base sand; weight of sand = 50gms, time = 10 min
Calculation for grain Fineness number
Sl No Sieve No.(A)
Weight of sand retained (B)
% of sand retained
(C)
Multiplier (D) Product(D x C)
Cumulative of sand retained
123456789
1011
17008506004253002121501067553
PAN
00.21.17.33.1
21.38.05.22.90.30.1
00.42.2
14.66.2
42.616
10.45.80.60.2
5102030405070
100140200300
04
44438248
21301120104081212060
00.42.6
17.223.46682
92.498.298.899
c = 99 = 6016
Results: Grain fineness number of the given sand sample is 60.76
Calculations:
P= c = 99 Q = (CxD) = 6016
Avg GFN = Q / P = 60.76
Clay content Test
To Determine the % of clay present in the base sand
Materials required : Base sand. NaoH solution, Distilled water
Apparatus : Wash bottle, Measuring jar, Mechanical Stirrer & siphon tube
TheoryClay can be defined as those particles having less than 20 microns size.
Moulding sand may contain 2-50% of binding strength and plasticity
Clay consists of 2 ingredients
1. Fine silts
2. True clay.
Fine silt has no bonding power
True clay imparts the necessary binding strength to the moulding sand, thereby the mould doesn’t loose
its shape after ramming.
Clay can also be defined as those particles when mixed with water agitated and then made to settle.
Fails to settle down at the rate of 1/min
The particles of clay are of plate like form & have a very large surface area compared to its thickness and therefore
has very high affinity to absorb moisture
Clay is of mineral origin available in plenty on earth, it is made of alumina silicate.
Types of clay are – Mont Morillonite, kaolinite, & Illite
The first type is referred as Bentonite
ProcedureTake 50gms of base sand in wash bottle, and add 475ml of distilled water, and 25ml of NaoH solution to it
Using mechanical stirrer, stir the mixture for about 3 minutes, and add distilled water to make up the level to 6” height and stir the mixture again for about 2 min. Now allow the contents to settle down.
Siphon out 5” level of unclean water using standard siphon
Add distilled water again up to 6” height and stir the contents again for 10 min. After stirring allow the mixture to settle down for 5min.Siphon out 5” level of water using standard siphon
Repeat the above procedure for 3 times till the water becomes clear in the wash bottle
Transfer the wet sand from the bottle into tray and dry it in an oven at 110c to remove the moisture
Once the sand is dried, weight accurately using weighing instruments and note down the final value & find the clay %.
ObservationBase sand = 50gms
NaoH solution = 25ml
Distilled water = 475ml
Calculations
Weight of the base sand = w1 = 50 gms
Weight of the dry sand = w2 = 49.7 gms
% of clay content in base sand = (w1-w2) / w1 x 100
= (50-49.7) / 50
= 0.6 %
Results The % of clay contained in the given base sand is 0.6 %
To find the effect of water content, clay content on green permeability of sand
Equipment’s required : Permeability meter, balance, Stop watch, Sand rammer, Steel rule, measuring jar, Specimen tube stripper, Specimen tube base
Materials used Base sand, Clay and Water
Theory
Gases and water vapor are released in the mould cavity by the molten metal and sand.
If they do not find opportunity to escape completely through the mould, they will get entrapped and form gas
holes or pores in the casting
The sand must therefore be sufficiently porous to allow the gases and water vapor to escape out.
This property of sand is referred to as permeability.
Permeability Test
Permeability is a physical property of a sand mixture which allows gasses to pass through it easily
The AFS (American Foundry society) definition of permeability is the number obtained by passing 2000cc of air through a standard 2” x 2” specimen under a pressure of 10gm/cm2 for a given time in min.
The permeability number PN can be found out by the equation PN = (VH) / (PAT)
Procedure
Conduct the experiment in two parts.
1.In the first part, vary the water % keeping the clay % constant
2. In the second part vary the clay % and keep the water % constant
In both the cases keep the number of ramming of the specimen as three
Take the weighed proportions of sand and clay & dry mix them together for 3 min.
Then add the required proportions of water and wet mix for another 2 min, to get homogeneous sand mixture.
Take the total weight of the mixture
Fill the sand mixture ( Known weight: e.g. 150g/165g/170g) into the specimen tube and ram thrice using sand rammer.
Use the tolerance limit provided at the top end of the checking the specimen size.
If the top end of the rammer is within the tolerance limits, the correct specimen is obtained.
Now the prepared standard specimen is having a diameter 5.08cm & height 5.08cm
Place the standard specimen along with the tube in the inverted position on the rubber seal.
Operate the valve and start the stop watch simultaneously
When the zero mark on the inverted jar touches the top of water tank, note down the manometer reading, this gives
the pressure of air directly
Note down the time requires to pass 2000cc of air through the specimen. Calculate the permeability number by using
the formula.
PN = (VH) / (PAT) where
V = volume of air passing through the specimen = 2000cc
H = height of the specimen = 5.08cm ( standard value)
P = pressure as read from the manometer in gm/cm2
A = Area of the specimen = πd2/4, where d = 5.08cm ( Standard value)
T = time in min for 2000cc of air passed through the sand specimen
.
Direct scale reading: The permeability can also be determined by making use of graduated marker provided near the manometer.
Steps to be followed:
1.Coincide the graduations on the transparent scale with the miniscus of the manometer
2.Note the reading from the scale
3.This reading represents, the permeability numbers of sand.
Calculations1. Keeping the water constant at 5% & varying the clay
SL No % of sand % of clay % of water Time in seconds
Pressure
Indicated Calculated
1234
92919089
3456
5555
33313231
3.82.63.12.9
239.824373.126303.16334.52
2. Keeping the clay constant at 4% & varying the water
SL No % of sand % of clay % of water Time in seconds
Pressure
Indicated Calculated
1234
92919089
4444
4567
30283233
3.12.83.3
3.35
323.37383.59248.79272.03
Specimen Calculations
The permeability (PN) can be found by the eq PN = (VH) / (PAT)
V = volume = 2000cc
H = height of the specimen = 5.08cm
P = pressure of manometer
A = Area of the specimen = π d2 /4 = 20.27cm2
T = time in min for 2000cc of air passed through sand
PN = (VH)/(PAT) = (2000 x 5.08 x 60)/ (3.8 x 20.27 x 33) = 239.824
Moisture Content Test
To Determine the moisture content in the given sand sample.
Equipments and Materials
Electronic Balance, Oven with temperature 120degree
Theory
In clay bonded sand some moisture is essential to develop working strength.
The influence of moisture may be harmful if the proportion is not controlled within the definite limits.
The strength of a sand is also influenced by its moisture content.
It is therefore important to make certain that the sand contains the correct percentage of water
Procedure
Take the 150 gram sample of the sand.
Mix the water till it becomes in the paste form
Make it in the cylindrical shape.
Weight it
Put the sample in the oven for 10 minutes at 110 degree temperature
Take the sample out of the oven
Weight it again
The difference is the amount of moisture.
Observations
a)Initial weight of the sand sample with water = g
b) Final weight of the sand sample after drying = g
Calculations
The moisture content = Initial weight - Final weight
% Moisture content = (Initial weight - Final weight) / Initial weight
Results
The moisture content is---------------g
Compression Strength Test
To find the green compression strength of the given moulding sand at different % of clay & moisture
Equipments and Materials
Base sand, clay & water, Balance, weighing pan, measuring jar, steel rule, specimen tube with base, stripper, sand ramming machine, compression shackles, Universal sand testing machine
Procedure
Conduct the experiment in two parts:
1. In the first case vary the clay % & keep water % constant. 2. In the second case vary the water % & keep the clay % constant.
Take weighed proportions of sand and clay and dry mix them together in a Muller for 3 min., then add water & wet mix for another 2 min., uniform mixture is obtained
compression shackles
Load LoadTestSpecimen
Fill the sand mixture in to the specimen tube and ram thrice using sand rammer.
Use the tolerance limit provided at the top end of the checking the specimen size, if the top end of the
rammer is within the tolerance limit, the correct specimen is obtained.
Remove the standard specimen using the stripper and place it between the shackles, which are fixed in the
universal sand testing machine.
Rotate the handle to actuate the ram (hydraulic pressure in the cylinder is built up to load the specimen
continuously till the specimen ruptures.
Now note down the compression strength value from the gauge and record the same
Conduct the experiment for the above said two cases and tabulate the results.
SL No % of sand % of clay % of water Compression Strength
gm/cm2 N/mm2
1234
92919089
3456
5555
1.41.62.64.2
0.137340.156960.2543
0.41297
CalculationsKeeping the water constant at 5% & varying the clay
SL No % of sand % of clay % of water Compression Strength
gm/cm2 N/mm2
1234
92919089
4444
4567
2.63.42.22.4
0.255060.33350.21580.2354
Keeping the clay constant 4% & varying water
Calculations(1.4 x 9.81) / 10 x 10 = 0.13734 N /mm2
Shear Strength Test
To find the green shear strength of the given moulding sand at different % of clay & moisture
Equipments and Materials
Base sand, clay & water, Balance, weighing pan, measuring jar, steel rule, specimen tube with base, stripper, sand ramming machine, shear shackles, Universal sand testing machine
Load
Load
TestSpecimen
shear shacklesTheory
Shear strength is the ability of sand particles to resist the shear stress & stick together
Insufficient strength may lead to collapse of the sand in the mould or its partial destruction during handling the mould & core may also be damaged during the flow of molten metal in the mould cavity
The molding sand must possess sufficient strength to permit the mould to be formed to the desired shape & retain the shape even after the molten metal poured in to the mould
In shearing the rupture occurs parallel to the axis of the specimen
Procedure
Conduct the experiment in two parts
1. In the first case vary the clay % & keep water % constant.2. In the second case vary the water % & keep the clay % constant
Take 200gms of foundry sand ( mixture of sand, clay & water as specified)
Prepare the standard sample using these mixture as specified in procedure
Transfer the sand mixture into the tube & ram it thrice in the sand rammer to get the standard specimen. The top of the rammer rod should lie with in the tolerance limits.
Fix the shearing shackles to the universal sand testing machine
Remove the standard specimen from the tube using a stripper & load it on to the universal testing machine
Apply the hydraulic pressure by turning the handle of the testing machine continuously until the specimen ruptures.
Take the readings from the meter directly showing a shear strength of the specimen.
Calculations Keeping the water constant at 5% & varying the clay
SL No % of sand % of clay % of water Shear Strength
gm/cm2 N/mm2
1234
92919089
3456
5555
0.350.70.80.6
0.03430.06860.07840.0588
Keeping the water constant at 5% & varying the clay
SL No % of sand % of clay % of water Shear Strength
gm/cm2 N/mm2
1234
92919089
4444
4567
0.30.40.50.6
0.02940.03920.04900.0588
Bending Test
To find the green bending strength of the core sand using different types of binders; core oil binder &
sodium silicate binders
Equipments and Materials
Base sand (silica sand), core oil, sodium silicate
Theory
A core is a compacted sand mass of a known shape
When a hollow casting or a complex control is required (to have a hole or internal shape through or blind depth) a core is used in the mould or a mould is created out of core
Core boxes are used for making cores. They are either made by a single or in two parts their classification is generally according to the shape of the core or the method of moving the core.
Split core box is very widely used and is made in two parts, which can be joined together by means of
dowels, to form a complete cavity for making the core
The purpose of adding the binder to the molding sand is to impart the strength & cohesiveness to the sand
to enable to retain its shape after core has been rammed.
Binders can be (a) organic binders – dextrine core oil (b) inorganic binders – sodium silicate, Bentonite
Procedure
Conduct the experiment in two parts
1. using the core oil as a binder2. using sodium silicate as binder or any other binders
Make proper proportions of core sand & binder then mix together thoroughly
Assemble the core box and fill the sand & ram on to it
Place the core box under sand rammer & ram the sand thrice
Using a wooden piece top the core box gently from the sides. Remove the core box so that rammed core remains on a flat metal plate
Bake the specimen (which is on plate) for about 30 min at a temperature of 150-200c in an oven
Fix the bending shackles on to the sand testing machine then place the hardened specimen between the shackles
Apply the load gradually by turning the hand wheel of the testing machine. Note down the readings when the specimen breaks
Repeat the procedure for different % of binder & tabulate the readings
SL No % of sand % of Dextrine % of water Bending Strength
kg/cm2 N/mm2
1234
9493.593
92.5
11.52
2.5
5555
0.30.6
0.850.9
0.29430.58860.83380.8829
Observation
Bending strength of sand Varying content of organic binder ( Dextrine) water content 5%
Bending strength of sand Varying content of Inorganic binder ( Sodium silicate) & no water
SL No % of sand % of Sodium Silicate Bending Strength
kg/cm2 N/mm2
1234
97969594
3456
4.54
3.53
4.41453.9243.4332.943
Calculations
Bending strength = reading x 9.81 in kg/cm2= reading x 10/100 x 9.81 in N/mm2
= (4.5 x 10 x 9.81) / 100 = 4.41 N/mm2
Tensile Test
To determine the tensile strength of core sand using different types of binders, core oil binder & sodium silicate binders, etc.
Equipments and Materials
Base sand (silica sand), core oil, sodium silicate, Split core box, sand rammer, oven, tensile shackles, Universal sand testing machine
Procedure
Conduct the experiment in two parts
1. using the core oil as a binder2. using sodium silicate as binder or any other binders
Take proper proportions of core sand & binder then mix together thoroughly
Assemble the core box and fill the sand mixture into it
If the binder is sodium silicate, pass co2 gas for 5 seconds. The core hardens instantly & the core can be directly used
Fix the tensile shackles on to the sand testing machine and place the hardened specimen in the shackles
Apply the load gradually by turning the hand wheel of the testing machine. Note down the reading, when the specimen breaks
Repeat the procedure for different % of binder & tabulate the readings
Place the core box under sand rammer & ram the sand thrice
Using a wooden piece top the core box gently from the sides. Remove the core box so that rammed core remains on a flat metal plate
Bake the specimen (which is on plate) for about 30 min at a temperature of 150-200c in an oven
Observation
1. Water 5% constant for varying content of Dextrine binder (organic binder)
SLNo % of sand % of Dextrine % of water Tensile Strength
kg/cm2 N/mm2
1234
9493.593
92.5
11.52
2.5 5
1.62.63.23.4
1.56962.55063.13923.3354
2. No Water used for varying content of sodium silicate binder (Inorganic binder)
SLNo % of sand % of sodium silicate
Tensile Strength
kg/cm2 N/mm2
1234
9493.593
92.5
3456
1.72.6
1.752.9
1.66772.55061.7162.844
CalculationsTensile strength = Direct reading kg/cm2 x 9.81
= (reading x 10 x 9.81) / 100 N/mm2
Forging PracticeForging Practice
Outline
Introduction
Forging – Basic Principles
Forging – Terminology
Objectives of the forging lab
Forging – materials and equipment
IntroductionIntroduction
A metal is shaped by compressive forces
Oldest metal working process – 4000BC
Can be performed with a hammer and anvil
Typical forged products
Bolts
Rivets
Connecting rods
Forging is a Bulk Deformation Process in which the work is compressed between two dies.
According to the degree to which the flow of the metal is constrained by the dies.
IntroductionIntroduction
FORGING TERMINOLOGIES
Hot forging
Plastically deforming an alloy at a temperature above its re-crystallization point
Open Die Forgings / Hand Forgings Made with repeated blows in an open die
The operator manipulates the work piece in the die.
Impression Die Forgings / Precision Forgings:
Are further refinements of the blocker forgings.
The finished part more closely resembles the die impression.
Cold working is metal forming performed at room temperature.
Advantages: better accuracy, better surface finish, high strength and hardness of the part, no heating is required.
Disadvantages: higher forces and power, limitations to the amount of forming, some material are not capable of cold working.
Warm working is metal forming at temperatures above the room temperature but below the recrystallization temperature.
Advantages: lower forces and power, more complex part shapes, no annealing is required.
Disadvantages: some investment in furnaces is needed.
Hot working involves deformation of preheated material at temperatures above the re crystallization temperature.
Advantages: big amount of forming is possible, lower forces and power are required, forming of materials with low ductility, no work hardening and therefore, no additional annealing is required.
Disadvantages: lower accuracy and surface finish, higher production cost, and shorter tool life.
IntroductionIntroduction
Illustration of Simple forging Operation
Anvil
serves as a work bench to the blacksmith, where the metal to be beaten is placed.
made of cast or wrought iron with a tool steel face welded on
The flat top has two holes; the wider is called the hardy hole, where the square shank of the hardy fits.
The smaller hole is called the punch hole, used as clearance when punching holes in hot metal
ADVANTAGES AND DISADVANTAGES OF FORGING
DISADVANTAGES
High tool cost.
High tool maintenance.
Limitation in size and shape.
ADVANTAGES
Uniformity of qualities for parts subject to high stress
and loads.
No weight loss.
Close tolerance.
Less machining or no machining in some cases.
Smooth surface.
High speed of production.
Incorporation in welded structures, i.e., what can be
welded easily.
Forging OperationsForging Operations
Upsetting forging
Upset forging increases the diameter of the work piece by compressing its length.
A few examples of common parts produced using the upset forging process are engine valves, couplings, bolts, screws, and other fasteners.
Bending Operations
Bending is very common forging operation. It is an operation to give a turn to metal rod or plate. This is required for those which have bends shapes.
Drawing
This is the operation in which metal gets elongated with a reduction in the cross sedation area. For this, a force is to be applied in a direction perpendicular to the length axis.
Fullering
It a similar to material cross-section is decreased and length increased.
To do this; the bottom fuller is kept in angle hole with the heated stock over the fuller .
The top fuller is then kept above the stock and then with the sledge hammer, and the force is applied on the top fuller.
Edging
It is a process in which the metal piece is displaced to the desired shape by striking between two dies
Edging is frequently as primary drop forging operation.
Punching
It is a process of producing holes in motel plate is placed over the hollow cylindrical die.
By pressing the punch over the plate the hole is made.