ME 2207 - Manufacturing Technology 1 - Lab Manual

P.A COLLEGE OF ENGINEERING AND TECHNOLOGY POLLACHI – 641 002.

DEPARTMENT OF MECHANICAL ENGINEERING SEMESTER – III

MANUFACTURING TECHNOLOGY LAB - I (STUDENTS LAB MANUAL)

Name: Reg No: INDEX S.No

Date

Name of the Experiment

Mark

1

STUDY OF LATHE

2

MACHINING A WORK PIECE BY FACING, PLAIN TURNING AND STEP TURNING OPERATIONS USING A LATHE

3

MACHINING A WORK PIECE BY TAPER TURNING OPERATION (COMPOUND REST METHOD) USING A LATHE

4

MACHINING A WORK PIECE BY V- THREAD CUTTING AND KNURLING OPERATIONS USING A LATHE

Signature

MACHINING A WORK PIECE BY BORING AND 5

INTERNAL THREAD CUTTING OPERATIONS USING A LATHE

6

STUDU OF SHEET METAL

7

FRUSTUM OF A CONE

8

TRAY

9

STUDU OF WELDING

10

HORIZONTAL WELDING

11

THE VERTICAL WELDING

12

THEOVERHEAD WELDING

13

SAND MOULDING PROCESS

TOTAL

FACULTY INCHARGE

A STUDY ON BASIC MACHINING

INTRODUCTION Machining is the process of converting the given work piece into the required shape and size with help of a machine tool. The most widely used machine tool is lathe. In simple words machining is the process of removing certain material from the work piece. LATHE Lathe is the machine tool which is used to perform several operations on the work piece. Lathe is useful in making several parts which is further assembled to make new machine. Hence lathe is known as “mother of machines”.

BASIC WORKING PRINCIPLE OF LATHE In lathe, the work piece is held in the chuck, a work holding device. The cutting tool is mounted in the tool post. The chuck is rotated by means of power. When the chuck rotates, the work piece also rotates. The tool is moved against the rotating work piece by giving small amount of depth of cut. The material is removed in the form of chips. Continuous feed and depth of cut is given until the required dimensions are obtained in the work piece.

TYPES OF LATHE MACHINES There are different types of lathe machines, they are 1. Centre lathe 2. Tool room lathe 3. Bench lathe 4. Capstan lathe 5. Turret lathe 6. Automatic lathe DESCRIPTION OF LATHE Lathe is a machine which has several parts in it. They are 1. Bed It is the base of the machine. On its left side, the head stock is mounted and on its right it has movable casting known as tailstock. Its legs have holes to bolt down on the ground. 2. Head stock It consists of spindles, gears and speed changing levers. It is used to transmit the motion to the job. It has two types one is the headstock driven by belt and the other one is the gear driven. 3. Carriage Carriage is used to carry a tool to bring in contact with the rotating work piece or to with draw from such a contact. It operates on bed ways between the headstock and tail stock. 4. Saddle It is a „H‟ shaped part fitted on the lathe bed. There is a hand wheel to move it on the bed way. Cross slide, compound rest, tool post are fitted on this saddle. a) Cross slide It is on the upper slide of saddle in the form of dove tail. A hand wheel is provided to drive the cross slide. It permits the cross wise movement of the tool (i.e.) movement of tool towards or away from the operator

b) Compound rest It is fitted over the cross slide on a turn table. It permits both parallel and angular movements to cutting tool.

c) Tool post It is fitted on the top most part of the compound rest. Tool is mounted on this tool post. Cutting tool is fixed in it with the help of screws.

5. Apron It is the hanging part in front of the carriage. It accommodates the mechanism of hand and power feed to the cutting tool for carrying out different operations.

6. Lead screw It is a long screw with ACME threads. It is used for transmitting power for automatic feed or feed for thread cutting operation.

7. Tail stock It is located at the right end of the lathe bed and it cn be positioned anywhere in the bed. It is used for supporting lengthy jobs and also carries tool to carry out operations such as tapping, drilling, reaming.

WORK HOLDING DEVICES 1. Lathe centers They are used to support work. It has two categories of centers. Live center is one which is fitted in the headstock spindle. Dead is another one which is fitted in the tail stock. 2. Chuck It is a device used to hold a job. It is easily fitted on the thread cut on the end of head stock spindle. Various types of chuck are a) Two jaw chuck

b) three jaw chuck

c) four jaw chuck

d) collet chuck

e) Magnetic chuck

Three Jaw Universal selfcentering chuck

Four Jaw Independent chuck

3. Face plate

4. Catch plate 5. Lathe carriers or dog‟s 6. Steady rest 7. Mandrel 8. Follower rest CUTTING TOOLS USED For making a finished job on lathe machine, various types of cutting tools are used. One of them is single point cutting tool which is used to perform several operations on the work piece. Various types of cutting tools are 1. FACING TOOL It is used for facing the longitudinal ends of the job. Its shape is like a knife. 2. ROUGH TURNING TOOL It is used to remove excess material from the work piece in quick time. It can be used to give large depth of cut and work at coarse feed. 3. FINISHING TOOL It is used for getting smooth finish on the work piece. Its point is a little more round. 4. RADIUS TOOL Jobs which need round cutting are done with this tool. Its type is a) Convex radius tool

b) concave radius tool

5. PARTING TOOLS It is used to cut the jobs into two parts. It is also used for grooving. 6. FORM TURNING TOOL It is used for jobs which require both convex and concave turning. 7. THREAD CUTTING TOOL

It is used for making internal or external threads on the work piece. The tool nose is designed with a definite profile for taking threads. 8. DRILL TOOL It is used for making holes of various diameters on the job. Drill bit of various sizes of diameter are available.

9. BORING TOOL It used for enlarging the drill hole. 10. KNURLING TOOL Drawing slanting or square projecting lines on the surface of a job is known as knurling. It is used for making better grip on the surface of a job.

TOOL MATERIALS  The single point cutting tools are made of high speed steel. (H. S. S)  The main alloying elements in 18 – 4 – 1 HSS tools are 18 % tungsten, 4% chromium and 1 % Vanadium. 5 to 10 % cobalt is also added to improve the heat resisting properties of the tool.  General purpose hand cutting tools are usually made from carbon steel or tool steel.  Carbide tipped tools fixed in tool holders, are mostly used in production shops.

NOMENCLATURE OF SINGLE POINT CUTTING TOOL

CUTTING TOOL ANGLES  Top rake angle (back rake angle) If the slope is given to the face or surface of the tool and if this slope is along the tools length then it is called top rake angle. It is usually 15 to 20.  Side rake angle If the slope is given to the face or top of the tool along the tools width then it is called side rake angle. It lies between 6 and 15.  Clearance angle (relief angle) Types: 1. Side clearance angle

2. End clearance angle.

They are provided to keep surface of the tool clear of the work piece.  Cutting edge angle Types: 1. Side cutting edge angle – (generally 15) it is an angle, the side cutting edge makes with the axis of the tool 2. End cutting edge angle – (from 7 to 15) it is an angle, the end cutting edge makes with the width of the tool.  Lip angle (cutting angle) It is the angle between the face and the end surface of the tool.  Nose angle It is the angle between the side cutting edge and end cutting edge. LATHE OPERATIONS 1. FACING  It is done for getting fine finish (good surface finish) on the face of the job.  Facing tool is set at an angle to the work piece.  The tool is fed from the centre of work piece towards the outer surface against the rotating work piece.  Depth of cut is low for the facing operation.

2. PLAIN TURNING  It is done for reducing the diameter of the work piece.  A cutting tool with 70 setting angle is used for roughing operation.  More feed is given for rough turning while less feed is given for finishing.  Work piece is held in chuck and tool is set to center height of the work piece.

3. STEP TURNING  It is similar to the process of turning but in this case different diameter in step of various sizes is taken on the work piece. 4. TAPER TURNING  It is different from the turning operation.  Taper is defined as uniform change in the diameter of a work piece measured along its length.

Where

D

–

large Diameter

d

–

Small diameter

l

–

Length of taper

5. KNURLING  It is process of making serrations on the work piece.  Knurling tools of different shape and size are used to make grip on the work piece. It has two hardened steel rollers.  The tool is held in tool post and pressed against the rotating work piece.  Work piece is rotated at lower speed and small amount of feed is given.

6. DRILLING  It is a process of making a hole on the work piece  Job is held in chuck while the drill is held in the tail stock sleeve.  Feed is given by rotating the hand wheel in the tail stock which pushes the tailstock sleeve. CUTTING SPEED  It is the peripheral speed of the work past the cutting tool.  It is the speed at which metal is removed by the tool from the work piece.  It is expressed in meter / minute.

D – Diameter in mm N – Spindle speed in rpm FEED  It is defined as the rate of tool travel across a surface cutting it.  It is the distance of the tool advances for each revolution of the work piece.  It is expressed in mm/revolution.

DEPTH OF CUT  It is the perpendicular distance measured from the machined surface to the uncut surface of work. It is expressed in mm.

d1 = diameter of work before machining d2 = diameter of work after machining

SAFETY PRECAUTIONS

1) Job should be tightly held in the chuck. 2) If the job is held in between the centers, then apply grease on the nose of dead center, otherwise it will burnt out due to excess heat. 3) Do not measure the job while it is rotating. 4) Do not leave the chuck key in the chuck. 5) Do not try to stop the lathe chuck or job with hands 6) Do not handle metal chips by hand. 7) Do not give more depth of cut while the job is rotating at high speed. 8) Tighten the tool I n the tool post. 9) Do not stand close to the rotating job or bring your face to it. 10) Do not reduce or increase the speed during the lathe operations.

Result :

EX.NO: MACHINING A WORK PIECE BY FACING, PLAIN TURNING AND STEP TURNING OPERATIONS USING A LATHE AIM: To machine a work piece by facing, plain turning and step turning operations using a lathe. MATERIALS REQUIRED: Mild steel polished round rod -  32 X 100 mm TOOLS REQUIRED: 1. Lathe machine 2. Cutting tool 3. outside Caliper 4. Steel Rule 5. Vernier Caliper PROCEDURE: 1. The given work piece is held firmly in a lathe chuck. 2. The cutting tool is set in a tool post such that the point of the cutting tool coincides with the lathe axis. 3. The machine is switched on to revolve the work piece at the selected speed. 4. By giving Cross feed and longitudinal feed to the cutting tool, the facing and turning operations are done respectively. 5. The machine is switched off. 6. The work piece is removed from the chuck and all the dimensions are measured and checked.

GIVEN WORK PIECE (FIG: 1)

FINISHED WORK PIECE (FIG: 2)

RESULT: The given work piece as shown in fig (1) is subjected to facing, plain turning and step turning operations to become a finished work piece as shown in fig (2).

EX.NO: MACHINING A WORK PIECE BY TAPER TURNING OPERATION (COMPOUND REST METHOD) USING A LATHE AIM: To machine a work piece by facing, plain turning and taper turning operation (compound rest method) using a lathe. MATERIALS REQUIRED: Mild steel polished round rod -  32 X 83 mm TOOLS REQUIRED: 1. Lathe machine

4.Steel Rule

2. Cutting tool

5.Vernier Caliper

3. Outside Caliper

6.Spanner

CALCULATION: The taper angle is calculated using the following formula: 1  D  d   Taper angle () = tan   2l 

Where D = large diameter of taper in mm d = small diameter of taper in mm l = length of tapered part in mm  = angle of taper PROCEDURE: 1. The given work piece is held firmly in a lathe chuck. 2. The cutting tool is set in a tool post such that the point of the Cutting tool coincides with the lathe axis. 3. The machine is switched on to revolve the work piece at the selected speed. 4. By giving Cross feed and longitudinal feed to the cutting tool, the facing and turning operations are done respectively. 5. The compound rest is swiveled for the calculated taper angle. 6. By giving angular feed to the cutting tool through the compound slide the taper turning operation is done. 7. The machine is switched off. 8. The work piece is removed from the chuck and all the dimensions are measured and checked.

GIVEN WORK PIECE (FIG: 1)

FINISHED WORK PIECE (FIG: 2)

RESULT: The given work piece as shown in fig (1) is subjected to facing, plain turning and taper turning operation (compound rest method) to become a finished work piece as shown in fig (2).

EX.NO: MACHINING A WORK PIECE BY TAPER TURNING OPERATION (TAPER TURNING ATTACHMENT METHOD) USING A LATHE AIM: To machine a work piece by facing, plain turning and taper turning operation (Taper turning attachment method) using a lathe. MATERIALS REQUIRED: Mild steel polished round rod -  32 X 83 mm TOOLS REQUIRED: 1. Lathe machine with taper turning attachment 2. Cutting tool

5.Vernier Caliper

3. Outside Caliper

6.Spanner

4. Steel Rule CALCULATION: The taper angle is calculated using the following formula: 1  D  d   Taper angle () = tan   2l 

Where D = large diameter of taper in mm d = small diameter of taper in mm l = length of tapered part in mm  = angle of taper

PROCEDURE: 1. The given work piece is held firmly in a lathe chuck. 2. The cutting tool is set in a tool post such that the point of the Cutting tool coincides with the lathe axis. 3. The machine is switched on to revolve the work piece at the selected speed. 4. By giving Cross feed and longitudinal feed to the cutting tool, the facing and turning operations are done respectively. 5. The taper turning attachment is attached and set for the calculated taper angle. 6. By giving angular feed to the cutting tool the taper turning operation is done.

7. The machine is switched off. 8. The work piece is removed from the chuck and all the dimensions are measured and checked.

GIVEN WORK PIECE (FIG: 1)

FINISHED WORK PIECE (FIG: 2)

RESULT: The given work piece as shown in fig (1) is subjected to facing, plain turning and taper turning operation (Taper turning attachment method) to become a finished work piece as shown in fig (2).

EX.NO: MACHINING A WORK PIECE BY V- THREAD CUTTING AND KNURLING OPERATIONS USING A LATHE AIM: To machine a work piece by facing, plain turning, knurling and external thread cutting operations using a lathe. MATERIALS REQUIRED: Mild steel polished round rod -  32 X 100 mm TOOLS REQUIRED: 1. Lathe machine

5.Outside Caliper

2. Turning tool

6.Steel Rule

3. Knurling tool

7.Vernier Caliper

4. External V – thread cutting tool CALCULATION: The number of teeth on change gears is calculated using the following formula: Driver teeth/ Driven teeth = Pitch of the work / pitch of the lead screw PROCEDURE: 1. The given work piece is held firmly in a lathe chuck. 2. The cutting tool is set in a tool post such that the point of the Cutting tool coincides with the lathe axis. 3. The machine is switched on to revolve the work piece at the selected speed. 4. By giving Cross feed and longitudinal feed to the cutting tool, the facing and turning operations are done respectively. 5. The speed of the work piece is reduced. 6. The knurling operation is done using knurling tool. 7. The machine is switched off and the change gears of calculated teeth(as per calculation) are connected. 8. Again the machine is switched on. 9. The external thread cutting operation is done using external V–thread cutting tool by engaging thread cutting mechanism. 10. The machine is switched off. 11. The work piece is removed from the chuck and all the dimensions are measured and checked.

GIVEN WORK PIECE (FIG: 1)

FINISHED WORK PIECE (FIG: 2)

RESULT: The given work piece as shown in fig (1) is subjected to facing, plain turning, knurling and external thread cutting operations to become a finished work piece as shown in fig (2).

EX.NO: MACHINING A WORK PIECE BY BORING AND INTERNAL THREAD CUTTING OPERATIONS USING A LATHE AIM: To machine a work piece by facing, plain turning, boring and internal thread cutting operations using a lathe. MATERIALS REQUIRED: Mild steel polished round rod -  32 X 100 mm TOOLS REQUIRED: 1. Lathe machine 2. Turning tool 3. Boring tool 4. Internal V – thread cutting tool

5.Outside Caliper 6.Steel Rule 7.Vernier Caliper

CALCULATION: The number of teeth on change gears is calculated using the following formula:

Driver teeth/ Driven teeth = Pitch of the work / pitch of the lead screw. PROCEDURE: 1. The given work piece is held firmly in a lathe chuck. 2. The cutting tool is set in a tool post such that the point of the Cutting tool coincides with the lathe axis. 3. The machine is switched on to revolve the work piece at the selected speed. 4. By giving Cross feed and longitudinal feed to the cutting tool, the facing and turning operations are done respectively. 5. The speed of the work piece is reduced. 6. The boring operation is done using boring tool. 7. The machine is switched off and the change gears of calculated teeth(as per calculation) are connected. 8. Again the machine is switched on. 9. The internal thread cutting operation is done using internal V–thread cutting tool by engaging thread cutting mechanism. 10. The machine is switched off. 11. The work piece is removed from the chuck and all the Dimensions are measured and checked.

GIVEN WORK PIECE (FIG: 1)

FINISHED WORK PIECE (FIG: 2)

RESULT: The given work piece as shown in fig (1) is subjected to facing, plain turning, boring and internal thread cutting operations to become a finished work piece as shown in fig (2).

STUDY ON SHEET METAL

INTRODUCTION Sheet metal work is the working on the metal of 16 gauge to 30 gauge with hand tools and simple machines into different forms by cutting, forming into shapes and joining. APPLICATION OF SHEET METAL It is used for making hoppers, funnels, various ducts chimneys, ventilating pipes, machine tool guards, boilers etc. It is extensively used in major industries like air craft manufacturing, ship building, automobile body building and fabrication of ducts in air conditioning equipments. PRINCIPLE INVOLVED Generally all sheet metal work patterns are based on the development of the surfaces of a number of geometrical models like prism, cylinder, pyramid and cone. Besides development of surfaces, geometrical projections are also used for sheet metal work. GENERAL PROCEDURE FOR SHEET METAL WORK The exact size and shape of the sheet to be cut is given by the development of the concerned object. The development is drawn on a flat sheet metal and then the sheet is cut. Then it is folded or rolled to the required shape before the joints are made by welding or any other form of fastening. SPECIFICATION OF SHEET METAL The sheets are specified by standard gauge numbers. Each gauge designates a definite thickness. The gauge number can be identified by standard wire gauge or SWG. SWG

10

12

14

16

18

20

22

24

26

30

Thickness (mm)

3.2

2.6

2.0

1.6

1.2

0.9

0.7

0.6

0.4

0.3

METALS USED IN SHEET METAL WORK The most commonly used sheet metals are a. Black iron – used for making tanks, pans and stove pipes etc. b. Galvanized iron – used for making pans, buckets, furnaces, heating ducts, cabinets etc. c. Stainless steel – domestic appliances such as vessels since it is anticorrosive, it is well suited for handling of liquid helium, hydrogen, nitrogen and oxygen that exists at cryogenic state. d. Copper – used for making cutters, expansion joints, roof flashing and hoods. e. Aluminium – used for making house hold appliances, refrigerator trays, vessels used in chemical and food industries, electrical industries, structural applications etc. f. Tin plate – used for making roofs, food containers, dairy equipments, furnace fittings, cans and pans etc. g. Lead – used for lining in tank, flooring in chemical plants. And also in battery paltes. TOOLS USED IN SHEET METAL WORK I.

Cutting tools a. Chisels They are used for cutting sheets, rivets, bolts and chipping operations. Though there are many types of chisels available, round nose chisel and flat nose chisel are used for sheet metal work.

b. Snips or Shears Snips are hand shears; varying in length from 200mm to 600mm. 200mm to 250 mm length is most commonly used. Straight end and curved snips are mostly used for cutting along outside curves and straight lines, trimming along inside curves respectively.

II.

Striking tools a. Hammers They are used for hollowing, stretching, leveling, riveting, strengthening of sheet metal joints etc. the mostly used hammers are ball peen hammer, straight peen hammer, riveting hammer, mallet etc.

b. Punches It is used for marking out work locating centers etc. the widely used punches are dot punch, hollow punch and center punch.

III.

Supporting tools Stakes They are the sheet metal worker‟s anvil used for bending, hemming, seaming, forming etc, using hammers or mallet.

IV.

Bending tools Pliers: They are used for bending the sheet metal to the required shape. It also used for holding and cutting the sheet metal. Flat nose pliers and round nose pliers are used in the sheet metal work for forming and holding.

V.

Layout tools Steel rules: It is used for measuring and laying out small work. It can measure with an accuracy of upto 0.5mm. Scriber: It is long wire steel with its one end sharply pointed and hardened to scratch line sheet metal for laying out patterns.

Dividers: It is used for drawing circles or arcs on sheet metal. They are used to mark a desired distance between two points and to divide lines into equal parts.

Sheet Metal gauge: It is used to find the thickness of the sheet metal. The various gauges are standard wire gauge, Birham wire gauge and American wire gauge.

VI.

Other Tools a. Groover: The process of joining two sheet metal jobs, their ends are grooved with the help of grooving tools and this is known as grooving. b. Hand dolly: It is a steel bock rectangular in shape and fitted with a handle in the bottom of the block.

SHEET METAL OPERATIONS The major types are Shearing, Bending, Drawing, Squeezing. Shearing:

Bending: It means that the metal is stressed beyond the elastic limit. So that the metal is bent into right angle and forming occurs when complete items or parts are shaped. It incorporates angle bending, roll bending, and roll forming and seaming.

Drawing: It is the operation of producing cup shaped components from the sheet metal by many number of punching strokes. It is performed by placing a metal blank over a stationary die and exerting a calculated pressure from a punch against the blank.

Squeezing: It is the one of the methods of forming ductile material. Riveting, cold heading and rotary swaging are very common process of squeezing. Rivets are used to join two or more sheets of metal together.

SHEET METAL JOINTS Sheet metal working incorporates a wide variety of hems and seams. HEM: a hem is an edge or border made by folding. Types of Hem: single hem, double hem, wired edge.

Double Hem SEAM: A seam is a joining made by fastening two edges together. Types of seam: Single Seam, Double Seam, Grooved Seam.

SHEET METAL PATTERN DEVELOPMENT METHODS In order to fabricate an object out of sheet metal it is necessary to know the exact shape and size of the sheet metal required. For that a pattern which is the flat outline of the object should be prepared. The objects like cylinder, cone, prism, pyramids etc. are developed from the development of surfaces.

The following are methods used to make patterns in the sheet metal 1. Parallel line method 2. Radial line method 3. Triangulation method Development of cylinder using parallel line method Cylinder is wrapped around the paper. When the paper is opened, it is rectangular of size. Radial line method It is used for the development of cones and pyramids in which the apex is taken as center and its slant edge or generator as the radius for its development.

SAFETY PRECAUTIONS 1. Heavy sheets must be handled by using gloves. 2. Check whether head portion of the mallet and hammer should be tightly fixed to the handle. 3. Respective snips should be used according to the sheet thickness. 4. Burrs should be removed in the edges of the sheet metal after the cutting process. 5. Do not let sheet metal slip through your hands. 6. While cutting operation, blade should be perpendicular to the job and along the marking line. 7. Adequate care should be taken while folding, hemming, seaming operations. 8. Waste materials should be cleaned by using wire brush. 9. Necessary sheet metal working tools should be collectively selected and handled because that avoids confusion. 10.High force should not be applied while leveling the plate because that leads to malleability state of sheet metal.

EX. NO:

RECTANGULAR TRAY

DATE: AIM To make a Rectangular Tray from the given sheet metal. MATERIAL SUPPLIED 26 gauge Galvanized Iron (G.I) sheet. TOOLS REQUIRED 1. Steel Rule 2. Mallet 3. Scriber 4. Divider 5. Snips 6. Ball Peen Hammer 7. Stakes WORKING PROCEDURE 1. First the work pieces must be thoroughly cleaned to remove rust, scale and other foreign material. 2. The size of the given sheet is checked for its dimensions using a steel rule. 3. Then the sheet is leveled on the leveling plate using a mallet. 4. The dimensions are marked as shown in figure. 5. The sheet is cut as per the marked dimensions by straight snips. 6. A single hemming is made on the four sides of the tray as shown in fig. 7. These four sides of the tray are bent to 90 degrees using stakes anvil. 8. Finally all the corners of the tray are joined.

RESULT Thus the rectangular Tray is made from the given sheet metal.

EX. NO:

FRUSTUM OF A CONE

DATE: AIM To make a Cone Frustum from the given sheet metal. MATERIAL SUPPLIED 26 gauge Galvanized Iron (G.I) sheet. TOOLS REQUIRED 1. Steel Rule 2. Mallet 3. Scriber 4. Divider 5. Snips 6. Ball Peen Hammer 7. Stakes 8. Protractor WORKING PROCEDURE First the work pieces must be thoroughly cleaned to remove rust, scale and other foreign material. 1. The size of the given sheet is checked for its dimensions using a steel rule. 2. The required shape is first produced in a paper which is used for reproducing the exact size on the sheet metal. 3. The slanting angle of the sector is calculated by using the formula 360X(R/L).Where, R is a base circle radius and L is a slant height. 4. The required shape is cut from the paper. 5. Then the exact shape of the paper cut is placed on the G.I sheet, so that the same size can be reproduced on the sheet metal using scriber. 6. Then the sheet is folded using funnel stake to make cone shape. 7. Then edges of the folded portion are joined together by seaming process using groover. RESULT Thus the cone frustum is made from the given sheet metal.

WELDING EXCERCISES INTRODUCTION  Welding is one of the metal joining processes.  In welding, metals are used by the application of heat with or without the application of pressure.  During welding the edges of the metal pieces are heated to a high temperature so that they either melt or brought to a plastic condition and then allowed to cool.  Type of welding 1. Plastic welding 2. Fusion welding PLASTIC WELDING: The piece of metal to be joined are heated to the plastic state and then forced together by external force without the filler material. Note: Filler material is used to fill the gap between the joint surfaces. Plastic welding further categorized by the following:1.Forge welding 2.Resistance welding 3.Thermit welding FORGE WELDING The work pieces are placed in a forge or other appropriate furnace and heated with in the area to be joined to the plastic condition. Then parts are quickly superimposed and worked into a complete union by hand or power hammering or by pressing together.

Example > lap welding, Butt welding,”V” welding

RESISTANCE WELDING In resistance welding, a heavy electric current is passed through the metals to be joined over limited area causing them to locally heated to plastic state and the welding is completed by the application of pressure for prescribed period time. Example > Spot welding, Projection welding, Seam welding Butt welding. THERMIT WELDING Thermit welding is a fusion process in which weld is effected by pouring super heated liquid thermit steel, around the parts to be united with or without the pressure. FUSION WELDING The fusion welding is categorized as follows 1. Gas welding 2. Electric welding 3. Thermit welding(without pressure) Gas welding  Gas welding is the process in which the required heat to melt the surface is supplied by a high temperature flame obtained by mixture of two gases.  Usually the mixture of oxygen and acetylene is used for welding purpose. Oxy-acetylene Welding In oxy-acetylene gas welding process, a flame is produced by burning mixture of oxygen and acetylene to get a flame temperature up to 3500°C in two stages. Types of flames The ratio of oxygen and acetylene in the mixture leads to any one of the following flames. Neutral flame Oxidizing flame Carburizing flame

Neutral flame:  This flame has equal volumes of oxygen and acetylene.  According to the application this flame is used to weld steel, stainless steel and cast iron. Oxidizing flame  It has more volumes of oxygen than acetylene.  This flame is used to weld copper and copper alloys. Carburizing flame  It has more volumes of acetylene than oxygen.  This flame is used to weld monel metal, low carbon steel and alloy steel. FILLER MATERIAL It is the metal that is added to the metal that is added to the weld pool to assist in filling the gap. Filler material forms an integral part of the weld. The filler metal is usually available in the rod form. ARC WELDING  In arc welding process, the source of heat is electricity  In arc welding process, coalescence is produced by heating the work piece. With an electric arc stick between an electrode and the work piece.  Welding may be carried out in air or in an inert atmosphere. Principle of Arc welding:  The electricity is important thing in arc welding.  The electricity motor generator or transformer sets are used to supply high electric current and the electrodes are used to produce the necessary arc. The electrode serves as the filler rod and the arc melts the metals to be joined are fused together.  The electrodes are used in arc welding as a filler rod.  The electrodes are made of metallic wire called core wire.

 It is coated uniformly with a protective coating called flux while fluxing an electrode about 20 mm of length is left bare at one end for holding it using electric holder.  It is used to transmit full current from electrode holder to the front end of the electrode coating.  The size or diameter of the core wire will depend upon the amount of weld metal to be deposited and on the type of joint. TOOLS USED IN ARC WELDING: 1. Electric holder 2. Chipping hammer 3. Wire brush 4. Hand screen 5. Helmet 6. Tongs 7. Goggles 8. Hand gloves 1. Electrode holder  It is the device used for mechanical holding the electrode and conducting the current to it.  Electrode holder should be light to minimize fatigue in cured by the welder. Jams are made to hold the bare of the electrode in either a vertical or an angular position. 2. Chipping hammer A chipping hammer is chisel shaped one and it is used to remove slag from the weld bed.

3. Wire brush A wire brush made up of shift steel wire, embedded in wood, removes small particulars of slag from the weld after the chipping hammer has done its job. 4. Hand screen It is protective device used in arc welding, a hand shield is held in the hand of the welder and it is fitted with a suitable fitter lens. 5. Helmet It is used for shielding and protecting the face and neck of the welder and it fitted with fitter lens. 6. Tongs Tongs are used to handle the hot metal – welding job while cleaning, they are also used to hold the metal for hammering. 7. Goggles Chipping goggles are used to protect the eyes while chipping the slag. They are fitted while a plain glass to see the area to be cleaned. 8. Hand gloves Hand gloves are used to protect the hands from the electric shocks, arc radiation and hot spatters.

EX.NO.

THE HORIZONTAL WELDING

Aim: To arc weld two metal piece of mild steel to get the Horizontal Welding.

Tools Required: 1. 2. 3. 4. 5. 6. 7. 8.

Electrode Welding transformer Gloves Tong Chipping hammer Wire brush Welding shield Electrode holder

Procedure:  The mild steel plates to be joined are first cleaned. Using the wire brush to remove dust & rust.  The edges and surface to be welded using the wire brush to remove dust and rust. The edge and surface to be welded are then filled or ground to get the required dimension.  Now the metal plates to be welded are placed in proper position on a cathode plate (that is a metal plate).  The welding electrode is held using an electrode holder and tack welds at two places are made such that the position of the plates do not change while welding (The planes should be at 90° to each other).  Now the electrode is made to touch the metal plates and then electrodes is separated to leave a small gap. (3 to 4 mm) between its tips and the metal plates. This initiates an arc. Once the arc is initiated, the electrode is moved along the length of the metal pieces. For completing the welding process on one side.  Using tongs, the metal plates welded on one side is over turned. Welding is now carried out on this side also in the previously explained manner.  After welding, the plates are allowed to cool for some time. Using a chipping hammer, oxides are removed to complete the exercise.

RESULT: Thus the two mild steel plates are welded to get the Horizontal Welding.

EX.NO

THE VERTICAL WELDING

Aim: To arc weld two metal piece of mild steel to get the Vertical Welding.

Tools Required: 1. 2. 3. 4. 5. 6. 7. 8.

Electrode Welding transformer Gloves Tong Chipping hammer Wire brush Welding shield Electrode holder

Procedure:  The mild steel plates to be welded are first cleaned. Using the wire brush to remove dust & rust. The edges and then filed or ground to get the required dimension.  Now the metal plates to be welded are placed in proper position on a cathode plate (that is a metal plate).  The welding electrode is held using an electrode holder and tack welds at two places are made such that the positions of the plates do not change while welding.  Now the electrode is made to touch the metal plates and then electrodes is separated to leave a small gap. (3 to 4 mm) between its (electrode) tips and the metal plates. This initiates an arc. Once the arc is initiated, the electrode is moved along the length of the metal pieces. For completing the welding process on one side.  Using tongs, the metal plates welded on one side is over turned. Welding is now carried out on this side also in the previously explained manner.  After welding, the plates are allowed to cool for some time. Using a chipping hammer, oxides are removed to complete the exercise.

RESULT: Thus the two mild steel plates are welded to get the Vertical Welding.

EX.NO.

THE OVERHEAD WELDING

Aim: To arc weld two metal piece of mild steel to get the Overhead Welding.

Tools Required: 1. 2. 3. 4. 5. 6. 7. 8.

Electrode Welding transformer Gloves Tong Chipping hammer Wire brush Welding shield Electrode holder

Procedure:  The mild steel plates to be joined are first cleaned.  The edge and surface to be welded are then filled or ground to get the required dimension.  Now the metal plates to be welded are placed in position on metal plate.  The welding electrode is held using an electrode holder and tack welds at two places are made such that the position of the plates do not change while welding.  Now the electrode is made to touch the metal plates and then electrodes is separated to leave a small gap. (3 to 4 mm) between its tips and the metal plates.  This initiates an arc.  Once the arc is initiated, the electrode is moved along the length of the metal pieces. For completing the welding process on one side.  Using tongs, the metal plates welded on one side is over turned. Welding is now carried out on the other side.  After welding, the plates are allowed to cool for some time. Using a chipping hammer, oxides are removed to complete the exercise.

RESULT: Thus the two mild steel plates are welded to get the Overhead Welding.

EX NO:

MAKING A GREEN SAND MOULD

AIM: To make a green sand mould using a given pattern. MATERIALS REQUIRED: 1. Pattern 2. Moulding sand 3. Parting sand. TOOLS REQUIRED: 1. 2. 3. 4. 5.

Moulding boxes Moulding board Shovel Trowel Rammers

GIVEN PATTERN (FIG: 1)

6.Sprue pin 7. Riser pin 8. Strike off bar 9. Draw spike 10. Vent rod

FINISHED MOULD (FIG: 2)

PROCEDURE: 1. The given pattern is placed on the moulding board. 2. Parting sand is applied over the pattern and the moulding board. 3. The drag is placed on the moulding board such that the pattern is at the center of the drag box. 4. The prepared moulding sand is filled and evenly rammed in the drag box. 5. Excess sand is removed using strike off bar. 6. The drag box is turned upside down. 7. The cope box is placed on the drag box. 8. The sprue pin and riser pin are kept at the respective positions. 9. The parting sand is applied at the parting plane 10. The green sand is filled and rammed in the cope box. 11. Vent holes are made in the cope box. 12. Sprue and riser pins are removed from the cope box. 13. The cope box is kept aside and the pattern is removed using draw spike. 14. The cope box is placed over the drag box.

RESULT: The green sand mould cavity is prepared as shown in fig (2) by using the given pattern as shown in fig (1).