DEPARTMENT OF MECHANICAL ENGINEERING
PRODUCTION TECHNOLOGY LAB MANUAL
Exp-1
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
WORK PIECE DIAGRAM
1
All Dimensions are in “MM”
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.
2. Maintain proper turning angles.
3. Be alert to avoid accidents.
RESULT
The Required Split pattern is prepared by using of various tools like steel rule, chisels, wood rasp files etc.
FINAL PATTERN
2
REVIEW:
3
Experiments different from JNTUH syllabus:
1. Prepare a single piece wooden pattern of cam detailed below with allowance.
All Dimensions are in “MM”
2. Prepare a split wooden pattern of dumbbell detailed below with allowance.
All Dimensions are in “MM”
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3. Prepare a split wooden pattern of stepped rod detailed below with allowance.
All Dimensions are in “MM”
4. Prepare a split wooden pattern of stepped pulley detailed below with allowance.
5
All Dimensions are in “MM”
5. Prepare a split wooden pattern of stepped bar detailed below with allowance.
All Dimensions are in “MM”
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6. Prepare a split wooden pattern of stepped rod detailed below with allowance.
All Dimensions are in “MM”
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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.
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 _________.
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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___________________
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Exp-2 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 in its 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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Equipment Diagrams.
Universal Strength Machine
Sand Reamer
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.
REVIEW:
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Exp-3 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.
Exp Diagram:
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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.
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.
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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.
REVIEW:
Experiments different from JNTUH syllabus:
1. Prepare a mould for a given single piece pattern cam.
All Dimensions are in “MM”
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Exp-4
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.
Exp Diagram:
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 esy separation of boxes.
3. Locate the two halves of pattern properly to avoid mismatch.
Result: Sand mould is prepared for the given pattern.
REVIEW:
Experiments different from JNTUH syllabus:
1. Prepare a mould for a given split piece pattern of stepped rod.
All Dimensions are in “MM”
2. Prepare a mould for a given split piece pattern of dumbbell.
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All Dimensions are in “MM”
3. Prepare a mould for a given split wooden pattern of stepped bar.
All Dimensions are in “MM”
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Exp-5
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 Alluminium 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:
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1. 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 nonFerrous melt causes this defect.
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.
REVIEW:
Experiments different from JNTUH syllabus:
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1. To observe the melting of wax to prepare the stepped pulley casting.
All Dimensions are in “MM”
2. To observe the melting of wax to prepare the cam casting.
All Dimensions are in “MM”
VIVA QUESTIONS:
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MELTING PRACTICE
1. How furnaces are classified? Explain crucible melting process.
2. Explain about Coupola Furnace, operations and reactions that take place inside the furnace.
3. What are the defects in casting?
4. How defects are rectified in castings?
5. What is the principle of centrifugal casting? Explain.
6. Describe hot chamber die casting and cold chamber die casting.
7. Explain about investment casting with figure.
8. What is shell moulding and list out its applications?
9. What is the principle of gating?
10. What are the types of gates and explain ingate ?
11. The method of casting in which the molten metal is fed into the metallic mould by gravity is known as
12. In which of the following casting method, the molten metal is poured and allowed to solidify while the
mould is revolving
13. In a hot chamber die casting method
14. A casting defect which results in general enlargement of a casting is known as
15. In a pressurized gating system the total cross sectional area at in gates, to the mould cavity than at the
sprue base is
16. Misalignment of the moulding boxes leads to which of the following casting defect?
17. In a hot chamber die casting machine
18. In which of the following moulding process the pattern with in the mould is not taken out of the mould
before pouring of molten metal
19. The solidification time of metal in a feeder head should be _______ than that in the mould cavity
20. Cast iron and steel pipes are produced by
21.How furnaces are classified? Explain crucible melting process.
22.Explain about Coupola Furnace, operations and reactions that take place inside the furnace.
23.What are the defects in casting?
24.How defects are rectified in castings?
25.What is the principle of centrifugal casting? Explain.
Exp-6
PREPARATION OF BUTT JOINT USING ARC WELDING
AIM: To prepare Joints for welding suitable for butt- welding and lap welding.
TOOL & EQUIPMENT REQUIRED:
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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.
EXPERIMENT DIAGRAM FOR V BUTT JOINT:
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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.
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 th results
are to be compared.
Result : To prepared Joints for welding suitable for butt- welding by using of various tools and equipments
REVIEW:
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Exp-7
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.
EXPERIMENT DIAGRAM FOR LAP JOINT:
24
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 .
REWIEW:
25
Experiments different from JNTUH syllabus:
1. Prepare T-Joint from the given MS material 50 x 50 x 5mm.
2. Prepare L-Joint from the given MS material 50 x 50 x 5mm.
3. Prepare H-Joint from the given MS material 50 x 50 x 5mm.
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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Exp-8
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
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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 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 = I2RT,
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.
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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.
EXPERIMENT DIAGRAM:
PROCEDURE:
1. Switch on the machine and set the current in the machine to 2 Ampere
2. Set the timer to two seconds
3. Over lap 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:
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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.
REVIEW:
Experiments different from JNTUH syllabus:
Study the effect of the current on weld strength-using spot welding process by welding given MS pieces of
size 4”x2” to obtain the following alphabets.
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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Exp-9
PREPARATION OF BUTT WELDING USING GAS WELDING
Aim: To make butt-welding using gas welding equipment.
Equipment And Material Required:
Oxy – Acetylene welding outfit,
MS Sheets 50x50x1mm (2No)
Tools Required:
Wire brush,
Hand gloves,
Chipping hammer,
Spark lighter.
Work piece Diagram;
Procedure:
1. Acetylene valve on the torch is opened slightly and lightened with the help of a spark lighter.
2. Now acetylene valve is opened to get required the flow of acetylene.
3. Oxygen valve is opened till the intermediate flame feather reduces into inner cone to get a neutral flame.
4. The torch tip is to be positioned above the plates so that white cone is at a distance of 1.5mm to 3mm
from the plates.
5. Torch is to be held at an angle of 300 to 450 to the horizontal plane.
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6. Now filler rod is to be held at a distance of 10mm from the flame and 1.5 mm to 3 mm from the surface of
the weld pool.
7. As the backward welding allows better penetration, back ward welding is to be used.
8. After the completion of welding, slag is to be removed by means of chipping hammer, wire brush.
Precautions:
1. Ensure that torch movement is uniform.
2. See that the joints are extremely clean.
Result: A butt joint is prepared using gas welding process.
REVIEW:
Experiments different from JNTUH syllabus:
1. Prepare T-Joint from the given MS material 50 x 50 x 5mm by Gas Welding.
2. Prepare L-Joint from the given MS material 50 x 50 x 5mm by Gas Welding.
Exp-10
BRAZING
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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.
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BRAZING JOINTS
1.Bolts:
2. Pipes:
34
3. Nipples and flanges
4.CONTAINERS(SHEET BOXES)
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
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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.
REVIEW:
Experiments different from JNTUH syllabus:
1. Prepare Capillary Tube U-Joint by joining the given capillary rods of diameter 6 mm by brazing
process.
2. Prepare Capillary Tube -Joint by joining the given capillary rods of diameter 6 mm by brazing
process.
Exp-11
MECHANICAL PRESS WORKING
36
Aim: To make mosquito coil stand/washer/lid using Hydraulic press.
Equipment:
Hydraulic Press,
Compound Die,
Progressive Die,
Deep-Drawing Die.
Raw Material: Mild Steel
Description of the equipment:
Presses are classified in various ways. They may be classified according to
i. Source of power
ii. Method of actuation of the rams (slides)
iii. Number of slides
iv. Types of frames
v. The type of work for which the press has been designed.
Source of power: Two kinds of sources of power supply to the ram: Mechanical and hydraulic.
Mechanical presses, the energy of flywheel is utilized which is transmitted to the work piece by gears,
cranks, eccentrics or levers.
The flywheel rotates freely on the crankshaft and is driven from an electric motor through gears or v- belts.
The motors runs continuously and stores energy in the flywheel. When the operator presses a foot treadle or
actuates a button, the clutch gets engages and the flywheel is connected to the crankshaft. (Driveshaft).
Starts rotating and the stored up energy in the flywheel is transmitted to the ram on its downward stroke. The
clutch to engage and disengaged the flywheel to the drive shaft can be; a Jaw clutch and the air operated
clutch or an electro magnetic clutch. In manually operated mechanical presses, the clutch is disengaged to
each cycle. But in automatic presses in which the metal strip is fed to the die automatically, there is no need
of single stroke clutch. Disengaging mechanism and the ram moves up and down continuously. These
presses can be classified as plain and geared press, the flywheel is carried on a auxiliary shaft which is
connected to the main shaft. Through one or more gear reduction, depending upon size and energy needed.
In this arrangement, the flywheel stores considerably more energy than the plain as its speed is higher than
the main drive shaft.In Hydraulic press, the ram is actuated by oil pressure on a piston in a cylinder.
37
Mechanical presses have following advantages over the hydraulic presses.
1. Run faster
2. Lower maintenance cost
3. Lower capital cost.
Advantages of hydraulic presses are
1. More versatile and easier to operate
2. Tonnage adjustable to zero to maximum
3. Constant pressure can be maintained through out the stroke
4. Force and speed can be adjusted through out the stroke.
5. Safe as it will stop at a pressure setting.
6. The main disadvantages of hydraulic press is that it is slower than a mechanical press.
A press is rated in tones of force; it is able to apply with out undue strain. To keep the deflections small, it is
a usual practice to choose a press rated 50 to 100 percent higher than the force required for an operation.
Procedure:
1. Set the compound die or progressive die or deep drawing die in the required position.
2. Switch on the motor to start the machine.
3. Pass the MS sheet in to the progressive die/compound die. In case of deep drawing
4. Apply injection pressure using direction control valve.
5. The plunger punches the sheet into the mosquito coil stand/washer lid shape.
6. Release injection pressure.
7. Take out the finished product from the die.
8. Switch off the motor.
Precautions:
1. Do not apply too high injection pressure
2. Proper lubrication must be done between moving parts of die and press
3. Operate the hydraulic press carefully.
Result: Mosquito coil stand/Washer/lid is prepared using corresponding die un hydraulic press.
REVIEW:
38
Exp-12
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.
39
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:
40
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)
turn
changes
the
steel
into
which
in
structural
a
curved
shape (strain). If
you look at the
diagram
steel
below,
ductile, and after a
is
very
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.
41
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 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.
REVIEW:
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
5. The process which takes place below recrystallization temperature is known as
42
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 ------------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 --------------
43
Exp-13
INJECTION MOULDING PROCESS
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.
44
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.
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.
REVIEW:
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.
45
Exp-14
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.
46
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)
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.
REVIEW:
VIVA QUESTIONS:
47
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 _______
48
OVERALL VIVA QUESTIONS
1. What are the various parts in the wood turning lathe?
2. List different types of pattern?
3. What are the operations in making the pattern?
4. Define welding?
5. Give classification of welding process?
6. Define Arc welding?
7. What is effect of polarity on weld strength?
8. How much gap should maintain between weld rod and work piece?
9. What type of flux used on weld rods?
10. What is the minimum voltage for arc initiation?
11. What is the effect of current on weld strength?
12. What are different arc welding processes?
13. Differentiate between MIG and TIG welding?
14. Define spot welding?
15. What is seam welding?
16. Which type of electrode is used in spot welding?
17. What is the maximum thickness of the sheets that are spot welded?
18. What is difference between arc welding and gas welding?
19. What are the types of flames used in welding of MS plates?
20. What do you mean by backward welding and forward welding?
21. Which type of flame is used in welding of MS plates?
22. Which type of gas welding is used in welding of MS plates?
23. What is brazing?
24. What type of flame is used for brazing?
25. What is the difference between brazing and welding?
26. Difference between brazing and soldering?
27. What are the advantages of hydraulic press?
28. What is the difference between compound die and progressive die?
29. Define Deep-drawing operation?
30. Give the classification of presses?
31. Define Injection moulding process?
32. Which type of injection is used in this experiment?
33. What is raw material used in injection moulding?
34. Why oil cooler provided in this equipment?
35. Define Blow moulding process?
36. Differentiate between thermosetting and thermoplastics?
37. What is the raw material used in blow moulding?
38. Which type of compressor used in this experiment?
39. Differentiate between hydraulic and pneumatic pressure
49
MELTING POINTS OF SOME METALS AND ALLOYS
Metal
Melting Point
( C)
(oF)
Admiralty Brass
Aluminum
Aluminum Alloy
Aluminum Bronze
Antimony
Babbitt
Beryllium
Beryllium Copper
Bismuth
Brass, Red
Brass, Yellow
Cadmium
900 - 940
660
463 - 671
600 - 655
630
249
1285
865 - 955
271.4
1000
930
321
1650 - 1720
1220
865 - 1240
1190 - 1215
1170
480
2345
1587 - 1750
520.5
1832
1710
610
Cast Iron, gray
Chromium
Cobalt
Copper
Cupronickel
Gold, 24K Pure
Hastelloy C
Inconel
Incoloy
Iridium
Iron, Wrought
Iron, Gray Cast
Iron, Ductile
Lead
Magnesium
Magnesium Alloy
Manganese
Manganese bronze
Mercury
Molybdenum
Monel
Nickel
1175 - 1290
1860
1495
1084
1170 - 1240
1063
1320 - 1350
1390 - 1425
1390 - 1425
2450
1482 - 1593
1127 - 1204
1149
327.5
650
349 - 649
1244
865 - 890
-38.86
2620
1300 - 1350
1453
2150 - 2360
3380
2723
1983
2140 - 2260
1945
2410 - 2460
2540 - 2600
2540 - 2600
4440
2700 - 2900
2060 - 2200
2100
621
1200
660 - 1200
2271
1590 - 1630
-37.95
4750
2370 - 2460
2647
Niobium
2470
4473
3025
1555
3186
1965
5477
2831
5767
3569
(Columbium)
Osmium
Palladium
Rhenium
Rhodium
Metal
o
Phosphorus
Platinum
Plutonium
Potassium
Red Brass
Phosphorus
Platinum
Plutonium
Rhenium
Rhodium
Ruthenium
Selenium
Silicon
Silver, Coin
Silver, Pure
Silver, Sterling
Sodium
Steel, Carbon
Steel, Stainless
Tantalum
Thorium
Tin
Titanium
Tungsten
Uranium
Vanadium
Yellow Brass
Zinc
Zirconium
Ruthenium
Selenium
Silicon
Silver, Coin
50
Melting Point
( C)
(oF)
o
44
1770
640
63.3
990 - 1025
44
1770
640
3186
1965
2482
217
1411
879
961
893
97.83
1425 - 1540
1510
2980
1750
232
1670
3400
1132
1900
905 - 932
419.5
1854
2482
217
1411
879
111
3220
1180
146
1810 - 1880
111
3220
1180
5767
3569
4500
423
2572
1615
1761
1640
208
2600 - 2800
2750
5400
3180
449.4
3040
6150
2070
3450
1660 - 1710
787
3369
4500
423
2572
1615
VARIOUS PLASTIC MELTING POINTS
Material
Acetal (CoPo)
Acetal (HoPo)
Acrylic
Acrylic (Mod)
ABS (MedImp)
ABS (HiImpFR)
CelAcetate
CelButyrate
CelPropionate
EVA
LCP
Nylon (6)
Nylon (6/6)
Polyamide-imide
Polyarylate
TFE
PBT
PCT
Peek
PET
Polycarbonate
Polyetherimide
Polyethylene (LD)
Polyethylene (HD)
Polypropylene
Polystyrene (GP)
Polystyrene (MI)
Polystyrene (HI)
Polysulfone
PPO
PVC (Rig/Flex)
51
Degrees(OF)
400
425
425
500
400
420
385
350
350
350
500
500
525
650
700
600
500
580
720
540
550
700
325
400
350
350
380
390
700
575
350/325