Aircraft Material & Production -MANUAL

8/13/2019 Aircraft Material & Production -MANUAL

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CONTENTS

S.NO. DESCRIPTION

1 THE LATHE1-A LATHE OPERATIONS

2 DRILLING

2-A DRILLING OPERATIONS

3 SHAPING

3-A SHAPING OPERATIONS

4 MILLING & GEAR CUTTING

4-A MILLING OPERATIOINS

5-A GEAR CUTTING OPERATIONS

5-B V- GROOVE & ANGLE CUTTING IN MILLING

6 GRINIDING

6-A SURFACE GRINDING

6-B SURFACE GRINDING OPERATIONS

7 ELECTRICAL DISCHARGE MACHINE ( EDM )

7-A DRILLING A HOLE WITH EDM

8SHEET METAL JOINING BY RIVETS, SOLDERING ANDBRAZING

8-A SHEET METAL JOINING BY RIVETS

9 COMPUTER NUMERICAL CONTROL (CNC)

9-AGENERATION OF COMPUTER NUMERICAL CONTROL(CNC) PROGRAM

10 WELDING

10-A WELDING OPERATIONS

11 METAL JOINING PROCESSSES - SOLDERING

11-A BRAZING

MATERIALS LAB

12 WOOD GLOOVING PRACTICE13 STUDY OF PROPERTIES OF SANDWICH STRUCTURES

14STUDY OF MICROSTRUCTURES OF NONFERROUSMETALS

15 AUTOCLAVE FOR DIFFERENT GEOMETRICAL STRUCTURES


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SYLLABUS

AIR CRAFT MATERIALS AND PRODUCTION LAB

JNTUH - HYD.

II Year B.Tech. A.E.-II Semester. T P C

0 3 2

Production Lab;-

1. Plain turning, Taper turning, Facing. Knurling. Thread cutting.

2. Drilling. Boring. Counter boring. Counter sinking.

3. Shaping and planning of square block, V- ways and Dovetail ways.

4. Plain Milling.

5. Gear Milling (step milling & slot milling)

6. Cylindrical grinding / Surface grinding

7. Simple exercises in EDM

8. Sheet metal joining by rivets, soldering and brazing

9. Simple exercises on CNC machines and programmer generation.

10. Simple exercises in solid state welding, Gas welding & arc welding

11. Metal joining techniques (soldering and brazing).

Materials Lab:

12. Aircraft wood gluing practice.

13. study of properties of sandwich structures

14. Study of microstructures of non ferrous alloys.

15. experiment on autoclave for different geometrical structures

REFERENCE:

1.Aircraft production techniques keshu S.C, Ganapathy K.K Interline PublishinghouseBangalore 1993.

2. Manufacturing Engineering and technology by Kalpakajam-Addison Wesley.


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1. THE LATHE

Function:- The function of a lathe is to remove excess material in the form of chips byrotating the work Piece against a cutting tool to produce cylindrical shapes. The toolmaterial should be harder than the work piece. The tool may be given liner motion along

work piece in any direction.

Size (or) specification of lathe:-

1. The height of the centers measured form the lathe bed.

2. The swing diameter over bed.3. Maximum job length held between the two centers.

4. The swing diameter over carriage.

Types of lathes:-

1. Bench Lathe. 2. Speed Lathe. 3. Engine Lathe. 4. Tool Room Lathe.5. Capstan and turret Lathe. 6. Automatic Lathe.

Parts of Lathe:-

1. Base or Bed. 2. Head stock. 3. Tail stock. 4. Carriage. 5, Cross Slide.

6. Compound rest. 7. Apron. 8. Lead Screw. 9. Tool Post.

Lathe operations:-S.NO. Sequence of operation Cutting tool.

1. Facing Facing H.S.S.Single point tool

2. Plain Turning H.S.S.Single point tool

3. Step& Under cut. Single point tool / Parting tool.

4. Taper Turning. H.S.S.Single point tool

5. Knurling. Knurling Tool.

6. Chamfering H.S.S.Single point tool

7. Thread cutting V- Thread cutting tool.


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LATHE MACHINE PARTS

Facing:- Facing is the operation of machining the end of a piece of work to produce flatsurface With axis. This is also used to cut the work to the required length. The operationinvolves Feeding the tool perpendicular to the axes of rotation of work piece.

Plain Turning:- The plain turning operation requires high cutting speed, small feed and a

very small depth of cut to generate a smooth surface. copious supply of coolant andlubrication should be used to produce a smooth finish.

Step& under cut:-Step Turning is the operation of making different diameters of desiredlength. Under cut is the operation of making a slot over the periphery of a circular job.

Taper Turning:-Taper turning may be defined as a uniform increase or decrease indiameters of a piece of work, measured along its length. In a lathe , taper turning meansto Produce a conical surface by gradual reduction in diameter from a cylindricalwork piece.

Tan =D-d / 2L

D= large diameter of taper in mm.

d = small diameter of taper in mm

L = Length of tapered part in mm.

2= full taper angle. = half taper angle.

Methods of tapers:- Setting over the tail stock centre.

By swiveling the compound rest.

By a taper turning attachment.

By combining longitudinal and cross feed in a special lathe.

By forming tool method.

Chamfering:- It is the operation of beveling the extreme end of the work piece. This is


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done to remove burrs, to protect the end of the work piece from being damaged and tohave a better look.

Knurling:- Knurling is the process of embossing a diamond shaped pattern on thesurface of a work piece. The purpose of knurling is to provide an effective grippingsurface on a work piece to prevent it from slipping when operated by hand.

Thread cutting:- Thread cutting is one of the important operation performed on a lathe.Both and External and internal threads can be cut. There should be a certain relation

between job revolution and revolution of lead screw to control liner movement engagedwith the screw. The tool should be grounded to a proper shape on profile of thread to becut. In all modern lathe quick change gear box is provided with different ratios of spindleand lead screw revolution can be easely obtained by simply shifting the change gearlever. The longitudinal feed should be equal to the pitch of the thread to be cut perrevolution of the work piece.

Pitch of the threads to be cut

Velocity ratio = -----------------------------------

Pitch of the lead screw.

But velocity ratio = (Driver teeth / Driven teeth.)

Metal Cutting Parameters ;-

Cutting speed:- The cutting speed (V) of a tool is the speed at which the metal isremoved by the tool from the work piece. In a lathe it is the peripheral speed of the workpast the cutting tool expressed in meters / min.

V= d n / 1000

Where,

d the diameter of the work in mm.n The rpm of the work.

Feed:- The feed of a cutting tool in a lathe work is the distance the tool advances for

each revolution of the work. Feed is expressed in terms of mm / revolutions.

Depth of cut:- The depth of cut is the perpendicular distance measured machinedsurface tothe uncut surface of the work piece. In a lathe the depth of cut is expressed asfollows.

Depth of cut = d1- d 2/ 2


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1[A]. LATHE OPERATIONS

Aim:- To perform various lathe operations such as Facing, Plain turning, Stepturning. Taper turning, Under cut, Knurling , Thread cutting and

Chamfering.on a given material made of mild steel.

Material Required:- A mild steel bar of 25mm diameter and 100mm long.

Tools used;- H.S.S. single point cutting tool, parting tool, V-tool for threading , Knurlingtool, Chuck key, tool post key.

Measuring instruments:- out side caliper, steel rule, pitch gage etc.

Procedure:-

1. Set the work piece on the chuck and tool on the tool post.

2. Operations such as facing& plain turning are performed on a given M.S. bar.Then the step & under cut turning is performed using parting tool. (Final cut).One after another in the sequence upon the dimensions as shown.

3. Now the compound rest is swiveled by calculated half taper angle and taper isgenerated on the work piece, by rotating the compound slide screen willcause the tool to be feed at the half taper angle ().

4. H.S.S. tool is replaced by Knurling tool in tool post. Knurling generation isperformed at the slowest speed of the spindle.

5. Knurling must be done at low speed available and apply lubricating oil whileknurling.

6. H.S.S. V- Shape thread curing tool fix the tool post and set the work piece onthe chuck.

7. The change gears of correct size are calculated and then fitted to the end ofthe bed between the spindle and the lead screw.

8. The top of the tool nose should be set at the same height as the center of thejob.

9. Thread cutting generation is performed at the slowest speed of the spindle.

10. Engage the lead screw lever and start the operation. Apply proper coolantduring cutting point.

11. The depth of cut usually varies from 0.05mm to 0.2mm.

Precautions;:- Operate the machine at specific speed.

Do not depth of cut more than 2mm.

Apply lubricating oil while all operations

Make sure that the work place is neat and clean.

Result:- The required operations are successively completed.


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2. DRILLING

Introduction: - Drilling is a process of making a hole in an object by forcing a rotating toolcalled drill. The same operation can be performed in a lathe by holding the drillstationary and rotating work.

RADIAL DRILLING MACHINE

Types of drilling machines:-1. Portable drilling m/c.,2. Sensitive drilling m/c. 3Gangdrilling m/c. 4. Radial drilling m/c. 5. Automatic drilling m/c. Etc.

Radial drilling machine:- It is intended for drilling small and large holes on a heavy work

piece. This consists of a heavy round vertical column, mounted on a large base. Thecolumn supports a radial arm which can be raised and lowered to accommodate workpiece of different heights. The arm may be swung around to any position over work bed.The three movements in radial drilling machines when combined together permit to belocated at any desired point on a large work piece for drilling.

Parts of a drilling m/c.:- Base, column, Radical arm, Elevating screw, Drill head, Drillspindle, Table, Motor for elevating the arm, Motor for driving spindle.

PARTS OF A DRILLING MACHINE


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Spindle Drive and Feed Mechanism:- There are two common methods of driving aspindle.

a) Contact speed motor is mounted at extreme end of radialarm.

b) Train of gearing within the drill head

S.NO. Sequence of operation Tool used1. Marking Vernier height gauge, Surfaceplate.

2. Punching Dot punch, hammer.

3. Pilot-holed drill Drill bit.

4. Drilling Drill bit.

5. Reaming Reamer

6. Boring Boring tool.

7.Counter Boring Counter bore drill.

8. Counter Sinking Counter Sink drill

Marking:- Before drilling any hole on the given work piece, the center of the hole islocated by drawing two lines at angles to each by means of venire height gauge placedon surface plate.

Punching:- After locating a center, identification is made at the point where the hole isto be drilled. Pinching is done by means of center punch and ball peen hammer

Pilot-holed drill: Before drilling a hole of a larger diameter, a pilot hole of 3mm which isslightly Grater then the width of the chisel edge must be drilled. The reason is that the

action of the chisel edge during drilling is more or less an extrusion process. So 80 to85% of total thrust, i.e., vertically upward force will come on chisel edge which increasesthe power required and decreases the tool life. This refers to eliminate the thrust actingon the chisel edge pilot hole is made prior to drilling.

Drilling:- It is the operation of producing a cylindrical hole by removing metal by therotating edge of a cutting tool called the drill. The drilling is the one of the simplestmethods of producing a hole. Drilling does not produce an accurate hole.

Reaming:- It is an aureate away of sizing and finishing a hole which has been alreadydrilled. In order to finish a hole and bring it to the accurate size. The hole reamer ismade half that of drilling and used for reaming is known as reamer, which has multiple

cutting edges, reamer can not originate a hole, its simply follows the path, which hasbeen previously drilled and removes small amount of metal, the materiel removed bythis process is around 0.395mm and for the accurate work, this should not exceed0.125mm.

Boring:- To enlarge a hole by means of an adjustable cutting tool with only onecutting edge, this is necessary where suitable sized drilled is not available or wholediameter is so large that it can be ordinary drilled. To finish a hole accurately and tobring it tothe required size. To machine the internal surface of the hole alreadyproducing. To correct all of roundness of the hole. To correct the location of hole as beboring tool follows as independent path with respect to the hole.

Counter Boring:- The enlarged hole forms a square shoulder with the original hole.This is necessary is some cases to accommodate the heads of bolts, studs and pins.The tool used for this is called counter bore. The counter bores are made with straight ortapered shank to fit in the drills spindle. Counter boring can give accurately of about


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0.005mm. The cutting speed for counter boring is 25% less than thatof drillingoperations.

Counter Sinking:- It is the operation of making a cone shaped enlargement of the end ofa hole to Provide a recess of a flat head screw or counter sink rivet fillet in the hole. TheTool used for counter sinking is called counter sink standard counter sinkers have 600 ,

820and 900 inclined angle that the cutting edges of tool are formed at the conicalsurface. The cutting speed in counter sinking is 25% less than that of drilling.

Drill Chucks:- A drill chuck is a device intended for holding smaller size drills. It hastwo or more adjustable jaws set radially to hold straight shank drills. It is provided with ataper shank which is fitted in the tapered hole of the spindle. These are made invarious sizes.

Twist Drills:- It is an end cutting tool. It is the most common type of tool used in drilling. Itconsists of a cylindrical piece of steel with special grooves called flutes

Typestwist drills: - 1) Parallel shank twist drill. 2) Taper shank twist drill.

Drills materials: - Cutting portion---- High speed steel

Shank portion. ----Carbon steel.

Cutting speed: - It is a measure of peripheral speed of the drill in operation expressed inm/min.

Cutting speed (S) = D N / 1000 m/min.

D is the diameter of the drill in mm

N is the r.p.m of the drill spindle.

Feed = the feed of a drill is the distances the drill moves into the work at eachrevolution of the spindle. It is expressed in mm/ revolution or per min

The feed for min. = Feed per revolution X rpm

Depth of cut = the depth of cut in drilling is equal to one half of the drilldiameter.


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2[A].DRILLING OPERATIONS

AIM:- To perform Drilling. Reaming, Boring, Counter boring, Counter sinking, andtapping.

TOOLS;- Drill bits, Reamer, Boring tool, Counter bore drillbit, Counter sink drillbit, Tap setWith wrench, Vernier height gauges, surface plate, Dot punch Hammer. Etc.

Material:- Mild steel flat piece.

Procedure:- 1) Before drilling holes, center of holes are located on a work piece bydrawing Two lines at right angles to each other using vernier height gauge and surfaceplate.

2) Punching is done using center punch and ball peen hammer at thelocated centers.

3) Work piece is firmly fixed in the vice on a drilling machine table anddrill bit is firmly fixed by drill chuck.

4) The pilot holes are drilled at the chosen location by starting thedrilling at the drilling machines.

5) Drill is replaced by actual size drill and required holes are made inpreviously drilled pilot holes.

6) The adjustable boring tool held in a boring bar replaces drill bit andthe first hole is enlarged to final size.

7) Boring tool is replaced by the reamed and the subsequent sizing andfinishing of the reaming a hole is done by performing reaming operation by giving hand

feed.8) Reaming is replaced by the counter bore with pilot to enlarge, to

form a square shoulder with the original hole.

9) Counter bore is replaced by the counter sink for given diameter and900inclined angles to the end of hole and enlarged conically.

10) Tapping is done using hand tap set, by a tap hole.

Precautions:- 1. The drill bit must be properly fixed,2. Centers must be correctly marked.3. Slightly lower speeds of the order of 25% less than drilling should be

used to counter boring, counter sinking operations.

4. Holes of larger diameter should never be drilled without a pilot hole.5. Apply proper coolant during drilling operation.Result:- The required operations are successively completed.


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PARTS OF A SHAPER

Parts of the shaper:

1. Base. 2. Column 3. Cross slide 4, saddle 5. Table 6. Clapper box

7. Ram 8. Tool head. 9. Feed disc. Elevating screw. etc..

Driving mechanisms:

1) Crank an slotted lever mechanism2) whit-worth quick return mechanism

3) Hydraulic shaper mechanism

Shaper operations:

1. Horizontal machining 4. Slots, grooves and key ways cutting

2. Vertical machining 5. Cutting gears or splines.

3. Angular machining

Cutting sped:- In a shaper the cutting action is intermittent and is considered only duringthe forward cutting stroke.

Length of cutting stroke.Cutting sped:- --------------------------------------------

Time required by the cutting stroke.

Feed:- It is the relative movement of the tool or work in a direction perpendicular tothe axis of reciprocation of the ram for double stroke. In is expressed inmm. The feed is always

given at the end of return stroke when the tool is not cutting the metal.

Depth of cut:- It is the thickness of metal that is removed in one cut. It is theperpendicular distances measured between machined surface and nonmachined surface of the work piece.


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3[A].SHAPING OPERATIONS

AIM:- Shaping of square block, V- groove.

All dimensions are in mm

tolerances0.05mm

Tools:- side tool, V- tool, try square, vernier caliper, steel rule

Materiel;- m.s. square block

Procedure: 1 .The job is fixed on a vice.

2 The tool is fixed on tool post.

3. The stroke of ram is adjusted to required length and machine is switchedon.

4. Always during machining the job should be properly fixed with the half oftry squareand vice to get a right angle surface after machining.

5 After completion of work, the job should be filled help of file.

6. Before fixing the job, V block dimensions are marked on the job with thehelp of dot punch.

7. The tool head should be rotated at 450to make the V- groove.

8.The feed is given such that the tool moves gradeavelly on either side of themiddle line.

9. The tool is moved to get the required groove.Precautions:- 1. The tool should be properly fixed.

2. Proper movement of tool must be entered.

3. Select proper cutting speeds.

4. Dont touch and measure the job during the process of machining.

Result:- The given square block is machined for plain shaping and done by V grooveas for given dimensions.


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4. MILLING

Introduction:- Milling is a machining process in which metal is removed by rotatingmulti-edge cutting tool called milling cutter, while the work piece fed against to it. Amilling machine is a machine tool that removes metal chips. Work is fed against arotation multipoint cutter. It removes metal at a very fast rate. The job movement ishorizontal, vertical and cross feeding.

GENERAL MILLING MACHINES

Types of milling m/c.:- Column and knee type.

1. Horizontal milling. 2. Vertical milling. 3. Universal milling.

4. Omniversal milling.

Parts of milling m/c:-

1. Base. 2. Column. 3. Knee. 4. Saddle. 5. Table. 6. Spindle. 7.Arbor. 8. Elevating screw. 9. Overhanging arm. Etc.

Milling m/c. mechanism:-

The spindle drive mechanism is incorporated in the column. Allmodern machines are driven by individual motors housed within thecolumn, and the spindle reeves power from a combination of gears

and clutch assembly. Multiple speeds of the spindly may be obtainedby altering the gear ratio.

Work holding devices:- T- bolts and clamps, V-blocks, Angle plate, Vices, etc.

Cutter holding devices:- Arbors, collets, Adapters, Spring collets, Bolted cutters,

Screw on cutters.

Standard milling cutters:-

Plain milling cutter. Side milling cutter, Angle milling cutter,

End milling cutters. T- Slot milling cutter. Fly cutter.

Formed cutters, (Convex, concave, corner rounding, gear cutter.)

Face milling cutter or T max cutter, Saw milling cutter.Types of milling processes:


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UP MILLING DOWN MILLING

MILLING METHODS

( a ) Up milling : The up milling which is also called conventional milling, is the processof removing the metal by a cutter which is rotated against the direction of travel of thework piece.

( b ) Down milling : The down milling which is also called climb milling, is the process ofremoving the metal by a cutter which is rotated in the same the direction of travel of thework piece.

Cutting speed:- The cutting speed of a milling cutter is its peripheral linear speedresulting from rotation. It is expressed in meters per minute. The cutting speed can bederived formula.

V= d n / 1000 minutes per min.V= the cutting speed in inch per min.

d= the diameter of the cutter in mm.

n= the cutter speed in rpm.

Feed:- The feed in a milling machine is defined as the rate with which the workpiece Advances under the cutter.

Depth of cut:- The depth of cut in milling is the thickness of the material moved in onepass of the work under the cutter.


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GEAR CUTTINGGear cutting methods:- toothed gears are indispensable elements in mechanicaltransmission of power, and their accurate production necessitated the development ofingenious tools and process. Gears made my be manufactured by casting, stamping,machining or by powder metallurgical processes. Out of all such process, the most, and

accurate method of production of gears is by machining.

SPUR GEARSSpur gear:- The cutting of spur gear in a milling machine involves the followingprocedure,

1. To determine the important dimensions and proportions of the gear toothelement.

2. To control the spacing of the gear teeth accurately on the periphery of thegear blank.

3. To select the correct number of cutter for the required number of teeth onthe gear.

4. To determine the proper speed of the cutter, fed of the table, and thedepth of cut.

5. To set the cutter and the work and to perform the actual operation.


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4[A]. MILLING OPERATIONS

Aim:- To machine a rectangular m.s. block to prepare plain milling, Step milling, andslot milling.

Tools required:- Vernier calipers, steel rule, scriber, dot punch, hammer, file.

Accessory in machine:- parallels, tri. Square, end milling cutter, plain milling cutter,

Material required:- M.S. block.( 75x75x 25mm3.)

Procedure:- 1. The job is fixed on the table vice.

2. The Face milling cutter is fixed on the arbor.

3. Cut the job by giving proper feed and cutting speed.

4. Always during machining the job should be properly fixed with the helpof try

square and vice to get a right angle surface after machining.

5. All sides machined the work, the job should be filled with a file.

6. Remove the face milling cutter, replaced by collets arbor fix the end millcutter.

7. Before fixing the job, the step & slotted dimensions are marked on thejob with the

help of dot punch and hammer.

8. Using end mill cutter or side milling cutter, the job is machined to thegiven

dimensions.

9. After completion of work, the job should be finished using triangular file.

Precautions: - The cutter should be properly fixed.

Select proper cutting speed, feed and depth of cut.

Apply proper coolant during machining.

Safety devices like goggles, apron and shoes must be wear.

Dont touch and measure the job during the process of machining.

Result:- The required operations are successively completed by given dimensions.


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5[A] GEAR CUTTING OPERATIONS

AIM: Study of spur gear cutting in Milling Machine

MATERIALS : MS ROUND dia 40 mm x 20 mm thickness

TOOLS REQUIRED : Gear tooth caliper, Gear cutter, Indexing head, Indexing plate, tailstock, mandrel, spanners

GEAR CUTTING SETUP IN MILLINGPROCEDURE:

Indexing: - It is the process to deviate the periphery or length of a job into required equalor

unequal no. of division.

Indexing head:- It is the attachment used to perform Indexing purpose.

Types of Indexing: -

1. Direct. 2. Indirect. 3. Deferent. 4. Compound. 5. Angular.

6. Linear. 7. Block indexing.

Direct indexing: - It is called rapid indexing. It is done on Direct Indexing head anduniversal

Indexing head.

No. of holes in indexing plate.

Indexing moment : ----------------------------------------------

N

I.M. = 32 = 2 spaces in 32

16

Indirect indexing: - Simple indexing or plain indexing


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As the shaft carrying the crank has a single thread worm to whichmeshes with the worm gear having 40 teeth, 40 turns of the crank are necessaryrotate the indexing head spindle through one revolution. Indexing plates with circle ofholes patented by the Brown and Sharpe company standard index plates.

Plate no. 1:-- 15, 16, 17, 18, 19, 20.

Plate no. 2:-- 21, 23, 27, 29, 31, 33.

Plate no. 3:-- 37, 39, 41, 43, 47, 49.

Example:- N=15.

No. of holes in indexing plate. 40

Indexing moment : ----------------------------------------- =-----------

N N

40 8 2 5 10

----- = --- = 2 --- x ---- = ----

15 3 3 5 15

I.M.= 2 complete circle of indexing crank and 10 spaces in 15 hole in a circleplate.

INVOLUTE GEAR CUTTER:

Cutter no. No. of teeth cut.

1 135 to to a rack.

2 55 to 134. Teeth.

3 35 to 54. Teeth.

4 26 to 34. Teeth.

5 21 to 25. Teeth.

6 17 to 20. Teeth.

7 14 to 16. Teeth.

8 12 to 13. Teeth.

GEAR

It is round and teeth on periphery. There are two goops.

1. Spur Teeth: - They are parallel to the axis.

2. Helical Teeth: -They are parallel to the at an angle to the axes. Soaccording to the Right and Left hand axis.

Types of gears:-

1. Spur gear. 2. Helical gear. 3. Bevel gear. 4. Hearing gear.

5. Rack& Pinion gear. 6. Worm and worm gear. 7. Internal gear.

Spur gear nomenclature.

Out side circle: - It is biggest circle. It is cut on lathe machine.

Pitch circle : - It is the imaginary circle. Which separates addendum anddedendum and on this circle. It is most important circle as all the calculations and designof tooth is based on this circle.

Clearance circle: - This is circle on which the out side circle of other gears touches.

Root circle: - It is circle do train by the milling cutter.

Bore circle: - It is circle of bore which is the shaft passes. It is obtain by lathe

machine.

Out side diameter: - It is the dia of the o.s circle.

Pitch diameter: - It is pitch diameter of the pitch circle.

Clearance diameter:-It is the dia of the clearance circle.


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Root dia: - It is the dia at the bottom of the tooth spaces.

Bore diameter: - It is the dia of the Bore circle.

Addendum: - It is the height from the pitch circle to tip of the tooth.

Dedendum: - It is the depth of tooth space below the pitch circle and equalsaddendum plus clearance.

Clearance: - It is the difference between the dedendum of one gear and the

addendum of the making gear.Cordial addendum:-This distance from the o.s. circle of the straight line drawn by joiningthe pitch point on the tooth.

Cordial Dedendum:-This is top surface.

Face: - It is the part of the tooth surface lying o.s. the pitch surface.(imaginaryrollers)

Flank: - It is that part of the tooth surface lying inside the pitch surface.

Circular pitch:- It is the length of the arc of the pitch circle between similar facesof

successive teeth.

Cordial pitch: - It is the distance measured in straight line from tooth along the pitchcircle.

Diameter pitch: - It is the number of teeth divided by the pitch diameter.

Depth of pitch: - No. of teeth per inch pitch dia.

Module: - It is the size of the tooth in mm.

Thickness of tooth: - It is the thickness of the tooth measured on the pitch circle. It is the

cordial thickness measured in straight line of pitchcircle.

SPUR GEAR GENERATION PRINCIPLE

SPUR GEAR FORMULA

1. Addendum:- lm (module) or ded- clearance.2. Dedendum:- Add + Clearance. or 1.25m.

3. Clearance:- 0.25m.

4. Working depth:- Add + dendclearance = lmx 1.25- .25 =2m.


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5. Total depth:- Add + dend. =2.25.

6. O.D.:- ( n+2)m

7. Pitch diameter:- m x n= mn. or (O.D. 2add.)P.D. O.D.- 2m

8. N (no. of teethes): ------- or ---------------

m m

9. Circular pitch: - 2 thickness ( m) m

10. Thickness of pitch:- ------ = 1.5708m

2 sin.90

11. Cordele thickness: ----------------------- P.D x ---------; P.D= O.D.2add.

PD cos. 90 N

12. Cordele addendum: ----- (1- ---------- ) + a

1 2 N

13.D.P. = ------------

Module 114. Module: ----------------- ------

D.P.

EXAMPLE:- M= 4. T. = 45.

40 40 8 3 24

Indexing = ------ = ----- = ----- x ----- = -----. 24 space in 27 O

N 45 9 3 27

O.D.= m (n+2) = 4(45 + 2) = 4 x 47 =188mm.

Total Depth:- 2.25 x m = 2.25 x 4 = 9.00 mm.

No. of cutter = 3. Module = 4. N. = 45.Thickness of tooth:- 1.5708 x 4 = 6.2832.

Sin.90

Chordal thickness: - P.D x ---------; (P.D. = O.D.2 add. ;), P. D. = 1888 =180mm.

N

Sin.90

C.T. = 180 x ---------- = 180 x sin.2: 180 x 0.0349 = 6.282

45

P.D. cos. 90 180Chordal addendum:- ------ (1 - -------- ) + 4. = ----- (10.9994) + 4. = 90 (.0006 ) +4.

2 N 2

= 0.054 + 4 = 4.054mm.

Result: The given block was machined as a spur gear successfully.


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5[B].V- GROOVE & ANGLE

Aim:- To machine a rectangular M.S.block and prepare V-groove and angle with given

dimensions.


tolerances0.05mm

Tools required:- vernier caliper, steel rule, scriber.

Accessories in machine:- parallel blocks, end mill cutter, plain milling cutter, spanner,

Material required:- 75 x 75 x25 mm. M.S.block.

Procedure:-

1. The job is fixed on the table vice.

2. The cutter is fixed on the arbor.

3. Before fixing the job, the stepper dimensions are marked on the job withthe

help of height gauge and dot punch.

4. Using end mill cutter or side milling cutter the job is machined to the

givendimensions.

5. After completion of work the job should be finished using the tri-angular

file.

Precautions:-

1. The cutter should be properly fixed.

2. Apply proper coolant during machining.

3. Select proper cutting speed.

4. Safety devices like goggles, apron and shoes must be wearing.

5. Dont touch and measure the job, during the process of machine.

Result: The given rectangular block is machined for V-groove and Angle with given

dimensions.


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6. CYLINDRICAL GRINDINGIntroduction:- Grinding is a metal cutting operation performed by means of a rotatingabrasive wheel that acts as a cutting tool. This is used to finish work pieces which mustshow a high surface quality, accuracy of shape and dimension. In grinding process,work piece is brought into contact with revolving grinding wheel. Each abrasive grain willact as an individual cutting tool and removes the metal in the form of small or tiny chips.Hence grinding wheel has a self- sharpening action.

CYLINDRICAL GRINDING CYLINDRICAL GRINDING LINE DIAGRAM

Types of grinding m/s;-1. Cylindrical grinders. a} Center type (plain & Universal). b)Center less.) 2. Surface grinder 3. Tool & cutter grinder.

Cylindrical Center type grinders:- Center type cylindrical grinders can be used forgrinding contoured cylinders, types, faces and shoulders, fillets, and even cams andcrankshafts.

Main features:- The work piece is usually held between dead centers and rotated by adog and driver on the faces plate. The work may also be rotated about its own axis in achuck. There are 4 types in a Cylindrical Center type grinder: 1.The work must

revolve, 2. The work must revolve. 3. The work must pass the wheel, 4. The work mustpass the work.

External cylindrical grinding:- This is produces a straight or tapered surface on a workpiece. The work piece must be rotated about its own axes between centers as it passeslengthwise across the face of a revolving grinding wheel.

Internal cylindrical grinding :- This is produces internal cylindrical holes and tapers. Thework pieces are chucked and precisely rotated about their own axes. The grinding wheelor, in the case of small bore holes, the cylinder wheel rotates against the sense ofrotation of the work piece.


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6[A]SURFACE GRINDINGSurface grinder:- Surface grinding m/cs, are machines that are employed to finish

plain or flat surfaces. But they are also capable of grinding irregular, curved, tapered,convex, and concave surface.

Parts of S.G:-1. Base, 2 columns. 3wheel head, 4 .Table, 5. Wheel, 6. Saddle 7. Magnettable.

Tool & cutter grinder: - Tool cuter grinders are used mainly to Sharpe and reconditionmultiple tooth citter like reamers, milling cutters, drills, taps, hobs and other types oftools used in shop. With various attachments they can also do like surface,cylindrical, and internal grinding to finch such items as jig, fisher, dies and gauge detailand sharpen single point tools.

Parts of T& C grinder:- 1. Base, 2 columns. 3wheel head, 4 .Table, 5. Wheel.( cup &shaped wheels) 5. Saddle.

The Grinding wheel:- It is a many hard particles known as abrasives. The abrasivesgrains are mixed with a suitable bond, which acts as a matrix or holder when the wheelis in use. Abrasives in two principal groups. 1. Natural abrasive, like as sandstone orsolid quartz, emery, corundum,, and diamond.

2. Artificial abrasives. Two types (A) Silicon carbide (Sic) abrasive.

(B) Aluminum oxide (Al2O3).


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6[B].SURFACE GRINDING OPERATIONSAim: - To perform surface grinding on a given work piece.


tolerances0.005mm

Tools required: - micro meter, oil stone, diamond dresser

Procedure:-

1. The given work piece has to be cleaned with emery sheet properly.

2. Keep the job on the magnetic table and switch on the magnetic lever.

3. Dress the grinding wheel properly for effective grinding.

4. Check and use the proper coolant in sufficient flow.

5. With a minimum of 0.5 mm feed operate the table smoothly and slowly andstart grinding operation for one side of the work piece.

6. Similar way repeat the same on all sides of the work piece.

Precautions:-

1. Use always proper coolant.

2. Depth of cut should be minimum.

3. Do not touch the running grinding and work piece when the machine is in running.

4. Use safety goggles.

Result: - The given work piece is grinded to the given dimensions.


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7. ELECTRICAL DISCHARGE MACHINING

Electrical Discharge Machining is a process where hard, tough, fragile andheat sensitive metals that are difficult or impossible to machine by conventionalprocesses can be worked.

WORKING PRINCIPLE:

Almost everyone is familiar with the sparking and arcing that takes place whenan electrical switch is turned on or off. Pitting or burning such as occurs on the switchcontacts, is the basis of electric discharge machining, Fig

An electrical discharge unit, fig is composed of a power supply to provide

direct current and a method to control voltage and frequency; an electrode of the properconfigurationthe electrode, usually yellow brass, can be compared with the cuttingtool in conventional machining; a servo mechanism to accurately control the movementof the electrode to maintain the correct distance between it and the work as machining isdone; a coolant, usually a light oil, that forms a dielectric barrier between the electrode,and the work at the arc gap.

The servomechanism maintains a very thin gas (about 0.001in.) between theelectrode and the work. These are submerged in a fluid (dielectric) that is a non-conductor. When the voltage across the gap reaches a point sufficient to causedielectric to break down, an arc occurs. Each spark erodes a minute piece of metal, butas the sparking occurs 20,000 to 30,000 times per second, appreciable quantities of

metal are removed. The dielectric fluid also flushes the particles from the gap, andkeeps the tool and work cool.

The process is used for shaping and sharpening carbide cutting tools,machining the very hard metals used in missile construction ,and other applicationswhere the physical characteristics of the metal or its use makes it impossible, or veryexpensive ,to machine by conventional methods.


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7[A]. DRILLING A HOLE WITH EDMAim: To make a hole in a copper block of dia 10 mm

Tools required: EDM cutter, Fixture, Dielectric fluid.

Procedure : The methodology is as follows.

Description of the equipment:

TYPES;- Sinker EDM Wire EDM

Sinker EDMsometimes is also referred to as cavity type EDM or volume EDM.Sinker EDM consists of an electrode and work piece that is submerged in aninsulating liquid such as oil or dielectric fluid. The electrode and work piece areconnected to a suitable power supplied. The power supply generates an electrical

potential between the two parts. As the electrode approaches the work piece, dielectricbreak down occurs in the fluid forming an ionization channel, and a small spark jumps.The resulting heat and cavitations vaporize the base material, and to some extent, theelectrode. Those sparks strike on a at a time in huge numbers at seemingly randomlocations between the electrode and work piece. As the base metal is eroded, and thespark gap subsequently increased, the electrode is lowered automatically by themachine so that the process can continue uninterrupted. The typical part geometry is tocut small or odd shaped angles. Vertical, orbital, vectorial, directional, helical, conical,rotational, spin and indexing machining cycles are also used.

WIRE EDM, In wire electrical discharge machining (WEDM), or wire-cut EDM, athin single-strand metal wire, usually brass, is fed through the work piece, typically

occurring submerged in a tank of dielectric fluid. This process is used to cut plates asthick as 300mm and to make punches, tools and dies from hard metals that are difficultto machine other methods. The wire, which is constantly fed from a spool, is heldbetween upper and lower diamond guides. Along with tighter tolerances multi-axis EDMwire cutting machining center have many added features such as: Multi-heads forcutting two parts at the same time, controls for preventing wire breakage, automatic self-threading features in case of wire breakage, and programmable machining strategies tooptimize the operation.

Wire cutting EDM is commonly used when low residual stresses are desired.

Applications;

Prototype Production: The EDM process is most widely used by the mould-makingtool and die industries, but is becoming a common method of making prototype andprototype and production parts, especially in the aerospace, automobile and electronicsindustries in which production quantities are relatively low. In Sinker EDM, a graphite,


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copper tungsten or pure copper electrode is machined into the desired (negative) shapeand fed into the work piece on the end of a vertical ram.

Coinage die making.

For the creation of dies for producing jewelry and badges by the coinage (stamping)process, the positive master may be made from sterling silver, since(with appropriatemachine settings) the master is not significantly eroded and is used only once. Theresultant negative die is then hardened and used in a drop hammer to produce stamped

flats from cutout sheet blanks of bronze, silver, or low proof gold alloy. For badges theseflats may be further shaped to a curved surface by another die. This type of EDM isusually performed submerged in an oil-based dielectric. The finished object may befurther refined by hard (glass) or soft (paint) enameling and/or electroplated with puregold or nickel. Softer materials such as silver may be hand engraved as a refinement.

Small Hole drilling

Small hole drilling EDM is used to make a through hole in a work piece in through whichto thread the wire in Wire-cut EDM machining. The small hole drilling head is mountedon wire cut machine and allows large hardened plates to have finished parts erodedfrom them as needed and without pre-drilling. There are also stand-alone small hole

drilling EDM machines with an x-y axis also known as a super-drill or hole popperthatcan machine blind or through holes.EDM Drills bore holes with a long brass or coppertube electrode that rotates in a chuck with a constant flow of distilled or deionizer waterflowing through the electrode as a flushing agent and dielectric. The electrode tubesoperate like the wire in wire-cut EDM machines, having a spark gap and wear rate.Some small hole drilling EDMs are able to drill through 100mm of soft or throughhardened steel in less than 10 seconds, averaging 50% to 80% wear rate. Holes of 0.3mm to 6.1mm can be achieved in this drilling operation. Brass electrodes are easier tomachine but are not recommended for wire- cut operations due to eroded brassparticles causing brass on brass wire breakage, therefore copper is recommended.

Procedure: The given job is fixed in the vice of EDM.1. The machine is switched on for the circulation of dielectric fluid.2. Then the top of the tool is brought near to the job so that the feed can be

completed in a short time.

3. Then the required level of fluid is to maintained in such a way that the jobshould be completely dripped in the fluid.

4. Select proper range of the tool feeding.

5. Start the machine by generating a spark between the tool and job & therequired hole is generated by erosion of the particles.

Safety Precautions:

1. Do not touch the tool or job or liquid during machining to avoid shocks.

2. Do not mix the water or splash the water during machining to avoidcontamination of cutting fluid.

3. Do not start the machine without the cutting fluid.

4. Be aware the smoke that is generated during machining and wear propermasks.

Result: The given work piece is drilled a hole of diameter 10mm is successfullycompleted in EDM machine.


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8. SHEET METAL JOINING BY RIVETS, SOLDERING ANDBRAZING.

Riveting:-Rivets are used to fasten two or more sheets of metal together. Tin mensrivets with flat heads are used on sheet metal work. Light sheet metal is usuallypunched for riveting, while the heavier sheets are drilled. A solid punch, rivet- set, snap

and a hammers are the tools required for the job. The shapes of rivets used in sheetmetal work.

The following rules must be observed while riveting sheet metal work;

1) Diameter of rivet = 1.2 x thickness of one plate.

2) Distance from the edge of the hole to the edge of the plate = 1.5 x diameter of

rivet.3) Length of the projecting shank = diameter of rivet.

Shapes of rivets:

FlatHead or Tin Mans Rivet. --- For thin metal.

Bifurcated Rivet. --- For soft materials.

SnapHead Rivet. --- Used for general engineering works.

CountersunkHead rivets. --- 900for general work.

1200for thin sheet metal.

For better results, it is advisable to drill all the holes in one plate and only one in the

other. Secure the plates with one rivet and then complete the drilling of the remainingholes.


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8[A].SHEET METAL JOINING BY RIVETSAIM:- To make semi permanent joint by riveting. 1) Solid riveting. 2) Blind riveting

Material required:- Aluminum sheets2 (5mm) , Rivets (solid& blind).

Machine required:- Sheet metal cutter, hand drill, rivet gun.

Measuring instruments:- Steel rule, vernier calipers.Tools:- Drill, Hand vice, Bench vice, Smooth file, Snap, Spacer& Dolly.

Sequence of operations:-

1) Aluminum sheet is cut into required dimensions.2) Using a smooth file, the corners are filed.3) The plate is hammered using a mallet in order to minimize universes in

them.4) Marking is done according to standard.5) The holes are drilled, using drilling machine & the extra mat near the

holes is filed using a smooth file.

6) Riveting is done.Procedure:-

- Aluminum sheet is taken & cut into required dimensions & cleaned.

- Using a smooth file the corners are filled reliving the sharp unwanted even roughsurface.

- The plates are hammered by using a mallet to straight then up.

- Markings are made for holes using the scriber & steel rule.

- Using a drilling m/c ,holes are drilled of required dimensions.

- Using a file the unwanted, upward projection which occurring during hole drilling arefiled.

- Hole drilling in plates is done by fixing the plates in hard vice.

- Fix the dolly firmly in bench vice & given rivets on it followed by plate via the drill hole& hammer it using ball point hammer.

- Using spacer finish the rounded head of rivet.

Precautions:-

1) Snaps& dolly should be closer properly.

2) Gaps bet plate or plates or rivets should be hammered well.

3) Holes should be drilled of correct size of rivet shank.

4) Rivets dist from the plates edge should be properly maintained as per I Sstd

Result:- Solid riveting& blind riveting is completed for a given sample


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9. COMPUTER NUMERICAL CONTROL (CNC)

XL Turn: - A2 axes CNC slant bed lathe with Fanuc emulated control programmingsoftware. The software ware incorporates major functions and facilities used onindustrial controls with further option of linking the machine to CAD/ CAM and FMS(Flexible manufacturing System. XL Turn that performs drilling, boring, reaming,

grooving, threading, parting, roughing, chamfering, tapping of circular work pieces, usingCNC programming .

Introduction: - CNC program is define as a program which contains various codes whichhave to be followed according to the given dimensioning methodology operatingsoftware.

There are two types of diminishing systems.

1) Absolute Dimension system

2) Incremental Dimension system.

Example:- Absolute Dimension system Incremental Dimension system

------------------------- -----------------------------------------

X Y X Y------------------------ -----------------------------------------

P1 0 0 P1 0 0

P2 20 0 P2 20 0

P3 20 20 P3 0 20

P4 70 20 P4 50 0

P5 70 0 P5 0 -20

P6 100 0 P6 30 0

P7 100 40 P7 0 40

P8 70 70 P8 -30 30P9 0 70 P9 -70 0

-------------------------- ------------------------------------


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A standard billet (raw material) can be represented for a diameter of 20mm and lengthof 70mm in CNC program methodology is given by various types of codes.

Various types of codes:-

G- codes:- They are instructions described in the machine tool movement in a program.

a) G00 -- Rapid travel.

b) G01 -- Linear interpolation (cutting feed)

c) G02 -- Circular interpolation (clock wise)

d) G03 -- Circular interpolation (anti- clock wise)

e) D well 04 -- Idle period to the cutter.

f) G20 -- Input data in inches.

g) G21 -- Input data in metric units.

h) G28 -- Go to reference point. (home portion to the tool)

i) G70 --- Finishing of the cycle.j) G71 -- stock removal is turning. (Multiple turning cycle)

k) G72 -- multiple facing cycles.

l) G73 -- Pattern repeating cycle.

m) G74 -- drilling cycle (peck drilling cycle)

n) G75 -- grooving cycle.

o) G76 -- Multiple threads cutting cycle.

p) G90 -- Box turning cycle.

q) G92 -- Thread cutting

r) G94 -- Box facing.s) G98 -- Feed/ min.

t) G99 -- Feed / revolution.

M. Codes:- These are also called miscellaneous codes.

1) M00 -- Program stop.

2) M03 -- Spindle forward.

3) M05 -- Spindle stop.

4) M06 -- Automatic tool charge.

5) M30 -- Program stop & rewind.


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9[A]. GENERATION OF COMPUTER NUMERICALCONTROL (CNC) PROGRAM

Aim: To generate a plain & step turning program using CNC software


tolerances0.05mm

Software required : CNC train

Tools required: Single point cutting tool, Align key and spanner

Program:-

0 0005

G21 G28

G28 U0 WO

M06 T0202

M03 S1200

G00 X26 Z2

G71 U0.5 W0.5 R1

G71 P10 Q20 U0.1 W0.1 F60

N10 G01 X0

G01 Z0

G01 X10 Z0

G03 X15 Z-5 R3

G01 X15 Z-15

G03 X20 Z-20 R3

G01 X20 Z-30N20 G03 X25 Z-35 R3

G70 P10 Q20 S2000 F40

G28 U0 W0

M05

M30

Result: The required program is executed and the given shape on the work piece issuccessfully completed.


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10. WELDING

Introduction : - Welding is a process of joining metals by heating them to a suitabletemperature at which they melt and fuse together.

1.Arc Welding:- In arc welding the heat required for joining the metals is obtained froman electric. Transformers or motor generator sets are used as arc weldingmachines. These machines supply high electric currents at low voltage and an electrodeis used to produce the necessary arc. The electrode serves as the filler rod and arcmelts the surfaces so that the metals to be joined.

Requirements of Arc welding:-

1. Welding machine.2. Cables or leads.3. Electrode holders.4. Cable connectors or lugs.5. Ground clamp.6. Chipping hammer.7. Wire brush.8. Face shield.9. Protection clothing.

Fundamental of weld joints:-

2. Butt joint.3. Lap joint.4. Corner joint.5. T- Joint.

6.Edge joint.

Positions:-

1. Flat and down hand positions.


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2. Horizontal positions.

3. Vertical positions.

4. Overhead positions.

2. Gas welding:-Gas welding is a welding in which a combination of gases are used to obtain aconcentrated flame hot enough to melt and fuse the ends of the parts to be joined.

It is the gas welding process where the parts to be joined are heated with a flameproduced by the combination of OXYGEN and ACETYLENE gas.

Note: 1. In oxygen, acetylene welding, the flame must be supplied by acorrect balance of oxygen and acetylene so that it is neither oxidizing nor carburizing,since either of these flames would weaken the weld.

2. Oxygen regulators have Right hand threads with plain nuts andAcetylene regulators have Left hand threads with notched hexagon nuts so that theycan not be confused. The Regulator is closed by unscrewing the regulating screw.

Types of flames: - The correct adjustment of the flame is important for efficient welding.

The neutral flame is widely used for welding steel, stainless steel, cast iron,copper,aluminium, etc. The carburizing produced with an excess of acetylene, is needed for

welding lead.The Oxidizing flame with excess of oxygen is used for welding brass.Technique of welding:-

Select the proper size tip for the job and insert it carefully into thetorch.

Open the acetylene cylinder valve slightly, say to turn.

Open the oxygen cylinder valve slowly, till it is fully open.

Open the acetylene valve on the torch and turn the acetyleneregulator screw clockwise, until the gauge reads 0.5 to 1kg /cm2of pressure. Then closethe valve on the torch.

Open the oxygen valve on the torch to check the flow and close it.

Put-on the welding goggles, gloves and apron.

Welding process:-

- Prepare the work pieces to be welded and place them in properposition on the welding table.


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- Select proper size tip for the job and fix it to the torch.

- Adjust the welding equipment and light the torch.

- Adjust the torch for neutral flame.

General safety:-

- Always welding in a well ventilated place. Fumes given off fromwelding are unpleasant and in some cases may be injurious, particularly from

galvanized or zinc coated parts.- Do not weld around combustible or inflammable materials, wheresparks may cause a fire.

- Never weld containers which have been used for storing gosling, oil orsimilar materials, with out first having them thoroughly cleaned.

10[A]. WELDING OPERATIONS

AIM:- To make simple exercises like butt, lap, corner an TEE joints in Gas welding,

and Arc welding.

Materials : MS flats , welding electrodes/filler rods and welding machine

Procedure:

1. The given work pieces are first cleaned and sized accordingly.

2. Keep the materials in a predefined manner to make various joints like lap, buttand T .

3. By using proper techniques finish the welding as in the procedure.

Result: Thus making of simple joints by using arc welding and gas welding iscompleted.


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11.METAL JOINING PROCESSES -SOLDERING

Soft soldering is the process of joining metals by the use of filler metal oflow melting point (4500c). The filler metal is an alloy of lead and tin is called solder. Themalting point of solder as less then the base metals. Doping up on the proportions ofeach constituent, its melting point varies from 1500c to 3500c. The percentage of lead

increases the malting point of soldering.

1) Soft solder ----- Lead 37% & tin 63%.

2) Medium solder ----- Lead & tin 50% each.3) Electrical solder ---- Lead 58% & Tin 42%.

4) Plumber solder ----- Lead 70% & Tin 30%.

AIM-: To solder the given G. I. using Black smithy & wire. (using electricsoldering)

Material required:- G.I. sheets & electric wire, kerosene, coal ( both wood coal& railway coal), cotton waste, filler material, flux.

Machine required:- Open hearth furnace, hot iron with a wooden handle,electric air blower.

Sequence of operations (Block smithy soldering.1. Fire the open hearth furnace

2. Soldering iron is placed.

3. A few minutes the electric air blower is switched on the coalstarts burning.

4. Clamped firmly the metals to be soldered in a bench viceand apply layer of flow after cleaning.

5. Solder is applied using red hot soldering iron.

6. Remove irregularities with the hot iron.

Electric soldering:- Start the electric solder leave it for heating.

Remove the insulation for the wire to be soldering.

Clean & twist then together apply flux.


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Filler material wire rubbed slowly against the heated soldering iron.

Spread the metal uniformly on wire & make a uniform joint.

Procedure:- 1) Plug in the soldering rod & leave it for the heating.

2) Now, remove the insulation of wires to be soldered.

3) Twist the copper of the wires & then apply flux for copperends.

4) Lead which is used as filler metal is rubbed slowly against theheated soldering iron rod.

5) Spread the metal uniformly on the wires.

6) Plug out the soldering rod & leave it for cooling.

Result:- The wires are joined using electrical soldering successfully.

11[A]. BRAZING

Brazing is similar to silver soldering but it is used when a much stronger jointis needed. The basic principle of brazing is the same whichever method is used. Sodiumfluoride or sodium silicate mixed with water is used as a stopping off compound toprevent the splitter form sticking to areas of to work. The temperature of the work mustbe high enough to melt the smelter. The two surfaces to be joined must be at thesame temperature.The work should cool evenly to prevent distortion and cracking.

Three kinds of oxygen, acetylene flames:-

1. Neutral flame.

2. Carburizing flame

3. Oxidizing flame

AIM:- To join two sheets by brazing process.

Equipment & material required:- Filler rod , flux, Oxyacetylene torch & two mild steelspecimen.

Tools required:- Wire brush, hand gloves, chipping hammer, spark lighter.

Sequence of operations:-

a) Cleaning and preparing the surface .

b) Fluxing both the base metal and filler metal.


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c) Aligning the base metal parts to joined.

d) Fleeting the joint which is used for brazing.

e) Remove flux reside from joint

Theory:-It is the process of joining 2 pieces of metals in which a nonferrous isintroduced in a liquid state between the pieces of metal to be joined & allow it solidly.The filler metal is distributed between the closely filled surfaces of the joint by caliperaction. The melting point of filler metal is above 42000c, but lower than melting pointtemp. of parent metal . During the process no forging action is present & also theparts dont melt. The bond is produced either by formation of solid solution orintermetallic compound of parent metal. The strength of the joint is provided bymetallic bonding. Good brazing process involves preloading, fluxing, properalignment, heating &post clearing. The following are the metals & alloys used for thebrazing process.

1. Cu having melting point of 10800c.Joint clearance is of order 00.05mm & shearstrength of material is 34003800 kg / cm2.

2. Cu alloys, brass, bronze having melting point varying from 850 to 9500c. They aremostly used for joining ferrous metals. Joint clearance is 0.08 to 0.25mm & shear

strength is 25003100 kg /cm2.3. Sliver alloy, sliver & Cu or silver, Cu, Zn, having melting point of 6008500c.The

joint clearance is 0.05 to 0,13mm & strength of joint material is 1500 to 1850 kg /cm2.

4. Al alloys having melting point 5500c to 7800c.

5. Soft solders :- These having melting point of 70-300oC & the joint clearance is0.075 to 0.2mm and strength of joint material 350-450 kg/cm2. Depending onsource of heating the brazing process may be classified as touch brazing,furnace brazing, inductive brazing, resistance brazing, and dip brazing andinfrared brazing.

Description: Oxy-acetylene torch is produced by mixing of oxygen & acetylene inproper ratios. The oxygen and acetylene are stored in the red and yellow coloredtanks respectively for easy identification. The tanks contain gases subjected topressure. They have valves which indicate the outlet pressure as well as inletpressure. The rubber tubes from two tanks are connected to hand held device withnozzle. It consists of valve for regulating gases flow and a mixing chamber the gasesflow rate can be regulated using this value which there by helps in obtaining reducingflame, natural flame and oxygen flame. The nozzle is made of a high temperatureresistant material.

Procedure:- Cleaning & preparing the surface to brazed ,cleaning is done by solvent

acid, pickling and by mechanical mean. It is also essential that joint is joined properlyand clearance between the work parts should be controlled. Fluxing both the base metal& filler metal surface by spraying, brushing or by mechanical means. Aligning the basemetal parts to be joined. Heating the joint. Heat sources that are used for brazing are amolten bath of brazing filler metal. Oxy- acetylene touch, electrical resistance heating orinduction heating. Applying filler metal to the joint. Allow cooling of the brazed joint.Remove flux residue from the completed joint. The given specimen is brazed that isattached or joined.

Precautions:- 1 The surfaces to be brazed thoroughly cleaned.

2 Align the base metal parts to be joined carefully.

3. Regulators must be operated carefully.

Result:- The given specimen is said to be attached or brazed.


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MATERIALS LAB.

12. WOOD GLOOVING PRACTICE

Air craft wood gloving practice (Bonding):-

Aim:- To prepare a banded structure made up of wood and aluminum with the aid ofglue

Work Material:- Wood 75x75x 30mm. and 2 aluminum sheets 75x 75x 6mm.

Theory:- Bonding is a method of joining bounding material called glue which is to beplaced b/m the member to be joined, generally bonding is done b/m the member so thatthe resultant bonded structure will have hybrid properties ie. the combination ofproperties of both the materials.

Bonded structures are widely used in structures of various a/c components like wing, offuselage etc as a bonded joint b/m aluminum & wood has a strength that to weight ratiocompared with the individual materials which is the primary requirement for an a/c.

Procedure:- 1) Take a given wooden piece and san it to the given dimensions.

2) With the help of filing, give the surface finish.

3) Mark the aluminum sheet to 75x75x6mm with the help of scale and

scriber, cut it from the main sheet by using cutter4) With the aid of metal file, give the metals a good edge finish.

5) Finally bond the aluminum sheet & wooden piece with glue.

6) Change it in order to make the bond dry and strong.

Precautions:- - Mark the dimensions without any parallel errors.

- Paper case is to be taken while sawing the wooden piece & filing ofaluminum sheet.

-Bonded structure is properly clamped & allowed to dry.

Result:- The respective bonded structure is (bond) obtained.


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13. STUDY OF PROPERTIES OF SANDWICHSTRUCTURES

Aim: Study of the properties of a sandwich structure

Materials required: Wood 100mm x 10mm x 3 mm, Aluminium100mm x 10mm x 2 mm

Procedure:

1. The given wooden material is made to the standard dimensions as given

in the requirement.2. Then the given aluminum flat are so arranged over the surface of the wood

material.

3. This type of structural component is called fletched beam and can havehigh strength and less weight.

4. These structural members are used in the fabrication of air craft structuralmembers like wings, fuselage etc.

Result: The given materials are fabricated and made as sandwich structuressuccessfully.


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14. STUDY OF MICROSTRUCTURES OF NON FERROUS METALS

Aim:- Study of microstructure for Aluminum alloy and copper alloy material

Aluminum Structure Copper structure

Apparatus:- Microscope, Aluminum alloy, test specimen, copper alloy, alloy testspecimen and magnifying lens.

Procedure:- 1) A specimen surface is grinded in belt type rough surface grinder.

2) The specimen is rinsed in water and same surface is polished usingpolishing, grinding machine

3) Then the solution is applied on the surface of the specimen for clearvision of the Microstructure

A) Aluminum alloy:- The specimen is 3% copper and 6% Si, Al, Alloy. Themicrostructure showsvery fine grids of Al, Si elates in a matrix form of Al, salt solution.The particles longer and sharp. They are more angular. The microstructure of Al alloyunder the acid solution.

b) Copper alloy: - The specimen is wrought commercial bars. The specimen is annelidafter cold working to draw into a wrought. The composition is 60% copper, Al 40%. Theescheat solution for this is Ammonium and H2O2.

Result:- The study of microstructure of Al. alloy and Cu. Alloy was completed.


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15. AUTOCLAVE FOR DIFFERENT GEOMETRICALSTRUCTURES

Aim: Study of Autoclave unit for different geometrical structures.

Apparatus required: Autoclave

Description:


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AUTOMATIC AUTO CLAVE

Bag moldingis one of the oldest and most versatile of the process use inthe manufacturing composite parts. The laminae( freshly impregnated with wet resins )are laid up in a mold, covered with a flexible diaphragm or bag and cured with heat andpressure. After the required cured cycle, the materials become an integrated moldedpart shaped to the desired configuration. The general process of bag modeling can bedivided on the basis of the pressure and heat applied to the laminate during curing into

(1) Pressure bag(2) Vacuum bag (3) Autoclave.

Inside chamber of an Autoclave

In the Pressure bag molding, pressure above atmosphere are applied on thelaminate inside the closed mold. The curing is accomplished by heating the mold in anoven.

In Vacuum bag molding, air and other volatiles between the bag and laminateare removed by a vacuum pump. Thus the laminates subjected to atmosphericpressure when it is being cured in an oven.

Autoclave processingof composites is an extension of the vacuum bagtechnique. Autoclave can be pressurized during processing of the composites. In thismethod the composite part is laid up and enclosed in a vacuum bag. Full or partialvacuum is drawn under the bag and gas pressure greater than the atmosphericpressure is applied on the exterior of the bag. Curing of the polymer is initiated byraising the part temperature int eh autoclave chamber. Augmented pressure exertshigher mechanical forces on the layup, increases the efficiency of the transport of thevolatiles to the vacuum ports and results in increased wetting and flow of the resin.

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Aircraft Material & Production -MANUAL