BALAJI INSTITUTE OF TECHNOLOGY AND SCIENCES MANUAL NEW_2 year 2sem.pdfAdjust the guide rod nuts to...

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BALAJI INSTITUTE OF TECHONOLOGY & SCIENCES

BALAJI INSTITUTE OF TECHNOLOGY AND SCIENCES

NARSAMPET WARANGAL

MECHANICAL DEPARTMENT

PRODUCTION TECHNOLOGY LAB MANUAL

Prepared by

T.S.R.BABU

Asst Prof

BALAJI INSTITUTE OF TECHNOLOGY AND SCIENCES

NARSAMPET WARANGAL

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LIST OF EXPERIMENTS

1. INJECTION MOULDING

2. BLOW MOULDING PROCESS

3. BRAZING

4. BENDING PROCESS

5. PREPARATION OF LAP JOINT USING SPOT WELDING

6. PREPARATION OF LAP JOINT USING ARC WELDING

7. PREPARATION OF BUTT JOINT USING ARC WELDING

8. MELTING PRACTISE

9. PREPARATION OF MOULD CAVITY USING SPLIT PATTERN

10. PREPARATION OF MOULD CAVITY USING SINGLE PIECE

PATTERN

11. SAND PREPARATION AND STRENGTH & COMPRESSION

TESTING

12 .PATTERN MAKING

13 .PLASMA ARC WELDING

14. CORE MAKING

(a) TENSILE CORE BOX

(b) TRANSVERSE CORE BOX

15. SAND TESTING

16. TENSILE STRENGTH

17. PERMEABILITY TEST

18. Sand Rammer

19. HYDRAULIC PRESS

20. FLY PRESS

21. TUNGSTEN INERT GAS (TIG) WELDING

22. STUDY OF PROGRESSIVE DIE

12.

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INJECTION MOULDING

Aim: To Prepare a Plastic product using Injection Moulding machine

Equipment: Injection moulding machine.

Material Required: High grade poly ethylene

Description of The Equipment: Hydraulic Plastic Injection Moulding machine, Model JIM-

1HD has been designed for moulding variety components up to 45 Gms capacity in polystyrene.

The machine is robustly built to ensure consistent high quality and volume production of

precision components. Operator fatigue due to injection process is completely eliminated by use

of hydraulic power for both the injection and releases operations.

Locking Unit: This locking made by Hydraulic Cylinder.

Injection Unit: Injection Unit consists of two guide rods, nuts, top and bottom plates with

injection cylinder and barrel. Injection cylinder is designed to develop 3 Tons load. Barrel

diameter 30mm is attached with the machine as standard.

Hydraulics: Hydraulic pump is driven by 3 HP Induction motor for a rated delivery of 14 lp, at

1440 Rpm and at 80kg/cm2. The maximum pressure in the hydraulic system is present in our

works and is not to be altered. The oil tank capacity is 60 liters. All hydraulic system

manufacturers’ safety precautions are provided to hydraulic system by using section strainer,

which will prevent the contamination entering into the system.

Oil Cooler: Oil cooler provided to keep the oil temperatures below 500c which will gives more

life to hydraulic oil in continuous use.

Electricals: Electrical control panel with automatic blind temperature controller is fixed on the

right hand side of the machine for clear viewing of the temperature and for easy to operate the

switches. Designed with safety measure, which will protect the motor from over load.

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Working Procedure: Injection moulding makes use of heat softening characteristics of thermo

plastic materials. These materials soften when heated and re harden when cooled. No chemical

change takes place when the material is heated or cool. For this reason the softening and re

hardening cycle can be repeated any no. of times.

1. The granular moulding material is loaded hopper where it is metered out in a heating cylinder

by a feeding device.

2. The exact amount of material is delivered to a cylinder, which is required to fill the mould

completely.

3. Set the die in position Provide spacing plates if necessary. Clamping the Die using hydraulic

operate ram.

4. Set the injection pressure by rotating (clockwise) the regulator knob to suit the requirement of

moulding the container.

5. Switch on the heater. Set the required timings to the timers, for top and middle Heater. Set the

temperature by adjusting automatic temperature controller to control the bottom heater. Allow

sufficient time to stabilizer. When temperature reached, operate the hand lever valve to inject the

material.

6. Apply injection pressure on the heated material using plunger rod.

7. The injection ram pushes the material in to the heating cylinder and in doing so pushes a

small amount of heated material out of the other end of the cylinder through the nozzle and

screw bushing and into the cavity of closed mould.

8. The material is cooled in a rigid state in the mould.

9. Release the injection pressure. In clamp the Die using hydraulic operated ram.

10. The mould is then opened and piece I ejected out.

Result: Required product is made using injection moulding process.

VIVA QUESTIONS: 1. What are the properties of thermo plastics & thermosetting plastics?

2. How plastics are classified?

3. What are the applications &limitations of thermosetting plastics?

4. What are the applications &limitations of thermo plastics?

5. How thermo plastics &thermo setting plastics are produced?

6. Describe the process of blow moulding?

7. Describe the process of injection moulding?

8. How thermo plastics differ from thermo setting plastics? 9.Explain the following i) polyester.

ii)thermoplastics. iii)thermo setting plastics

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BLOW MOULDING PROCESS

Aim: To prepare a bottle of 200ml using blow moulding machine.

Equipment: Blow moulding machine

Material Required: Low grade poly ethylene

Working Principle: The process is applied to only thermo plastics, which are used for

producing hollow objects such as bottle, and flow table objects by applying air pressure to the

sheet material when it is in heated and in soft pliable condition. Blow moulding can be

accomplished in two manners; one is direct blow moulding and other indirect blow moulding. In

the former case, a measured amount of material in the form of tube is either injected or extruded

in a split cavity die. The split mould is closed around the tube, sealing off the lower end. The air

under pressure is blown into the tube, which causes the tube to expand to the walls of cavity. In

the latter case, a uniformly softened sheet material by heat is clamped at the edges between the

die and cover, which causes the sheet to attain a hemispherical shape or the configuration of

mould whatever it may be parts obtained by indirect blow moulding have excellent appearance

but they are more costly as only to percent of the sheet stock is utilized and also there is a

tendency for excessive thinning of sheet at the deepest point

. Experimental Diagram:

Operating instructions: 1. Install the machine on a leveled strong flooring near the compressor

(within 2 meters). For letter rigidity foundation bolt is recommended & anti vibration rubber

mounting can be used.

2. The machine must be placed in a position where all parts are accessible readily.

3. Check for loose any loose electrical connection with the help of certified electrician and with

the electrical circuit enclosed. 47

4. Fill the lubricator with SAE 20 grade oil to the level indicated. The lubrication has been set to

allow one drop of oil for every 5 strokes of air cylinder (oil) drop is factory set, no need to

adjust)

5. Connect the air filter to the compressor by rubber/nylon hose (Min inside dia 10mm), pressure

with standing capacity 20kg/cm2.

6.Set the pressure switch in the compressor as per the compressor manual to switch on 7 kg/cm2

pressure & switch off at 10kg/cm2 (NOTE: The air pressure should not exceed 10cm2)

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7. Set the air pressure in machine by adjusting the injection & release regulator (18)

. 8. Set release pressure 2kg/cm2 by adjusting release regulator.

9.Operate the hand lever valve (13) and check for smooth functioning of plunger.

10.Set the blow pressure in regulator (15) and operate the hand lever valve (14) to check flow of

air throw blow nozzle.

11.Electrical connection should be given as indicated on the main plug phase, neutral and earth.

12.Proper earthing should be done.

13.Check the incoming voltage (230VAC, 50Hz) Now the machine is ready for operation.

PROCEDURE: 1. Set the die in position. Adjust the guide rod nuts to suit die height. Align the

tapered face of the die for sealing the parison while blowing also checks for the face opening and

closing of the die.

2.Ensure minimum die height is 80mm. provide spacing plates if necessary.

3. Set the injection, release and blow pressure by rotating (clockwise) the regulator knob to suit

the requirement of moulding the container.

4. Feed correct quantity & quality of plastic material and switch on the power supply.

5. Switch on the heater.

6. Set the required timings controller to control the bottom heater.

7. Allow sufficient time to stabilizer.

8. When temperature reached, operate the hand lever valve.

9. Extrude the parison (Tubular form) to the required length and close the two die halves.

Release the injection cylinder.

10. Operate the hand lever valve and blow the air so that the parison to form the shape of the

container as designed in the die.

11. Allow the component to cool.

12.Open the die & take the product out of the die.

13. Now the machine is ready for nest cycle.

RESULT: Required product is made using blow molding process

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VIVA QUESTIONS

1. Following material is a good example for thermo-plastics (A )

2. Thermo-plastics are having (D)

3. Injection moulding is the ideal method of processing [B ]

4 Process used to production hollow products by inflation of tube or parison, is [ B]

5. Injection moulding pressures usually range from _______ [D ]

6. Blow moulding Process used for producing _____ types of Parts. [ B]

7. The _________ additive increases strength, stiffness and impact resistance to the plastics.

8. PVC stands for ___________.

9. Injection moulding is similar to ___________ casting

10. _________ plastics are the plastics that cannot be melted once they are solidified.

11. Thermoplastic materials are produced by ____________ process 12. Plastics are bad

conductor of ___ and _______

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BRAZING

Aim: To join two pipes or sheets by brazing process.

Equipment And Material Required: Oxy-acetylene torch, Flux, filler rod, GI sheets

150x150x1mm

Tools Required: Wire brush, Hand gloves, Chipping hammer, Spark lighter

Description: Brazing is coalescence of a joint with the help of a filler metal whose melting

temperature is 4500C and is below solidify temperature of the base metal. The filler metal is

drawn into the joint by means of capillary action. Brazing is a metal-joining process whereby a

filler metal is heated above melting point and distributed between two or more close-fitting parts

by capillary action. The filler metal is brought slightly above its melting (liquidus) temperature

while protected by a suitable atmosphere, usually a flux. It then flows over the base metal

(known as wetting) and is then cooled to join the workpieces together. It is similar to soldering,

except the temperatures used to melt the filler metal are higher.

Brazing joints:

BOLTS:

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Pipes:

Procedure: 1. The surface to be joined is cleaned properly.

2. Sheets are joined and laid by giving proper clearance.

3. Flux is applied to the joint.

4. Joint is to be heated by using welding torch to heat the filler metal to its melting temperature

when the filler material is placed at the joint.

5. The filler material is flown into the service by capillary action and joint is made.

Precautions: 1. As the filler metal fills the joint by capillary action, give only needed clearance.

2. See that the joints are extremely clean.

Result: Two sheets are joined using brazing process

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BENDING PROCESS

Aim: To study and analyze the significant effect of spring back on bending and other sheet metal

forming process and to know how to determine the spring back factors for materials.

Requirement: Different bending samples of Brass, Steel, Galvanized Iron and Aluminum are

required. Tubes- Dia 6mm Steel Rule Scriber Snips Blender

Equipment: Bench Wise Bending Dies

Theory:

Bending and bending dies: Bending is the metal working process by which a straight length is

transformed into a curved length. It is very common forming process, for changing sheet and

plate into channels, drums and tanks etc. During the bending operation, the outer surface of the

material is in tension and the inside surface is in compression. The strain in the bent material

increases with decreasing the radius of curvature. The stretching of the bend causes the neutral

axis to move toward the inner surface. In most cases, the distance of the neutral axis from the

inside of the bend is 0.3 t to 0.5 t , where “t” is thickness of the part.

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Bending Methods: The two bending methods commonly used are v-bending and edge bending.

1. V- Bending: In v-bending , a wedge shaped punch forces the metal sheet or strip into a wedge

shaped die cavity, shown in fig. The bend angle may be acute 90°, or obtuse. As the punch

descends , the contact forces at the die corner produce a sufficiently large bending moment at the

punch corner to cause the necessary deformation. To maintain the deformation to be plane strain,

the side creep of the part during its bending is prevented or reduced by incorporating a spring

loaded knurled pin in the die.

2.Edge Bending: In edge bending , a flat punch forces the stock against the vertical force of the

die. The bend axis is parallel to the edge of the die and the stock, is subjected.

Minimum Bending Radius When Bending Bars of Steel:

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There is not a mathematical formula for determining the minimum bending radius of steel

sections. To better explain this, lets look at bar bending. Steel is curved using a cold-roll bending

process. Steel sections are put into a section bender (also called an “angle roll”) with a three or

four roll configuration. Rollers put force against the feed path to force the metal stock into a

predetermined curved path. There is force applied by the rolling machine (stress) which in turn

changes the structural steel into a curved shape (strain). If you look at the diagram below, steel is

very ductile, and after a very brief elastic state the material goes into plastic deformation. The

goal is to reach the desired radius without reaching the necking or ultimately the fracture point.

Looking back at the diagram above, the goal is to maximize the elongation limit in the bar

bending process which is done by going with steel that is more ductile. A case study was done

recently on bending 2.25 inch diameter round bar to a 3 inch inside radius. Two different

material grades were used. The first was AISI 1144 which does not have a lot of ductility. The

reason for this is 1144 is a free-machining material that has sulfur added to it to make it more

brittle. It is made this way so when the cutting tool hits the sulfide inclusions, the material chips

away easier. When bending 1144 to a 3 inch inside radius, the material was not able to withstand

the stress and fractured. The second material type was Alloy 4140 HR which has a typical

elongation of 25% vs. 1144 which has a typical elongation of only 10%. The 3 inch inside radius

was successful without fracture using 4140. This case study better explains that the minimum

radius is not the same for different material grades.

Procedure: 1) Set the bending die on the pressing machine.

2) Set up the pressing machine for the test. 3) Select a sample test, and then measure its thickness

(t). 4) Measure the die angle (αi ) and die radius (Ri). 5) Perform the bending process by putting

the flat sheet on the lower half of the bending die and then press the sheet to the required bending

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shape by the upper half of the bending die. 6) Measure the final sheet angle (αf ) and radius (Rf).

After bending. 7) Record all the measurements and observations. 8) Repeat the test for different

sheet thick nesses and materials.

Precautions:

Working with sheet metal, especially after it‟s been cut, can be dangerous. Each cut you

make exposes sharp edges and creates burrs that can slice a finger. That‟s why it‟s vital

that you take safety precautions. Wear safety gloves whenever possible, and always wear

safety goggles and work boots. Never run your hands, even when gloved, over a cut edge.

Always file down burrs promptly. Keep your work surface free of scrap. Metal waste also

has hazardous edges. Handle metal sheets with care, especially if they are wet, because

moisture mixed with oil and dirt can slick the surface and make it hard to grasp. Finally,

make sure your hammers are solid and your shears are sharp.

Results: To studied and analyzed the significant effect of spring back on bending and

other sheet metal forming process to determined the spring back factors for materials

BENDING

1. Explain hot working and cold working processes.

2. Differentiate the properties of hot worked and cold worked products.

3. Write about the theory of rolling.

4. Write about forces in rolling and power requirements.

5. Describe the processes of Blanking and Piercing.

6. Describe bending and forming operations.

7. Describe wire drawing process with neat figure.

8. Describe tube drawing.

9. Describe coining, hot spinning and cold spinning processes.

10. What are the types of presses?

11. In cold working of metals, the working temperature is

12. Which mechanical property of a metal should posses to enable it to be mechanically

13. Cold working of metal increases

14.The increase in hardness due to cold working, is called

15. The process which takes place below recrystallization temperature is known as

16. The recrystallization temperature of steel is

17. Mechanical working of metals is the shaping of metals. This is carried by

18.. Rolling is normally hot working processes.

19.. The ductility property of metalsin hot working processes ----------

20. Cold working process can be applied on the components having diameter up to---------

21. Mechanical properties of the metal improve in hot working due to -------------

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22. Process of increasing the cross-section ofa bar and reducing its length is known as ----------

23. In hot working surface finish is -----

24. Cold or hot rolling does not produce a ------------ section.

25.. Ring rolling is used to --------------

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PREPARATION OF LAP JOINT USING SPOT WELDING

Aim: To study the effect of the current on weld strength-using spot welding process

Equipment: Spot welding machine

Material Required: Two metal pieces of size 4”x2”

Description of The Equipment:

A typical resistance spot welding machine essentially consists of two electrodes, out of which

one is fixed. The other electrode is fixed to a rocker arm (to provide mechanical advantage) for

transmitting mechanical force from a pneumatic cylinder. This is simplest type of arrangement.

The other possibility is that of a pneumatic or hydraulic cylinder being directly connected to the

electrode without any rocker arm. For welding large assemblies such as car bodies, portable spot

welding machines are used. Here the electrode holder and the pneumatic pressurizing system is

present in the form of a portable assembly which is taken to the place, where the spot is to be

made. The electric current, compressed air and the cooling water needed for the electrodes is

supplied through cable and hoses from the main welding machine to the portabe unit.

In spot welding, a satisfactory weld is obtained when a proper current density (A/Sq mm) is

maintained. The current density depends on the contact area between the electrode and the work

piece. With the continuous use, if the tip becomes upset and the contact area increases, the

current density will be lowered and consequently the weld is obtained over a large area. This

would not but able to melt the metal and hence there would be no proper fusion. A resistance-

welding schedule is the sequence of events that normally take place in each of the welds. The

events are the squeeze time is the time required for the electrodes to align and clamp the two

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work pieces together under them and provides the necessary electrical contact. The weld time is

the time of the current flow through the work pieces till they are heated to the melting

temperature. The hold time is the time when the pressure is to be maintained on the molten metal

without the electric current. During this time, the pieces are to be forge welded. The off time is

time during which, the pressure on the electrode is taken off so that the plates can be positioned

for the next spot. The off time is not normally specified for simple spot welding, but only when a

series of spots are to be made in a predetermined pitch.

THEORY: Resistance welding: the category resistance welding (RW) covers a number of

processes in which the heat required for welding is produced by means of electrical resistance

across the two components to be joined. These processes have major advantages, such as not

requiring consumable electrodes, shielding gases, or flux. The heat generated in resistance

welding is given by the general expression

H = I2 RT,

Where H = heat generated (in joules (watt-seconds)) I = current (in amperes), R= resistance (in

ohms), and T= time of current flow (in seconds) The actual temperature rise at the joint depends

on the specific heat and on the thermal conductivity of the metals to be joined. The tips of two

opposing solid cylindrical electrodes touch a lap joint of two sheet metals, and resistance heating

produces a spot weld. In order to obtain a strong bond in the weld nugget, pressure is applied

until the current is turned off. Accurate control and timing of the electric current and of the

pressure are essential in resistance welding. The strength of the bond depends on surface

roughness and on the cleanness of the mating surface. Oil, paint, and thick oxide layers should,

therefore, be removed before welding. The presence of uniform, thin layers of oxide and of other

contaminants is not critical. The weld nugget is generally 6 to 10 mm in diameter. The surface of

the weld spot has a slightly discolored indentation. Currents range from 3000 A to 40000 A: the

level depends on the materials being welded and on their thicknesses.

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PROCEDURE:

1. Switch on the machine and set the current in the machine to 2 Ampere

2. Set the timer to two seconds

3. Overlap the two metal pieces to the requires size and place them between the two electrodes.

4. Apply pressure by foot on the lever such that two electrodes come into contact if the over

lapped metals.

5. After 2 seconds remove the pressure on the lever slowly.

6. Now the joint is ready for use.

7. Repeat the same procedure at various amperes

8. Test the strength of the joints using universal testing machine

PRECAUTIONS: 1. Ensure that the electrodes should not be touched.

2. Don’t touch the welded potion by hand immediately after the welding is done.

RESULT: Effect of current on strength of spot weld is studied

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VIVA QUESTIONS: 1. Weld spatter is a

2. Seam welding is

3. In D.C straight polarity.

4. In thermit welding, the Iron oxide and aluminium oxide are mixed in the proportion of

5. Flux is not used in welding 6.Projection welding is a

7. In soldering, the melting point of the filler metal should be

8. Seam welding is

9. Preheating is essential in welding of _______ material

10. Oxy –acetylene flame cuts metal by its

11. For cutting operation,………… ………….flame is used

12. Oxygen to acetylene ratio in case of natural flame is__________

13. In resistance welding ______ _______ is low and ___________ is high.

14. Upto what thickness of plate, edge preparation for welding is not required __________

15. In resistance welding the electrode material is made of ______Copper________.

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PREPARATION OF LAP JOINT USING ARC WELDING

AIM: To prepare Joints for welding suitable for lap welding.

TOOL REQUIRED: Scale, Scriber, Hand hack saw, Flat file, Swing scale protector, welding

machine, Shield, gloves, Wire brush, Chipping hammer, Welding rod

MATERIAL REQUIRED: Mild steel plate of 5 mm thickness.

PROCEDURE FOR LAP JOINT: 1. Two pieces are cut to size and surfaces to be welded are

cleaned properly.

2. Electrode is held in electrode holder and earth clamp is clamped to be work piece.

3. The pieces are positioned overlapping each other for lap joint and tack weld is done at two

end points.

4. 2-3 mm spark gap is maintained and welding is done smoothly.

5. Slag is removed using chipping hammer and weld is cleaned using wire brush.

PRECAUTIONS: 1. Wear apron, shoes, nose mask, gloves and tight fitted clothes. Be careful and attentive while

working on welding job.

2. During welding don‟t see the welding light rage directly without the gaggle face shield.

3. Do not cool the welding piece in water.

4. Do not keep electrode holder on the welding machine.

5. No inflammable material should be present in welding shop.

RESULT: To prepared Joints for welding suitable for lap welding

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VIVA QUESTIONS: WELDING-1

1. What are the basic requirements of welding?

2. What is ARC welding. Explain in detail.

3. Explain the classification of welding processes.

4. What are the different types of welded joints?

5. Write about design of welded joints.

6. What is ARC blow in arc welding?

7. What are the gases used in gas welding?

8. Write about forge welding and its application.

9. Write about resistance welding and its application.

10. What is thermit welding? Explain its applications.

11. what is the phenomina of weld decay occurs in

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PREPARATION OF BUTT JOINT USING ARC WELDING

AIM: To prepare Joints for welding suitable for butt- welding and lap welding.

TOOL & EQUIPMENT REQUIRED:

Scale, Scriber, Hand hack saw, Flat file, Swing scale protector, Welding machine, Shield, gloves,

Wire brush, Chipping hammer, Welding rod.

MATERIAL REQUIRED: Mild steel plate of 5 mm thickness

Procedure:

1. Given 2 M.S. plates are filled at an angle of 450 at 2 surfaces to be joined (V groove is

formed)

2. Electrode is fixed to electrode holder.

3. Connections to be given such that electrode- negative and work piece positive.

4. Welding is to be done carefully for the half-length of the plates.

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5. The work piece is to be cut into two halves by power hacksaw.

6. The beads are polished, etched with two percent natal solution and studied under the

microscope whose magnification factors 10X for the heat effected zone.

7. By gripping the beads b/w the jaws pf Tensile testing machine and load is applied until the

work piece breaks and the readings is to be noted.

8. The same procedure is repeated for the remaining half which is welded by reverse polarity

and the results are to be compared.

Result : To prepared Joints for welding suitable for butt- welding by using of various tools and

equipments

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MELTING PRACTICE

Aim: To observe the melting of metals to prepare the casting.

Material Required And Apparatus: Oil furnace, Ladle to sir, Metal.

Specifications: Capacity – 3 kgs. Crucible – Graphite of Dia 1 „ x height 1.5‟‟ Burner – O

Number Blower – 1 HP 2880 rpm. Coal-5Kgs Insulation – Fire bricks Outer Casting – Mild steel

duly painted.

Melting Procedure For Aluminum Alloys:- The charge materials, chemicals should be free

from moisture, oil, and corrosion powder and should be preheated before charging. The

calculation of charge should be done considering the melting loss of each element in the melting

furnace for final desired analysis.

1. The furnace crucible should be clean and red hot for charging

2. Aluminium alloys get readily oxidized and form dross, using proper covering top with flux

and chemicals help to reduce this. Different proprietary chemicals are available for different

alloys.

3. Melting should be done under steady conditions without agitation. Stirring is done to reduce

gas pickup.

4. Once melting is complete, degassing using solid chemicals like hexachloro-ethane which

evolves chlorine by purging with nitrogen or argon gas is done to remove the dissolved

hydrogen. Hydrogen is evolved from moisture.

3H2O+2Al→Al2O3+6H

Hydrogen absorbed by liquid metal causes serious porosity in casting during solidification.

Degassing should be done in the temperature range 7300 C to 7500 C

5. Liquid metal after degassing is treated with sodium containing chemicals to improve

mechanical properties.

6. Liquid metal once ready should not be super heated. Agitated or kept long in the furnace

which will cause dressing and gas pickup. Dross should be skimmed properly before pouring.

7. Alloys containing magnesium should be melting carefully as it is highly reacting. Special

fluxes and chemicals like sulphur are used to inhibit the reactivity and prevent spontaneous

ignition, melting loss and dross.

Casting Defects Due To Improper Melting:

Improper chemical analysis: Incorrect charge, calculations, including wrong estimates of

melting losses, metal recovery, excessive losses due to improper fluxing and slogging operations,

improper covering of non-

Ferrous melt causes this defect.

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2. Gassy metal/hydrogen pickup/pinhole porosity: unclean melting causes formation and

absorption of hydrogen into liquid metal. As casting solidifies, the absorbed hydrogen losses

solubility and forms cavities inside casting.

3. Oxygen absorption Excessive oxygen furnace operations in atmosphere following oxidation

during melting cause this defect. It also causes loss of costly metal added in the charge.

4. Slag inclusions Improper fluxing and slag removal slag particles to be mixed in the metal

being poured. Careless pouring, lip pouring for alloys with fluid slag causes slag particles to

enter casting.

5. Cold shut, misrun, unfilled castings Low pouring temp, delay in pouring, due to many folds

being poured, loss of heat from lable, due to improper covering failure of ladle opening in the

bottom pouring cause premature solidification of metal causing defects.

6. Sand fusion, metal penetration, rough surface Excessive pouring temp of liquid causes

damage to the casting surface by attacking mould surface.

7. Sand erosion sand inclusions Uncontrolled high pouring rate from ladle into mould leads to

erosion of mould/core

PRECAUTIONS:

1. The furnace crucible should be clean and red hot for charging

2. Charge material should be free from oil, moisture etc.,

3. Melting must be done under steady condition to reduce gas pickup.

RESULT: Melting practice is observed

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PREPARATION MOULD CAVITY USING SPLIT PATTERN

Aim: To prepare a green mould for casting using only two boxes.

Tools And Pattern: Wooden pattern made in two halves, dowelled together, the division

passing through the center of the grooves; cope and drag moulding tools parting sand, brick dust

etc.

Stage Sketches: The mould can be prepared by using three boxes without any difficulty.

However the same can be prepared using two boxes using an ingenious method known as false-

core method.

Procedure:

1. One half of the pattern is molded in the bottom box, the parting being cut an incline as shown.

The other half pattern is then placed in position and sand poured and rammed to form the second

parting with a slope down wards from the upper flange of the pulley

2. The top box is next placed on the bottom box and properly located. Sand is poured and

rammed without damaging the false core.

3. The top box is gently removed; the upper half pattern is gently taken out from the top box.

4. The top box is replaced on the drag and the entire mould is turned upside down. The bottom

box, which now is at the top, is gently lifted and the remaining half of the pattern is withdrawn.

5. The bottom box is replaced and the mould id inverted. The spruces are removed, pouring basin

is cut and the mould is finished after piercing holes (vents).

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Observations:

1. After ramming using moulds hardness tester check the mould hardness on all the four sides of

the pattern.

2. Locate the rumen and riser 900 exactly.

Precautions:

1. Ramming should be uniform to impart uniform strength to the mould.

2. Apply parting sand at the partitions for easy separation of boxes.

3. Locate the two halves of pattern properly to avoid mismatch.

Result: Sand mould is prepared for the given pattern.

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PREPARATION OF MOULD CAVITY USING SINGLE PIECE PATTERN

Aim: To prepare a mould for a given single piece pattern

Material Required: Moulding sand, Facing sand, Baking sand, Parting sand, core, Pattern, Cope

box, Drug box, Bottom board.

Tools Required: Sprue, Riser, Chaplets, Gate cutter, Trowel, Vent rod, Sleek, Bellow

Flask: A moulding flask is one which holds the sand mould intact. Depending upon the position

of the flask, in the mould structure it is referred to by various names as drag cope and check. It is

made up of wood for temporary applications or more generally of metal for long term use.

Drag: lower moulding flask.

Cope: Upper moulding flask.

Check: Intermediate moulding flask used in three moulding

Pattern: Pattern is a replica of the final object to be made with some modifications. The mould

casting is made with the help of the pattern.

Parting Line: This is the dividing line between the two moulding flasks that makes up the sand

mould. In split pattern it is also the diving line between the two halves of the pattern.

Bottom Board: This is a board normally made of wood which is used at the start of the mould

making. The pattern is first kept on the bottom board sand is poured on it and then the ramming

is done in the drag.

Facing Sand: It is a specially prepared sand which is placed around the pattern which has

superior properties with regards to refractoriness permeability etc. this will ensure better surface

on the castings.

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Coal Dust: The small amount of carbonaceous materials sprinkled on the inner surface of the

moulding cavity to give better finish to castings.

Moulding Sand: It is a mixture of sicila, clay and moisture in appropriate proportions to get the

desired results and it surrounds the pattern facing sand while making the mould. The moulding

sand is the mixture.

Backing Sand: It is chat constitutes most of the refractory material found in the mould. This is

made up of used and burnt sand.

Core: It is used for making hellow cavities in castings.

Sprue: The passage through which the molten metal from the pouring basin reaches the mould

cavity. In many cases it control the flow of metal into the mould.

Runner: The passageways in parting plane through which molten metal flow is regulated before

they reach the mould cavity through the In – Gate.

Ingate: The actual entry point through which molten metal enter mould cavity.

Riser: It is a reservoir of molten metal provided in the casting so that hot metal can flow into the

casting when there is a reduction in volume of metal due to solidification.

Chill: Chill are metallic objects which are placed in the mould to increase the cooling rate of

molten metal

Procedure:

1. First a bottom board is placed either on the moulding platform or the floor making surface

ever.

2. The drag-moulding flask is kept upside down on the bottom board along with the drag part of

the

platform at the center of the flask on the board.

3. Dry facing sand is spri

Precautions:

1. There should be enough clearance between the pattern and the walls of the flask.

2. The ramming of the sand should be done properly so as not to compact it too hard, which

makes the escape of gases difficult.

Result: Mould for single piece pattern is prepared.

29


SAND PREPARATION AND STRENGTH & COMPRESSION TESTING

Aim: sand preparation and strength and compression testing for greensand moulds

Equipment requirements: Hand reamer Specimen Cylinder 100mm Height of a Dia 50mm.

Specimen Remover Hardness Tester Permeability Tester Universal Testing Machine Flat and

Stepped Discs

Material requirements: Green Sand 10Kgs Water-1Lit Bentonite powder -50grams Clay 1Kg

Composition of Sand Preparation: Green Sand 79-80% Water 3-6% Additives 10-15% Clay 6-

15%

Procedure: 1.Take the Dry Sand and it is grinded in the Muller to break the big pieces present

inits them observed

2.Sand is screened and them small contaminated material are removed in the sand and water is

added 3-6% depending upon amount of green sand, and mix well

3.In order to get good samples additives are mixed with the sand before watering

4.After mixing wet sand samples required is observed

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Precautions:

1.Don‟t mix More Water

2.Don‟t put the finger between the hand reamer and specimen remover 3.less thsn 75% hardness

is not Aceptable.

Results: Sand Preparation & Strength & Compression tested.

1.Value of Dry Compression__________________gm/cm2.

2. Value of Dry Shearing_____________________ gm/cm2.

3. Value of Green Compression_______________ gm/cm2.

4. Value of Green Compression_______________ gm/cm2

VIVA QUESTIONS:

1.what type of boxes are used in mouldpreparation

2. Centrifugally cast products have

3. Chills are used in moulds to

4. Directional solidification in castings can be improved by

5. The purpose of sprue is to

6. The process of pouring molten metal under high pressure in to mould,is known as (A )

7. The Draft on pattern for casting is

8. Shrinkage allowance is made by

9. Centrifugally cast products have

10. A slight taper inward on the vertical surface of a pattern is known as –

11. For ornamental parts and toys ofnon ferrous alloys --------- casting is used

12. A mixture of 70%sand and 30%clay is known as ------------ sand

13. To obtained high density and pure casting, --------- casting is used.

14. Water pipes of large length and diameter are made by ----------------

15. Core prints are provided on patterns --------------.

16. The patterns in the case of Machine moulding are mounted on ----------

17. For Gray cast Iron, the pattern shrinkage allowance is of the order of 7 to 10.5 mm/m.

18. To enhance the existing properties and to impart special propertiesfor the moulding sand ----

----------- are added.

19. In cemented moulds cement is used as a ---------------.

20. Investment moulding is also called as ---------------.

21.Describe the steps involved in casting

22.Describe the advantages of casting over methods.

33.What are the applications of castings?

24.What is Foundry ?.Describe about Foundry Layout.

25.What is Pattern ? Describe types of Patterns.

26. The function of a riser is_____________.

27. Gating system is designed for__________.

28. Common defect in castings is____________.

29. Hidden blowholes in castings can be detected by __________test

30. In shell moulding shells are made of____________ material.

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31. Max yield can be obtained by effective design of__________

. 32.Components obtained by centrifugal casting are of__________ thickness.

33.Example of components produced by shell moulding is_________.

34.Defect obtained by rapid pouring of molten into the mould is_________.

35. Extra portion projected from casting at parting line is _________.

36. Invisible cracks on the surface of castings can be detected by_____.

37 Number of castings produced by one sand mould is___(one/two).

38 Furnace is integral part of die in (hot chamber/cold chamber die casting).

39. Furnace is separated from die in (hot chamber/cold chamber die casting). 40. Advantage of

blind riser is______.

41. Rapid cooling of castings causes_____________________.

42. Stresses developed in castings relieved by________________.

43. Mechanical properties of castings can be improved by________.

44 Wax patterns are not removed from mould in________________.

45. Directional solidification means___________________

32


PATTERN MAKING

AIM: To prepare a wooden pattern detailed below with allowance.

TOOLS & EQUIPMENT REQUIRED Steel rule, Out side caliper, Mortise chisel, Inside

chisel, Peering chisel, Firmer chisel, Wood rasp half round file, Outside gauge, Outside chisel,

Try square, Handsaw, Mallet, Sandpapers

MATERIAL REQUIRED Teak wood given size

PROCEDURE: Match the two rectangular wood pieces of stock and fix them together by wood

screws at either end in the excess portion of wood. This must give a firm clamping of the wood

pieces to turn into single piece. In body portion of the pattern mark a center link using marking

gauge and extend it to the dressed end. Using the race with counter sunk make indentations at the

center of each and to form locations for the head stock and tail stock center. The wood stock is

turned on the wood turning lathe using appropriate gauge and finally finished the dimensions.

Sanding paper No. ½ or No.0 does smooth finishing. The sand paper should be moved laterally

on the rotating work

PRECAUTIONS

1. The tools are kept sharp to cut freely without burning and also without much pressure to

cause chipping.

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2. Maintain proper turning angles.

3. Be alert to avoid accidents.

2. RESULT The Required Split pattern is prepared by using of various tools like steel rule,

chisels, wood rasp files etc.

34


PLASMA ARC WELDING

AIM: To Join two given work pieces using plasma arc welding and Brazing and

cut the given plate into two parts using plasma cutting.

Apparatus required: Plasma Arc Welding System

Material Required: MS flat 50x50x10 mm – 3 Nos

Procedure

1. The edge of the given material is prepared to the required V-shape using

grinding machine.

2. The machine is set to the required parameters( For Welding).

3. Place the two work pieces on the table with required position as shown in figure.

4. The work pieces are kept in the required position and tack welding is performed

on the work pieces.

5. First run of welding is done to fill the gap and penetration of the weldment by

holding the electrode at about 700 and filler rod at 300 and move the electrode to

another end uniformly.

6. Second run of welding is done with proper weaving and uniform movement so

that a uniform weld bead will be obtained.

7. The scale formed is chipped with chipping hammer.

8. Filing is done to remove any spatter around the weld.

9. The machine is set to the required parameters( For Cutting).

Result:

35


CORE MAKING

1. TENSILE CORE BOX

Aim: To Prepare specimen to determine tensile strength.

MACHINE CONTAINS: This consists of a hopper, split core box with base plate.

PROCEDURE

1. Remove the two Allen Screw and Separate the clamp from the plunger head.

2. Insert the clamp on rammer plunger rod and place it on the plunger.

3. Hold the plunger head under rammer plunger and tight clamp with Allen Screw.

4. Lift the plunger by lifting cam.

5. Dismantle split core box from base plate by loosing Allen Screw for cleaning.

6 Assemble the split core box with hopper on base plate.

7. Insert the scrapper taking care that the cutting edge of the scrapper points downward and the

Cavity of the core box is clear for the scrapper.

8. Fill the core box with sand under the test and place it under plunger head.

9. Gently bring the plunger head down with lifting cam; taking care that plunger slides freely in

The split mould.

10. Rest the plunger head on the sand. Ram the sand by dropping the sliding weight 3 times by

Rotating ramming cam.

11. Lift the plunger by the lifting cam and remove the core box assembly from rammer base.

12. Pull out the scrapper to cut sample to standard height.

13. Remove the hopper.

14. Remove the excess sand carefully by any soft brush.

15. Place any suitable metal plate, remove the base plate and separate the split core box carefully

Without damaging the specimen.

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16. The specimen is ready for further process.

Result ;

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2. TRANSVERSE CORE BOX

AIM: To Prepare specimen to determine Transverse strength.

MACHINE CONTAINS: This consists of a hopper, split core box with base plate.

PROCEDURE.

1. Remove the two Allen Screw and Separate the clamp from the plunger head.

2. Insert the clamp on rammer plunger rod and place it on the plunger.

3. Hold the plunger head under rammer plunger and tight clamp with Allen Screw.

4. Lift the plunger by lifting cam.

5. Dismantle split core box from base plate by loosing Allen Screw for cleaning.

6. Assemble the split core box with hopper on base plate.

7. Insert the scrapper taking care that the cutting edge of the scrapper points downward and the

cavity of the core box is clear for the scrapper.

8. Fill the core box with sand under the test and place it under plunger head.

9. Gently bring the plunger head down with lifting cam; taking care that plunger slides freely in

the split mould. Rest the plunger head on the sand.

10. Ram the sand by dropping the sliding weight 3 times by rotating ramming cam.

11. Lift the plunger by the lifting cam and remove the core box assembly from rammer base.

12. Pull out the scrapper to cut sample to standard height. Remove the hopper.

13. Remove the excess sand carefully by any soft brush.

14. Place any suitable metal plate, remove the base plate and separate the split core box carefully

without damaging the specimen.

Result ;

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15. The specimen is ready for further process.

Result:

39


SAND TESTING

AIM: This instrument is used for determining the various strengths of prepared specimen.

MACHINE CONTAINS:

1. Hydraulic Unit With Loading Assembly, Quick Release Coupling.

2. Pressure Gauges (Low & High)

Low gauge — Range:-0- 1600 Gms/cm2

High gauge — Range: - 0- 13kg/cm2

3. Compression Pads

4. Oil Filling Funnel

OPERATING INSTRUCTION:

1. Take the instrument on plane platform.

2. Place the oil-filling funnel in quick release coupling.

3. Pour the oil in funnel, rotate the wheel clockwise & anticlockwise.

4. Repeat the procedure until the air bubbles do not appear in oil.

5. Then remove the oil-filling funnel and place the Low pressure gauge.

6. Place the compression pads in its location.

7. Put the cylindrical specimen in between two compression pads.

8. Rotate the wheel clockwise.

9. Loading piston applying the load on cylindrical specimen. See at the pressure gauge.

10. Pointer of the pressure gauge moves with reference pointer (Red pointer). When the

specimen

breaks, the Pointer of the pressure gauge will came back to its home position and reference

pointer indicates compression strength of specimen.

PRECAUTION:

1. Keep instrument clean.

2. Do not cross maximum range of pressure gauges.

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3. Use only hydraulic oil no. 150 - 2

Result:

41


TENSILE STRENGTH

AIM: To check the Tensile strength of Tensile specimen. With the help of universal strength

Machine

MACHINE CONTAINS:

1. A movable and a stationary jaw with rollers

2. Guide bracket

3. Two rods and knurled screw.

4. Adjustable ball pad

PRE-SETTING:

1. The knurled screw is removed from stationary jaw.

2. Insert the attachment as shown in the illustration and clamp the stationary jaw by knurled

Screw. Adjust the position of the rollers, So that flat side of roller will touch together (as shown

in illustration).

3. Then both jaws are pushed together.

OPERATING INSTRUCTIONS:

3. The Tensile specimen is placed in the jaws carefully.

4. Follow the same loading procedure adoBed for compression strength till sample breaks. Read

Compression strength (CS.) and multiply by factor provided from the Tensile strength (T.S.) on

inner scale of the gauge. (C.S. X 3.9275 = Tensile strength.)

PRECAUTION:

1. Keep the instrument clean.

Result:

42


PERMEABILITY TEST

AIM: To determine permeability number of green sand, core sand and raw sand.

OVERVIEW:

Permeability is that property which allows gas and moisture to pass through the moldings and . It

is determined by measuring The rate of flow of air through A . F . S . standard rammed

specimen under a standard pressure. The volume of air in cm 3/ min. passing through a specimen

of length 1 cm. and cross sectional area of 1 cm 2 under a pressure difference of 1 cm. water

gauge is called Permeability Number.

Permeability Number:

The volume of air passing through a sand specimen 1 sq. cm area and 1 cm. in height at a

pressure of 1 gram per square centimeter in 1 min. is called the Permeability Number and is

computed by the formula = (v x h) / (p x a x t) Where = Permeability Number v = Volume of air

passing through the specimen (cubic centimeter or in mil)h = Height of specimen (centimeters) p

= Pressure difference between upper and lower surfaces of test specimen (in centimeter of water

column)a =Cross-sectional area of specimen (square centimeter)t = time (minutes)

Permeability Meter:

The body of the Permeability Meter is an aluminum casting of a water tank and base. Inside

water tank floats a balanced air drum carefully weighed and designed to maintain constant

pressure of 10cm during its fall. The outlet from the air drum is connected to a centre post in the

base via three way air valve. The centre post incorporates a pipe for measuring pressure, which is

connected to the water manometer and an expandable “O” ring for sealing the specimen tube. It

also accommodates the orifices

MACHINE CONTAINS:

1. Water tank

2. Air tank

3. Manometer

4. Standard chart

5. Rubber boss

6. O-P-D valve

7. Orifices

OPERATING INSTRUCTIONS:

1. Place the instrument on leveled platform.

2. Take 'O-P-D' valve knob at 'D' position.

3. Close the opening of the air tube inside water tank by thumb and pour water up to the W'mark.

4. Insert air tank into water tank carefully.

5. A screw is provided at the left side of the manometer to fill the water in manometer.

Unscrewing the knob operates this screw and water is filled in the manometer.

6. The water level should coincide with the zero of the manometer scale The screw is closed by

tightening.

7. Final zero level is adjusted by opening 'zero adjust screw' provided in front of manometer

8. Selection of orifice it is recommended to use small orifice for permeability below 50Nos. and

large orifice for permeability above 50Nos.

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9. Tighten the orifice by fingers only. Take the specimen tube with rammed specimen and place

it inverted over the rubber boss.

10. Put the valve on 'P position. Read the height of the water column in the manometer tube.

Find out corresponding permeability number from the chart provided with the instrument.

11. Put the valve on '0' position. Whenever the air tank is flush with water tank, keep the valve

on'D' position and slowly lift the air tank to the top position.

12. Lift the air tank drum slowly up keeping the valve in 'D' position

PRECAUTIONS:

1. Keep the instrument dust proof.

2. Keep the instrument clean.

3. Lift the air drum only in 'D' Position to avoid any water entering the air passage.

4. For removal of the water tank completely from manometer

5. Use zero adjustment knob valves.

RESULTS:

44


Sand Rammer

Aim: Sand Rammer is used for preparing standard specimen under standard conditions.

MACHINE CONTAINS: 1. Main Body

2. Specimen Tube

3. Pedestal Cup

4. Stripping Post

Overview: The sand rammer is a machine for preparing specimens for testing of the permeability and strength

of moulding sand and is comprised mainly of a base, ram, tamping bar and lever. The machine is so

constructed that the ram is brought up by the crank and is then caused to drop to strike and drive

down the tamping bar at the lower end of which is fixed tamping plate which slides into a sand tube

to press the sand tube into a certain size with certain energy.

OPERATING INSTRUCTIONS: 1. Place the machine on non- vibrating platform.

2. Take the height such that the reading marks of the top bracket should be in eye level.

3. Place the Specimen Tube in the Pedestal Cup.

4. Fill approx. 135-160 grams Sand Sample in the Specimen Tube.

5. Lift the left cam upward;

6. Place the Specimen Tube with Pedestal Cup on the base.

7. Take Ramming head downward with left cam.

8. Ram the sample three times with the help of right cam.

9. See that the top of plunger rod matches the zero of the scale

10. It should match within + 1 mm.

11. Lift the left cam upward.

12. Take the specimen tube.

13. Place it on stripping post.

14. Pull the tube downward for removing the specimen.

PRECAUTION: . 21111,

1. Keep the instrument clean

2. Apply rust preventive oil to Moving Parts, Specimen Tube, and Pedestal Cup.

3. Do Not Ram Right Handle Without Specimen.

4. Lubricate All Moving Parts At Least Once In The Week.

45


HYDRAULIC PRESS AIM: To do bending and drawing operations on hydraulic press by using dies.

MATERIAL: CRCA (cold rolled cold annealing) sheet.

TOOLS AND ACCESSORIES: Hydraulic press dies.

THEORY:

Large machine parts can’t be forged by hand, since the comparatively light blow of a hand or sledge

hammer is unable to produce a great degree of deformation in the metal being forged. More over

hand forging is a lengthy process and requires heating of the metal, this has lead to the use of power

hammer and presses in forging machines, which work on pressure are called presses. Press forging is

done in presses rather than with hammers. Press forgings are generally more accurate dimensionally

than drop forgings. Hydraulic presses are load restricted machines in which hydraulic pressure moves

a piston in a cylinder. A chief feature is that the full press load is available at any point during the full

stroke of the ram. This feature makes the hydraulic press ideally suited for extrusion-type foreign

operations. The ram velocity can be controlled and even raised during the stroke. The hydraulic press

is a relatively slow speed machine. This results in longer contact time, which may lead to problems

with the heat loss from the work piece and die deterioration. On the other hand the slow squeezing

action of a hydraulic press results in close-tolerance forgings. Hydraulic presses area available in

rating from 500 to 18000 tons, although several presses with rating of 50000 tons have been built.

PROCEDURE: 1. Fix the die holder to the ram of the press.

2. Fix the top part of the die(punch) in the die holder and tighten it.

2. Raise the bed to the required height and place the bottom part of the die on it.

3. Place the material (CRCA Sheet) between the punch and die.

4. Close the release valve of the pump.

5. Operate the low pressure lever i.e. plunger with bigger dia. The ram will move very fast and touch

the job.

6. Then operate the high pressure lever i.e. plunger with smaller dia. The gauge will start

indicating the load.

7. Open the release valve, the ram will return to the original position.

PRECAUTIONS: 1. Punch and die should be aligned.

2. Apply the load up to the mark. Do not exceed the red mark given in the dial gauge.

RESULT: Thus bending and drawing operations are performed on hydraulic press.

46


FLY PRESS AIM: To do blanking and piercing operations on fly wheel press by using proper dies.

MATERIAL: CRCA (Cold Rolled Cold Annealing) sheet.

TOOLS AND ACCESSORIES: Fly wheel press, dies and required spanners.

THEORY AND DESCRIBION:

Blanking: It is a process in which the punch removes a portion of material from the stock which is a

strip of sheet metal of the necessary thickness and width. The removed portion is called a blank and is

usually further processed to be of some use. In this operation the cut out piece is of importance and in it

we can measure only the maximum diameter. Therefore incase of blanking operation the die should be

given exact size and the clearance should be made on the punch.

Piercing: Piercing also called sometimes as punching, is used for making hole in a sheet. It is identical

to blanking, except of the fact that the punched out portion coming out through the die is discharged as

scrap. In this case the left out piece is importance and in it the minimum diameter is measured. Thus the

punch should be given exact size and the clearance should be provided on the die. Fly wheel is used to

supply energy for that period of operation which requires more energy and during other periods, it

stores the energy. If machine lacks sufficient flywheel energy, it will come to stop and will not be able

to complete the operation. Actually by employing flywheel, we can work with motor of less capacity

and at the same time supply maximum tonnage at the desired used of operation. For faster working

operational (in case of blanking and piercing operations) more energy and power must be provided. In

case of blanking and piercing operations, the work is completed in a very brief portion of stroke. So in

this entire energy is to be tapped from flywheel, and flywheel supplies instantaneously whole energy

required for operation and for remaining period of cycle, it will restore.

PROCEDURE: 1. Fix the top part of the die (punch) in the fly press shaft and tighten it with nut.

2. Place the die on base of the fly press and fix with clamps.

2. Place the material in the die

3. Rotate the fly wheel, the shaft will come down and punch the material.

4. Lift the fly press shaft and remove the material from the die.

5. Repeat the cycle for the second operation.

PRECAUTIONS: 1. Die and punch should be aligned.

RESULT: Thus blanking and piercing operations are performed on fly press.

47


TUNGSTEN INERT GAS (TIG) WELDING

AIM: To prepare a V – Butt Joint Using TIG Welding.

MATERIAL AND APPARATUS REQUIRED: MS flat 50 x 60 X 10 mm3 ---2 No.s

Tong, Chipping Hammer, goggles,Tungsten Electrode, Ceramic Nozzle and Filler rod.

EQUIPMENT REQUIRED: Transformer, Rectifier and Argon gas cylinder.

THEORY:

The Endeavour of welder is always to obtain a joint which is as strong as the base metal and at

the same time, the joint is as homogeneous as possible. To this end, the complete exclusion of

oxygen and other gases which interfere with the weld pool to the detriment of weld quality is

very essential. In manual metal arc welding, the use of stick electrodes does this job to some

extent but not fully. In inert gas shielded arc welding processes, a high pressure inert gas flowing

around the electrode while welding would physically displace all the atmospheric gases around

the weld metal to fully protect it. The shielding gases most commonly used are argon, helium,

carbondioxide and mixtures of them. Argon and helium are completely inert and therefore they

provide completely inert atmosphere around the puddle, when used at sufficient pressure. Any

contaminations in these gases would decrease the weld quality.Argon is normally preferred over

helium because of a number of specificadvantages. It requires a lower arc voltage, allows for

easier arc starting and provides a smooth arc action. A longer arc can be maintained with argon,

since arc voltage does not vary appreciably with arc length. It is more economical in operation.

Argon is particularly useful for welding thin sheets and for out of position welding.The main

advantage of Helium is that it can with stand the higher arc voltages. As a result it is used in the

welding where higher heat input is required, such as for thick sheets or for higher thermal

conductivity materials such as copper or aluminium. Carbon dioxide is the most economical of

all the shielding gases. Both argon and helium can be used with AC as well as DC welding

power sources. However, carbon dioxide is normally used with only DC with electrode positive.

TUNGSTEN INERT GAS(TIG) WELDING:

Tungsten inert gas (TIG) welding is as inert gas shielded arc welding process using non

consumable electrode. The electrode may also contain 1 to 2% thoria mixed along with core

tungsten or tungsten with 0.15 to 0.4% zirconia. The pure tungsten electrodes are less expensive

but will carry less current. The thoriated tungsten electrodes carry high currents and are more

desirable because they can strike and maintain stable arc with relative ease. The zirconia added

tungsten electrodes are better than pure tungsten but inferior to thoriated tungsten electrodes.

48


It consists of a welding torch at the centre of which is the tungsten electrode. The inert gas is

supplied to the welding zone through the annular path surrounding the tungsten electrode to

effectively displace the atmosphere around the weld puddle. The TIG welding process can be

used for the joining of a number of materials though the most common ones are aluminium,

magnesium and stainless steel. The power sources used are always the constant current type.

Both DC and AC power supplies can be used for TIG welding. When DC is used, the electrode

can be negative (DCEN) or positive (DCEP). With DCEP is normally used for welding thin

metals where as fro deeper penetration welds DCEN is used. An Ac arc welding is likely to give

rise to a higher penetration than that of DCEP.

PROCEDURE

the work table in the required position.

49


Adjust the inert gas flow rate to the required rate.

and then separated by a small distance and the arc will be generated.

rk pieces.

that the filler metal will be deposited in the joint.

metal will be deposited on the work pieces.

PRECAUTIONS: 1. Never look at the arc with the naked eye. Always use a shield while welding.

2. Always wear the safety hand gloves, apron and leather shoes.

3. Ensure proper insulation of the cables and check for openings.

4. Select the parameters of the machine properly based on the metals to be

welded.

5. Set these parameters properly before performing the operation.

6. Inflammable and combustible materials are removed from the vicinity of welding

Operations

RESULT:

50


STUDY OF PROGRESSIVE DIE AIM: To study a progressive tool and perform blanking and piercing operations. To determine the punching force and blanking force theoretically and compare the same with obtained readings. TOOLS AND MATERIAL REQUIRED: Progressive tool, Clamps and Blank. EQUIPMENT REQUIRED: Hydraulic Press SPECIFICATIONS:

Capacity: 25 tons

Distance between columns: 865x300 mm2

Distance between ram to bed: minimum 180mm and maximum 915mm

Travel of ram: 180mm

Power of motor: 5 H.P. THEORY: SHEET METAL WORKING OR PRESS WORKING OF SHEET METAL Press working may be defined as a chip less manufacturing process by which various components are made from sheet metal. This process is also termed as cold stamping. The main features of a press are: A frame which supports a ram or a slide and a bed, a source of mechanism for operating the ram in line with and normal to the bed. The ram is equipped with suitable punch and a die block is attached to the bed .A stamping is produced by the down ward stroke of the ram when the punch moves towards and into the die block. The punch and die block assembly is generally termed as a”die set” or simply as a “die”. Press working operations are usually done at room temperature. In this process, the wall thickness of the parts remains almost constant and differs only slightly from the thickness of the initial sheet metal. The initial material in cold press working is: low carbon steels, ductile alloy steels, copper and its alloys, aluminium and its alloys, as well as other ductile materials from 10th of a mm to about 6 or 8 mm thick. Elastic recovery or spring back. In metal working processes, the total deformation imparted to a work piece will be the sum of elastic deformation and plastic deformation. We also know the elastic deformation is recoverable where as plastic deformation is permanent. So, at the end of a metal working operation, when the pressure of metal is released, there is an elastic recovery by the material and the total deformation gets reduced a little. This phenomenon is called as “Springback”.This phenomenon is of more importance in cold working operations, especially in forming operations such as bending etc .Spring back depends upon the yield point strength of a metal. The higher the yield point strength of a metal, the greater the spring back. The amount of spring back for a forming operation is difficult to predict and cut- and try methods are most satisfactory to account for it. To compensate for spring back, the cold deformation must always be carried beyond the desired limit by an amount equal to the spring back. Press operation: The sheet metal operations done on a press may be grouped into two categories, cutting operations and forming operations. In cutting operations, the work piece is stressed beyond its ultimate strength.

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The stresses caused in the metal by the applied forces will be shearing stresses. In forming operations, the stresses are below the ultimate strength of the metal. In this operation, there is no cutting of the metal but only the contour of the work piece is changed to get the desired product. The cutting operations include: blanking, punching, notching, perforating, trimming, shaving, slitting and lancing etc.The forming operations include: bending, drawing, redrawing and squeezing. The stresses induced in the metal during bending and drawing operations are tensile and compressive and during the squeezing operations these are compressive Blanking: Blanking is the operation of cutting a flat plate from sheet metal. The article punched out is called the „blank‟ and is the required product of the operation. The hole and metal left behind is discarded as waste. It is usually the first step of series of operations

Punching: It is a cutting operation by which various shaped holes are made in sheet metal .Punching is similar to blanking except that in punching , the hole is the desired product , the material punched out to form the hole being waste. Perforating: This is a process by which multiple holes which are very small and close together are cut in flat work material . Trimming: This operation consists of cutting unwanted excess material from the periphery of a previously formed component. Shaving: The edges of a blanked part are generally rough, uneven and un square. Accurate dimensions of the part are obtained by removing a thin strip of metal along the edges. Slitting: It refers to the operation of making incomplete holes in a work piece. Lancing: This is a cutting operation in which a hole is partially cut and then one side is bent down to form a sort of tab or louver. Since no metal is actually removed, there will be no scrap. Bending: In this operation, the material in the form of flat sheet or strip is uniformly strained around a linear axis which lies in the neutral plane and perpendicular to the lengthwise direction of the sheet metal. Drawing: This is a process of a forming a flat work piece into a hollow shape by means of a punch which causes the blank to flow into a die cavity. TYPES OF DIES: The dies may be classified according to the type of press operation and

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according to the method of operation. Types of press operation: According to this criterion, the dies may be classified as: cutting dies and forming dies. Cutting dies: The dies are used to cut the metal. They utilize the cutting or shearing action. The common cutting dies are: blanking dies, piercing dies, perforating dies, notching, trimming, shaving dies etc. Forming dies: These dies change the appearance of the blank without removing any stock. These dies include bending dies, drawing dies, squeezing dies etc.. Method of operation: According to this criterion, the dies may be classified as: single operation dies or simple dies, compound dies, combination dies, transfer dies, progressive dies and multiple dies.

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A progressive or follow on die has a series of stations. At each station an operation is performed on the work piece during a stroke of the press. Between strokes the piece in the metal strip is transferred to the next station. A finished work piece is made at each stroke of the press. A progressive die is shown in fig. while the piercing punch blanks out a portion of the metal in which two holes had been pierced at a previous station Thus after the stroke two holes will be punched each stroke of the press produces a required finished component. Principle of metal cutting: The cutting of sheet metal in the press work is a shearing process. The punch is of the same shape as of the die opening except that it is smaller on the each side by an amount known as „clearance‟. As the punch touches the material and travels downward, it pushes the material into the die opening. The material is subjected to both tensile and compressive stresses as shown in fig (a). Stresses will be highest at the edges of punch and die and the material will start cracking there. The various steps in the rupture or facture of material can be written as stressing the material beyond the elastic limits; plastic deformation reduction in area fracturing starts in the reduced area and becomes complete. If the clearance between punch and die is correct, the cracks starting from the punch and die edges will meet and the rupture is complete as shown in fig (b). If the clearance is too large or too small the cracks do not meet and ragged edge results due to the material being dragged Clearance: The die opening must be sufficiently larger than the punch to permit a clean fracture of the metal. This difference in dimensions between the mating members of a die set is called „clearance‟. This clearance is applied in the

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following manner:

Date post:	10-Apr-2018
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