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St.MARTIN’S ENGINEERING COLLEGE

DEPARTMENT OF

MECHANICAL ENGINEERING

PRODUCTION TECHNOLOGY LAB

[SUBJECT CODE:-A40312 ]

LAB MANUAL

DEPARTMENT OF MECHANICALENGINEERING

Document No:

DATE OF

COMPLIED BY:

B SRINIVASULU LLL L

AUTHORISED BY

SMEC/ME/LAB /MANUAL/PT

ISSUE:02/07/2016 Mr.B SRINIVASULU Ms.L. SWETHA

D.V.SRIKANTH

MECH (HOD)

\

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PRODUCTION TECHNOLOGY LABORATORY

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PRODUCTION TECHNOLOGY [SUBJECT CODE:-A40312]

LIST OF EXPERIMENTS

S.No. Name of the Experiment

1 PATTERN DESIGN AND MAKING (CONNECTING ROD)

2 PREPARATION OF MOULD CAVITY USING SPLIT PATTERN

3 PREPARATION OF MOULD CAVITY USING SINGLE PIECE PATTERN

4 MELTING AND CASTING PRACTICE

5 PREPARATION OF BUTT JOINT USING ARC WELDING

6 PREPARATION OF LAP JOINT USING ARC WELDING

7 PREPARATION OF LAP JOINT USING SPOT WELDING

8 PREPARATION OF BUTT WELDING USING TUNGSTEN INERT GAS (TIG)

WELDING

9 PREPARATION OF BUTT WELDING USING PLASMA WELDING

10 PREPARATION OF BUTT JOINT USING OXY-ACETELYENE BRAZING PROCESS

11 HYDRAULIC PRESS WORKS-ROD BENDING

12 HYDRAULIC PRESS WORKS- DEEP DRAWING

13 PREPARATION OF ALUMINIUM WASHER BY USING FLY WHEEL PRESS

14 PROCESSING OF PLASTICS-INJECTION MOULDING

15 PROCESSING OF PLASTICS-BLOW MOULDING

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Experiment-1:PATTERN DESIGN AND MAKING (CONNECTING ROD)

1.1 OBJECTIVE: To design and prepare a wooden pattern detailed belowwith allowance.

1.2 RESOURCES:

S.NO Name of the Equipment

Quantity

1 Steel rule 1

2 Outside caliper 1

3 Mortise chisel 1

4 Inside chisel 1

5 Peering chisel 1

6 Firmer chisel 1

7 Outside chisel 1

8 Try square 1

9 Handsaw 1

10 Sandpapers 1

11 Teak wood 1

1.3 PRECAUTIONS:

a) Thetools arekept sharp to cut freelywithout burning andalso without much

pressure to cause chipping.Maintain proper turning angles.

b) Be alert to avoid accidents. 1.4. WORKPIECEDIAGRAM:

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1.5 ALLOWANCES:

A pattern is always larger in size when compared to normal casting, because it carries certain allowances due to mechanical reasons and metallurgical reasons for example, shrinkage allowance is the result of

metallurgical phenomenon whereas machining, draft, and other allowances are provided on the patterns because of mechanical

reasons. The various pattern allowances are:

(a) Shrinkage or contraction allowance.

(b) Machining or finishing allowance.

(c) Draft or taper allowance.

(d) Distortion or camber allowance.

(e) Shake or rapping allowance. Among them shrinkage and draft

allowances are important

1.6 REQUIRED FINISHED PRODUCT: Design a Pattern for the casting shown in fig. which is to be made of steel by

considering Shrinkage and Draft allowance

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Solution: Shrinkage Allowance : Shrinkage Allowance is 21mm/m. For dimension 25, allowance is 25 x 21/1000 = 0.52 ~ 1.0

For dimension 15, allowance is 15 x 21/1000 = 0.31~ 1.0

For dimension 50, allowance is 50 x 21/1000 = 1.05

For dimension 30, allowance is 30 x 21/1000 = 0.63~ 1.0

Draft Allowance:

It is given to all surfaces perpendicular to the parting line. Draft

allowance is given so that pattern can be easily removed from molding

material which is tightly packed around it with out damaging the mold

cavity. The amount of Taper depends upon

Shape and size (length) of the pattern in the depth

direction in contact with the mold cavity.

Molding methods.

Mold materials.

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Draft allowance is imparted on internal as well as external surfaces; of

course it is more on internal surfaces.

Taper on external surfaces = 10 to 25

mm/meter or 10 - 20. Taper on internal

surfaces = 40 to 65 mm/meter or 30 – 40.

Assume 20 taper for external details and 40 for

internal details. For the above casting taper required

After providing this taper .The procedure for preparing the pattern is

given below.

1.7 PROCEDURE:

1. The given work piece is prepared using the Jack plane.

2. The work piece is cut by using sawing tools according to the

dimensions shown in figure

3. Finish the same using wood rasp file

4. Finish the work using emery paper.

1.8 RESULT:Designed and prepared a wooden piece connecting rod pattern

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1.9 POST LAB 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 ……………………………

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 ---------------.

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Experiment-2: PREPARATION MOULD CAVITY USING SPLIT PATTERN

2.1 OBJECTIVE: To prepare a mould cavity for a stepped circular split pattern.

2.2 RESOURCES : Teak wood of 70 x 70 x 150 mm3

Hack Saw, Jack Plane, Steel Rule, WoodWorking Lathe, Vernier Calipers and

Emery Paper.

2.3 THEORY:

A pattern is a mold forming tool in the hands of foundry men.

A pattern is the model or the replica of the object to cast.

Except for the various allowances a pattern exactly resembles the casting to be made.

A pattern may be defined as a model or form around which sand is

packed to give rise to a cavity known as mould cavity in which when molten metal is poured, the result is CAST OBJECT.

Functions of a Pattern:

A pattern prepares a mold cavity for the purpose of making a casting.

A pattern may contain projections known as core prints if the casting requires a core and need to be hallow.

Runner, gates and risers (used for introducing and feeding molten metal to the mold cavity) may form the part of the pattern.

A pattern may help in establishing locating points on the mold and therefore on the casting with a purpose to check the casting dimensions.

Pattern establishes the parting line and parting surfaces in the mold.

Patterns properly made and having finished and smooth surfaces reduce casting defects.

Properly constructed patterns minimize overall cost of the castings.

Pattern Making Tools:

The following tools are used for different purposes by a pattern maker.

(a) Measuring, Making and Layout Tools

(i) Steel rule (ii) Shrinkage rule

(ii) Caliper (iv) Divider

(v) Marking gauge (vi) Trammels

(vii) Try square (viii) T-bevel

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(ix) Combination square.

(b) Tools for clamping purposes:

(i) Hand vice (ii) Pattern makers vice

(iii) Bar clamp (iv) C-clamp

(v) Hand screw

(vi) Pinch dog ( to hold wooden pieces together for joining etc.).

(c) Sawing Tools:

(i) Coping saw (ii) Bow saw

(iii) Compass saw (iv) Rip saw

(v) Crosscut saw (vi) panel saw

(vii) Back saw (viii) Dovetail saw

(ix) Miter saw with miter box.

Wood Working Lathe:

The woodworking lathe is one of the most important machines

used in a carpentry shop. This is employed primarily for turning jobs in

making cylindrical parts. However, by suitably manipulating the tools,

tapers, radii, and other irregular shapes can also be easily turned.

It resembles the „engine lathe‟ most frequently used in the

machine shop and consists of a cast iron bed, a head stock, tail stock,

tool rest, live and dead centers, and a speed control device (shown in

Fig). The drive, in modern lathes, is individual motor driven; and a

cone pulley on the head stock spindle is connected by a belt to a cone

pulley on the motor shaft.

In practice, the work piece is either clamped between two

centers or on a face plate. Long jobs are held between the centers and

turned with the help of gouge, skew chisel, parting tool, etc. Generally,

the lathe is supplied together with a number of accessories for making

it useful for a variety of jobs. The size of a woodworking lathe, as in

the engine lathe, is usually specified in terms of the so-called “swing”

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of the lathe and the maximum distance between centers.

2.4 WORKPIECE DIAGRAM:

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2.5 PROCEDURE:

1. The given work piece is prepared using the Jack plane.

2. The work piece is cut by using sawing tools according to the

dimensions shown in figure

3. Finish the same using wood rasp file

4. Fix the work piece on wood working lathe.

5. Fix a dead center in the tail stock.

6. Perform operations according to the dimensions shown in figure

7. Finish the work using emery paper.

8. 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

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

poured and rammed without damaging the false core.

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

11.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.

12.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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2.6 PRECAUTIONS:

1. The work piece should be held rigidly in the vice while

performing cutting operation.

2. The work piece should be held rigidly in the chuck of lathe.

3. Make sure that the axis of drill coincides with the axis of work. Optimum machining conditions should be maintained.

2.7 RESULT:Preparation of a mould for a stepped circular split pattern is done.

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EXPERIMENT-

3PREPARATIONOFMOULDCAVITYUSINGSINGLEPIECEPATTERN

3.1 OBJECTIVE: To prepare a mould foragiven single piece pattern

3.2 RESOURCES:

S.NO Name of the Equipment Quantity

1 Moulding sand 10 Kg

2

Facing sand, Baking

sand 1 kg

3 Parting sand ½ kg

4 Pattern 1

5 Cope box 1

6 Drug box 1

7 Bottom board 1

8 Sprue, Riser 1

9 Chaplets 1

10 Gate cutter 1

11 Trowel 1

12 Vent rod 1

13 Sleek 1

14 Bellow 1

3.3 PRECAUTIONS: 1. Thereshould be enough clearancebetween thepattern and the walls of the flask. 2. The ramming of thesand should be doneproperlyso as not to compact it too

hard, which makes the escape of gases difficult.

3.4 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. Sand is poured and rammed without damaging position of pattern

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

from the top box.

5. 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.

6. The bottom box is replaced and the mould is inverted. The sprues are

removed, pouring basin is cut and the mould is finished after piercing holes (vents).

3.5 DIAGRAM :

3.6 RESULT:Mould for singlepiecepattern is prepared.

3.7 POST LAB QUESTIONS :

1. Advantageof blind riser is______.

2 . Rapid coolingofcastings causes_____________________.

3. Stresses developed incastingsrelieved by________________.

4. Mechanical properties of castings can be improved by________.

5. Waxpatterns arenot removed from mould in________________.

6. Directional solidification means___________________

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EXPERIMENT-4 MELTING AND CASTING PRACTICE

4.1 OBJECTIVE :To observe the meltingof Aluminum alloy to preparethe casting

for a connecting rod

4.2 RESOURCES :

S.NO Name of

the

Equipment

Quantity

1 Electric

furnace 1

2 Metal 1 kg

3 Crucible Graphite of Dia 1 „ x height

1.5‟‟

4 Ladle to sir 1

4.3 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.

4.4 PROCEDURE:

MeltingProcedureForAluminumAlloys:- The chargematerials, chemicals should be freefrom moisture, oil, and corrosion powder and should bepreheated before charging. The calculation of chargeshould be done consideringthe melting lossofeachelement in the melting furnaceforfinal desiredanalysis.

1. Thefurnace crucible should be cleanand red hot for charging.

2. Aluminumalloysgetreadilyoxidized and form dross, usingproper

coveringtopwith fluxand chemicals help to reducethis. Different

proprietarychemicals are available for different alloys.

Meltingshould bedone under steadyconditions withoutagitation. Stirringis

done to reduce gas pickup.

3. Oncemeltingis complete, degassingusingsolid chemicals like hexachloro-

ethanewhich evolves chlorine bypurgingwith nitrogenor argongas is done

toremove the dissolved hydrogen.Hydrogen is evolved from moisture.

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4. 3H2O+2Al→Al2O3+6H

5. Hydrogen absorbed byliquid metal causes serious porosityin

castingduringsolidification. Degassingshould be done in the temperature

range 7300C to 750

0C

6. Liquid metal after degassingis treated with sodium containingchemicals to

improvemechanical properties.

7. Liquid metal once readyshould not be super heated. Agitated or kept longin

the furnace whichwill cause dressing andgas pickup.Dross should be skimmed

properlybeforepouring.

8. Alloys containingmagnesium should be meltingcarefullyas it is highlyreacting.

Special fluxes and chemicals like sulphur are usedto inhibit the reactivityand

prevent spontaneous ignition, meltingloss and dross.

4.5 CASTINGDEFECTSDUETOIMPROPERMELTING:

1. Improperchemicalanalysis: Incorrectcharge, calculations, includingwrong

estimates of meltinglosses,metal recovery, excessive losses dueto improper

fluxingand sloggingoperations, improper coveringof non-Ferrous melt causes

thisdefect.

2. Gassymetal/hydrogenpickup/pinholeporosity:unclean meltingcauses

formation and absorptionof hydrogen into liquid metal. As castingsolidifies,

the absorbed hydrogen losses solubilityandformscavities inside casting.

3. Oxygenabsorption Excessiveoxygenfurnace operations in atmosphere

followingoxidation duringmelting cause this defect.It also causes loss of

costlymetal added in the charge.

4. SlaginclusionsImproper fluxing and slagremoval slagparticles to be mixed in

the metal beingpoured. Careless pouring, lip pouring for alloys with fluid

slagcauses slagparticles to entercasting.

5. Coldshut,misrun,unfilledcastingsLow pouring Temp, delayin pouring, dueto

manyfolds beingpoured, lossof heat from lable, dueto improper covering

failure of ladle openingin thebottom pouring cause prematuresolidification

ofmetal causingdefects.

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6. Sandfusion,metalpenetration,roughsurface Excessivepouringtempof liquid

causes damage to the castingsurfacebyattackingmould surface.

7. Sanderosionsandinclusions Uncontrolled high pouringrate from ladle into

mould leads to erosion ofmould/core

4.6 DIAGRAM :

4.7 RESULT: Meltingpracticeis observed.

4.8 POST LAB QUESTIONS :

1. Howfurnacesare classified?Explain crucible meltingprocess.

2. Explain about CoupolaFurnace, operations and reactions that takeplace inside

the furnace. What arethe defects in casting?

3. Howdefects are rectifiedin castings?

4. What is the principle ofcentrifugalcasting?Explain.

5. Describehotchamberdie casting and coldchamber diecasting.

6. Explain about investmentcasting with figure.

7. What is shell moulding and list outits applications?

8. What is the principle ofgating?

9. What arethetypes of gates and explain ingate ?

Themethod of castingin which themolten metal isfed into the metallic

mouldby gravityis known as ……………………..

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EXPERIMENT -5 PREPARATIONOFBUTTJOINTUSINGARCWELDING

5.1 OBJECTIVE :To prepare a butt joint by using arc welding

5.2 RESOURCES :

S.NO Name of the Equipment Quantity

1 Scale 1

2 Scriber 1

3 Hand hack saw 1

4 Flat file 1

5 Swing scale protector 1

6 Welding machine 1

7 gloves, 1

8 Shield 1

9 Wire brush 1

10 Chipping hammer 1

11 Welding rod 1

5.3.PRECAUTIONS:

1. Wearapron,shoes,nosemask,glovesandtight

fittedclothes.Becarefulandattentivewhile workingonweldingjob.

2. Duringweldingdon‟tseetheweldinglightragedirectlywithoutthe gagglefaceshield.

3. Donotcoolthe Weldingpieceinwater.

4. Donotkeepelectrodeholder ontheweldingmachine.

5. Noinflammable materialshouldbe presentinweldingshop.

5.4 PROCEDURE:

1. Given 2 M.S. plates arefilled at an angle of 450at 2 surfaces to be joined(V

groove is formed)

2. Electrodeis fixed to electrodeholder.

3. Connections to be given such that electrode- negativeand work piecepositive.

Weldingis to be donecarefullyforthe half-length of the plates.

4. Theworkpieces to be cut into two halvesby hacksaw.

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5. Thebeadsarepolished, etched with two percentnatal solution and studied

under themicroscopewhose magnification factors 10X forthe heat effected

zone.

6. Bygrippingthe beads b/w the jaws Tensiletestingmachine and load is applied

until the work piece breaks and the readings is to be noted.

7. Thesameprocedure is repeated fortheremaininghalfwhich is weldedbyreverse

polarityand theresults areto becompared.

5.5 DIAGRAM:

5.6.RESULTS :

prepared V butt Joint for given MS work pieces by using arc welding

5.7 POST LAB QUESTIONS :

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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.

EXPERIMENT – 6 PREPARATION OF LAP JOINT USING ARC WELDING

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6.1 OBJECTIVE : To prepare a LAP joint for given MS sheets by using arc welding

6.2 RESOURCES :

6.3 PRECAUTIONS :

1. Wearapron,shoes,nosemask,glovesandtight

fittedclothes.Becarefulandattentivewhile workingonweldingjob.

2. Duringweldingdon‟tseetheweldinglightragedirectlywithoutthe gagglefaceshield.

3. Donotcoolthe Weldingpieceinwater.

4. Donotkeepelectrodeholder ontheweldingmachine.

5. Noinflammable materialshouldbe presentinweldingshop.

6.4 PROCEDURE :

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.

S.NO Name of the Equipment Quantity

1 Scale 1

2 Scriber 1

3 Hand hack saw 1

4 Flat file 1

5 Swing scale protector 1

6 Welding machine 1

7 gloves, 1

8 Shield 1

9 Wire brush 1

10 Chipping hammer 1

11 Welding rod 1

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6.5 DIAGRAM:

6.6 RESULT:

To prepared Joints for welding suitable for lap welding

6.7 POST LAB QUESTIONS:

1. What is ARC blow in arc welding?

2. What are the gases used in gas welding?

3. Write about forge welding and its application.

4. Write about resistance welding and its application.

5. What is thermit welding? Explain its applications.

6. what is the phenomena of weld decay occurs in?

EXPERIMENT-7 PREPARATIONOFLAPJOINTUSINGSPOTWELDING

7.1 OBJECTIVE:To prepare a lap Joint on the given work pieces using spot welding

equipment.

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7.2 RESOURCES :

S.NO Name of the Equipment Quantity

1 Spot welding machine 1

2 GI Sheet of 75 x 50 mm 2

7.3 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.

7.4 THEORY: In resistance welding (RW) a low voltage (typically IV) and very high current

(typically 15,000 A) is passed through the joint for a very short time

(typically 0.25 s).This high amperage heats the joint, due to the contact

resistance of the joint and melts it.The pressure on the joint is continuously

maintained and the metal fuses together underthis pressure. The heat

generated in resistance welding can be expressed as

H = k i2 R t

Where H = the total heat generated in the work, J

i = electric current, A

t = time for which the electric current is passing through the joint, s

r = the resistance of the joint, ohms

and

k = a constant to account for the heat losses from the welded joint.

The resistance of the joint, R is a complex factor to know because it is

composed of

i. The resistance of the electrodes,

ii. The contact resistance between the electrode and the work piece,

iii. The contact resistance between the two work piece plates,

iv. The resistance of the work piece plates.

The amount of heat released is directly proportional to the resistance. It is

likely to be released at all of the above-mentioned points, but the only place

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where a largeamount of heat is to be generated to have an effective fusion is

at the interface betweenthe two work piece plates. Therefore, the rest of the

component resistances should be made as small as possible, since the heat

released at those places would not aid in thewelding.

Because of the squaring in the above, equation, the current, i needs to be

precisely controlled for any proper joint. The main requirement of the process

is the low voltageand high current power supply. This is obtained by means

of a step down transformerwith a provision to have different tappings on the

primary side, as required for differentmaterials. The secondary windings are

connected to the electrodes which are made ofcopper to reduce their

electrical resistance. The time of the electric supply needs to be

closely controlled so that the heat released is just enough to melt the joint

and the subsequent fusion takes place due to the force (forge welding) on

the joint. The forcerequired can be provided either mechanically,

hydraulically or pneumatically. Toprecisely control the time, sophisticated

electronic timers are available.

The critical variable in a resistance welding process is the contact resistance

between the two work piece plates and their resistances themselves. The

contact resistance is affected by the surface finish on the plates, since the

rougher surfaceshave higher contact resistance. The contact resistance also

will be affected by thecleanliness of the surface. Oxides or other

contaminants if present should be removedbefore attempting resistance

welding.

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7.5 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.

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7.6 DIAGRAM:

7.7 RESULT :prepared a lap Joint on the given work pieces using spot welding

equipment

7.8. POST LAB 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………………

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EXPERIMENT-8 PREPARATION OF BUTT WELDING USING TUNGSTEN

INERT GAS (TIG) WELDING 8.1 OBJECTIVE : To prepare a V – Butt Joint Using TIG Welding.

8.2 RESOURCES : MS flat 50 x 60 X 10 mm3,Tong, Chipping Hammer, goggles,

Tungsten Electrode, Ceramic Nozzle and Filler rod,Argon gas cylinder.

8.3 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, carbon dioxide 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 specific advantages. 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.

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A typical TIG welding setup is shown in fig.

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.

8.4 PROCEDURE:

Prepare the edges of the work pieces to be joined to the required V shape.

Finish the edges using emery paper.

Place the work pieces on the work table in the required position.

Set the current of the machine to 100 A.

Fix the tungsten electrode to the electrode holder.

Required size of the nozzle is selected and it is fixed to the torch.

Adjust the inert gas flow rate to the required rate.

Select the filler rod (same as base metals) of required diameter.

Touch the electrode to the work, so that current flow will be established and

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

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First tack weld is done on the work pieces.

Move the electrode slowly along the length of the joint with the filler rod, so

that the filler metal will be deposited in the joint.Repeat the operation for the second pass, so that required amount of filler metal will be deposited on the work pieces.

8.5 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.

8.6 RESULT:Prepared a V – Butt Joint Using TIG Welding for given MS sheets

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EXPERIMENT-9 PREPARATION OF BUTT WELDING USING PLASMA

WELDING 9.1 OBJECTIVE :To prepare BUTT joint using Plasma welding

9.2 RESOURCES :

S.NO Name of the Equipment Quantity

1 Scale 1

2 Scriber 1

3 Hand hack saw 1

4 Flat file 1

5 Swing scale protector 1

6 Welding machine 1

7 gloves, 1

8 Shield 1

9 Wire brush 1

10 Chipping hammer 1

11 Weld rod 1

9.3.PRECAUTIONS:

1. Wear apron,shoes,nosemask,glovesand tight fitted clothes.Becarefuland

attentive while working on welding job.

2. During welding don‟tsee the welding light rage directly without the gaggle

faceshield.

3. Donotcoolthewelding piece in water.

4. Donotkeep electrode holder onthe welding machine.

5. No inflammable material should be presentin welding shop.

9.4 PROCEDURE:

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

groove is formed)

2. Electrode is fixed to electrode holder.

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3. Connections to be given such that electrode- and work .Welding is to be done

carefully for the half-length of the plates.

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

5. The beadsare polished, etched with two percentnatal solution and studied

under themicroscope whose magnification factors 10X forthe heat effected

zone.

6. By gripping the beads b/w the jaws Tensiletesting machine and load is

applied until the work piece breaks and the readings is to be noted.

7. The same procedure is repeated for theremaining half which is welded by

reverse polarity and the results are to be compared.

9.5 DIAGRAM:

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9.6.RESULTS :

Prepared Joints for welding suitable for butt- welding by using Plasma welding

equipment.

9.7 POST LAB QUESTIONS :

1. What are the basic requirements of welding?

2. Explain the classification of welding processes.

3. What are the different types of welded joints?

4. Write about design of welded joints.

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EXPERIMENT-10 PREPARATION OF BUTT JOINT USING

OXY-ACETYLENE BRAZING PROCESS 10.1 OBJECTIVE:To join twosheets byusing oxy-acetylene brazing processbrazing

process

10.2 RESOURCES :

S.NO Name of the Equipment Quantity

1 Oxy-acetylene torch 1

2 filler rod 1

3 GI sheets

150x150x1mm 1

4 Wire brush 1

5 Hand gloves 1

6 Chipping hammer 1

7 Spark lighter 1

10.3 PRECAUTIONS:

1. As the filler metal fills the joint bycapillaryaction, give onlyneeded clearance.

2. Seethat the joints are extremelyclean.

10.4 DESCRIPTION:

1. Brazingis coalescence of a joint with the help of a filler metal

whosemeltingtemperature is 4500Cand is below solidifytemperatureof

thebasemetal. Thefiller metal is drawn intothe jointbymeans ofcapillary

action.

2. Brazingisametal-

joiningprocesswherebyafillermetalisheatedabovemeltingpointanddistributed

betweentwoormoreclose-

fittingpartsbycapillaryaction.Thefillermetalisbroughtslightlyaboveits

melting(liquidus)temperaturewhileprotectedbyasuitableatmosphere,usuallyafl

ux.Itthenflowsover

thebasemetal(knownaswetting)andisthencooledtojointheworkpiecestogether.I

tissimilartosoldering,except the temperatures used to melt the filler metal

arehigher.

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10.5 DIAGRAM:

10.6 PRCEDURE:

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. Jointis to be heated byusingweldingtorch to heat the filler metal to

itsmeltingtemperaturewhen the filler material is placedat the joint.

5. Thefillermaterial is flown into the servicebycapillaryaction and joint is made

10.7 RESULTS:Two sheets are joined using oxy-acetylene brazing process brazing

process

10.8 POST LAB QUSTIONS:

1. Different between welding , soldering and brazing

2. How Brazing works

3. What is Flux

36

EXPERIMENTS-11HYDRAULICPRESSWORKS-ROD BENDING

11.1 OBJECTIVES: To make rod bending usingHydraulic press

11.2 RESOURCES:

s.no

Name of the

Equipment Quantity

1 Hydraulic Press 1

2 MS rod 1

11.3. PRECAUTIONS:

1. Do not apply too high injection pressure

2. Proper lubrication must be done between moving parts

3. Operate the hydraulic press carefully.

11.4 THEORY:

BENDING:

Bending is the metal working process by which a straight length is

transformed in to the curved length. It is a very common forming process for

changing sheet and plate into channels, drums, 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 decrease in the

radius of curvature. The stretching of the bend causes the neutral axis of the

section towards the inner surface. In most cases the distance of the neutral axis

to the inside of the bend is 0.3t - 0.5t where t is the thickness of the part.

Bending terminology is illustrated in fig.

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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.

11.5 PROCEDURE:

1. Setthe bendingdie in the required position.

2. Switch on the motor to start the machine.

3. Pass the MS rod in to the die

4. Applyinjection pressureusingdirectioncontrolvalve.

5. Releaseinjection pressure.

6. Takeout the finished product from the die.

11.6 RESULT:

Rod bending is prepared using correspondingdie with hydraulicpress.

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11.7 POST LAB QUESTIONS:

1. what is blanking

2. what is piercing

3. what is a compound tool

EXPERIMENTS-12 HYDRAULIC PRESSWORKS –DEEP DRAWING 12.1 OBJECTIVE: To determine drawing force and blank holding force for

producing a symmetrical cup of circular cross section using a Draw Tool and

Perform Drawing Operation on hydraulic press.

12.2 RESOURCES : MS sheet of 0.3mm thickness and 110mm diameter,

Hydraulic Press, Draw die. 12.3 THEORY:

DRAWING:

Drawing operation is the process of forming a flat piece of material into a hollow

shape by means of a punch which causes the blank to flow into the die cavity. The

depth of draw may be shallow, moderate or deep. If the depth of the formed cup is

up to half of its diameter, the process is called “Shallow drawing”. If the depth of

the formed cup exceeds the diameter it is termed as "Deep drawing". Parts of

various geometries and sizes are made by drawing operation, two extreme

examples being bottle caps and automobile panels.

As the drawing progress i.e. as the punch forces the blank into die cavity, the blank

diameter decreases and causes the blank to become thicker at its outer portions.

This is due to the circumferential compressive stress to which the material element

in the outer portions is subjected. If this stress becomes excessive the outer

portions of the blank will have the tendency to buckle or wrinkle. To avoid this, a

pressure pad or blank holder is provided. The holding down of pressure is obtained

by means of springs, rubber pad, compressed air cylinder or the auxiliary ram on a

double action press.

39

The portion of the blank between the die wall and punch is subjected to nearly

purely tension and tends to stretch and becomes thinner. The portion of the formed

cup which wraps around the punch radius is under tension in the presence of

bending. This part becomes the thinnest portion of the cup. This action is termed as

'necking' and in the presence of unsatisfactory drawing operation, is usually the

first place to fracture. The outer portions of the blank under the blank holder

become thicker during the operation. When these portions are drawn into the die

cavity, 'ironing' of this section will occur if the clearance between the punch die is

not enough to accommodate this increased thickness of the work piece. This ironing

is useful if uniform thickness of the product is desired after the drawing operation.

Drawing Force:

The drawing force depends on the cup material, its dimensions and the configuration. The drawing force can empirically be calculated using the following

equation for cylindrical shells.

h = height of the shell, mm

d = outer diameter of the shell, mm

40

D = blank diameter, mm P = drawing force, N

t = thickness of the blank material, mm s = yield strength of the metal, Mpa

C = constant to cover friction and bending. Its value is between 0.6 and 0.7

Blank Holding Force:

The blank holding pressure required depends on the wrinkling tendency of the cup,

which is difficult to determine and hence it is obtained more by trail and error. The

maximum limit is generally one-third of the drawing force

12.4 OBSERVATIONS AND CALCULATIONS:

2. Drawing Force = N

3. Blank Holding Force = N

12.5 PROCEDURE

1. Drawing Operation: 2. Fix the punch to the ram of the press. 3. Fix the die on the bed of the machine using clamps, bolts and nuts.

4. Calculate the required blank size and place the same between the punch and die block.

5. Apply the hydraulic pressure on the punch through ram so that the punch slowly descends on the blank and forces it take the cup shape formed by the end of the punch, by the it reaches the bottom of the die.

6. When the cup reaches the counter bored portion of the die, the top edge of the cup formed around the punch expands slightly due to spring back.

7. Observe the reading of the pressure gauge which directly gives the force required to perform th operation.

8. Calculate the drawing force required, to perform the operation using above

relations. 9. Compare the two readings

10.Then move the punch in the return direction so that the cup will be 11.stripped by counter bored portion.

12.6 PRECAUTIONS:

a. The die should be properly clamped to the bed of the machine

and it is not disturbed during the process.

b. The punch is properly fixed to the ram of the machine.

41

c. The load should be applied uniformly on the bar.

d. The bar should be held properly on the die block.

12.7 RESULT:Deep drawing ofsymmetrical cup of circular cross section is done.

2. Drawing Force = N

. Blank Holding Force = N

EXPERIMENTS-13PREPARATION OF ALUMINIUM WASHER BY USING

FLY WHEEL PRESS

13.1 OBJECTIVE: To make Al washer using Fly wheel press

13.2 RESOURCES:

s.no Name of the Equipment Quantity

1 Fly wheel Press 1

2 Al sheet 1

13.3. PRECAUTIONS:

1. Do not apply too high pressure

2. Proper lubrication must be done between moving parts of die and press

3. Operate the fly wheel press carefully.

13.4 THEORY:

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.

42

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. 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.

13.5 DIAGRAM:

43

13.6 PROCEDURE:

1. Setthe blanking, piercing die in the required position.

2. start the machine.

3. Pass the Al sheet in to the die

4. Applyfly wheel pressure

5. Theplungerpunches the sheet into the washerlid shape.

6. Release pressure.

7. Takeout the finished product from the die.

13.7 RESULT:

Al washer is prepared using corresponding DIe in Fly wheelpress.

13.8: POST LAB QUSTIONS:

1. What is a compound die

2. what is a advance

3. what is a progressive die

44

EXPERIMENT-14 PROCESSING OF PLASTICS-INJECTION MOULDING

14.1 OBJECTIVE: To make an air tight bottle cap by using injection moulding.

14.2 RESOURCES: Die, injection-mouldingequipment,Plastic pellets

14.3 THEORY: Plastics:

Polymers can be divided into three broad divisions: plastics, fibers and

elastomers (polymers of high elasticity, for example, rubber). Synthetic

resins are usually referred to as plastics. Plastics derive their name from the

fact that in a certain phase of their manufacture they are present in a plastic

stage (that is acquire plasticity), which makes it possible to impart any

desired shape to the product. Plastics fall into a category known chemically

as high polymers.

Thus Plastics is a term applied to compositions consisting of a mixture

of high molecular compounds (synthetic polymers) and fillers, plasticizers,

stains and pigments, lubricating and other substances. Some of the plastics

contain nothing but resin (for instance, polyethylene, polystyrene).

Types of Plastics:

Plastics are classified on the broad basis of whether heat causes them to

set( thermosetting) or causes them to soften and melt(thermoplastic).

45

Thermosetting Plastics: These plastics undergo a number of chemical

changes onheating and cure to infusible and practically insoluble articles.

The chemical change is not reversible. Thermosetting plastics do not soften

on reheating and cannot be reworked. They rather become harder due to

completion of any left over polymerization reaction. Eventually at high

temperatures, the useful properties of the plastics get destroyed. This is

called degradation. The commonest thermosetting plastics are: alkyds,

epoxides, melamines, polyesters, phenolics and ureas.

Thermoplastic Plastics: These plastics soften under heat, harden on

cooling, and can beresoftened under heat. Thus they retain their fusibility,

solubility and capability of being repeatedly shaped. The mechanical

properties of these plastics are rather sensitive to temperature and to

sunlight and exposure to temperature may cause thermal degradation.

Common thermoplastics are: acrylics, poly tetra fluoro ethylene (PTFE),

polyvinyl chlorides (PVC), nylons, polyethylene, polypropylene etc.

Injection Moulding: An important industrial method of producing articles of thermoplastics is

Injection Mouilding (shown in fig.). The process is essentially as follows

The moulding material is loaded into a hopper from which it is

transferred to a heating section by a feeding device, where the temperature

is raised to 1500C – 3700C and pressure is built up. The material melts and

is forced by an injection ram at high pressure through a nozzle and sprue

into a closed mould which forms the part. The mould is in at least two

sections, so that it may be split in order to eject the finished component. For

the process to be competitive the mould must be fairly cool (between

ambient temperature and the softening point of the plastic) and

consequently the mould must be cooled by circulating air

46

14.4 PROCEDURE:

1. The pellet form of plastic is introduced into the container through hopper.

2. The plastic pellet enters into the container. The container is heated

with the coil, which is wounded around it.

3. The plastic of powder form is converted into molten stage at a

temperature of 800C.

4. The die is placed exactly below the nozzle of the container.

5. The melted plastic is injected into the die with the help of lever arm

and it is allowed to solidify say for about one minute.

6. Then retract the lever arm slightly and open the mould. 7. Then eject the mould piece of the required shape from the die.

47

14.5 PRECAUTIONS:

1. The material should not be heated rapidly.

2. The die should be placed exactly below the nozzle.

3. Proper temperature should be maintained while heating the plastic.

14.6 RESULT: Air tight bottle cap is prepared by using injection moulding.

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EXPERIMENT-15 PROCESSING OF PLASTICS- BLOW MOULDING

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

15.2 RESOURCES : Blow moulding machine,Low grade poly ethylene

15.3 THEORY:

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

49

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.

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.

50

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 and check for smooth functioning of plunger.

10.Set the blow pressure in regulator and operate the hand lever valve 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.Properearthing 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.

51

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 next cycle.

RESULT: Required product is made using blow molding process.

1. PVC stands for ___________.

2. Injection moulding is similar to ___________ casting.

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

4. Thermoplastic materials are produced by ____________ process

5. Plastics are bad conductor of ___ and _______