mft - ii lab manual

43
1 1.0 STUDY OF DRILLING, MILLING, SHAPER, GRINDING AND GEAR HOBBING MACHINES 1. DRILLING MACHINE The drilling machine is one of the most important machine tools in a workshop. In a drilling machine holes may be drilled quickly and at a low cost. The hole is generated by the rotating edge of a cutting tool known as the drill, which exerts large force on the work clamped on the table. The different parts of a radial drilling machine have been illustrated in Fig (1.0). They are as follows: 1. Base, 2. Column, 3. Radial arm, 4. Drill head 5. Spindle speed and feed mechanism 1.1 BASE The base of a radial drilling machine is a large rectangular casting that is finished on its top to support a column on its one end and to hold the work table at the other end. In some machines T-slots are provided on the base for clamping work when it serves as a table. 1.2 COLUMN The column is a cylindrical casting that is mounted vertically at one end of the base. It supports the radial arm which may slide up or down on its face. An electric

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Anna University - Syllabus

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Page 1: MFT - II Lab Manual

1

1.0 STUDY OF DRILLING, MILLING, SHAPER, GRINDING AND

GEAR HOBBING MACHINES

1. DRILLING MACHINE

The drilling machine is one of the most important machine tools in a workshop.

In a drilling machine holes may be drilled quickly and at a low cost. The hole is

generated by the rotating edge of a cutting tool known as the drill, which exerts large

force on the work clamped on the table.

The different parts of a radial drilling machine have been illustrated in Fig

(1.0).

They are as follows:

1. Base,

2. Column,

3. Radial arm,

4. Drill head

5. Spindle speed and feed mechanism

1.1 BASE

The base of a radial drilling machine is a large rectangular casting that is

finished on its top to support a column on its one end and to hold the work table at

the other end. In some machines T-slots are provided on the base for clamping work

when it serves as a table.

1.2 COLUMN

The column is a cylindrical casting that is mounted vertically at one end of the

base. It supports the radial arm which may slide up or down on its face. An electric

motor is mounted on the top of the column, which imparts vertical adjustment of the

arm by rotating a screw passing through a nut attached to the arm.

1.3 RADIAL ARM

The radial arm that is mounted on the column extends horizontally over the

base. It is a massive casting with its front vertical face accurately machined to

provide guide ways on which the drill head may be made to slide. The arm may be

swung round the column. In some machines this movement is controlled by a

separate motor.

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1.4 DRILL HEAD

The drill head is mounted on the radial arm and drives the drill spindle. It

encloses all the mechanism for driving the drill at multiple speeds and at different

speed. All the mechanisms and controls are housed within a small drill head, which

may be made to slide on the guide ways of the arm for adjusting the position of drill

spindle with respect to the work.

1.5 SPINDLE DRIVE AND FEED MECHANISM

A constant speed motor is mounted at the extreme end of the radial arm, which drives

a horizontal spindle, which runs along the length of the arm, and the motion is

transmitted to the drill head through bevel gears. By train of gearing within the drill

head, the speed of the spindle may be varied. Through another train of gearing within

the drill head, different feeds of the spindle are obtained. In some machines, a vertical

motor is fitted directly on the drill head and through gearbox multiple speed and the

feed of the spindle can be obtained.

.

Fig (1.0) Radial drilling machine

1.Base, 2.Column, 3.Radial arm, 4.Motor for elevating the arm, 5.Elevating screw,

6.Guide ways, 7.Motor for driving the drill

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2. MILLING MACHINE

Milling is the process of removing metal by feeding the work piece through a

rotating multipoint cutter. Milling machine can be used for machining flat surfaces,

complex and irregular areas, surface of revolution, external and internal threads, gear

cutting, helical surface of cross sections.

The different parts of a Milling machine have been illustrated in Fig (3.0).

They are as follows:

1. Base

2.Column

3.Knee

4.Saddle

5.Table

6.Spindle

7.Arbor

Fig (2) shows the parts of a standard Milling Machine.

2.1. BASE:

It is the foundation of the machine and is that part upon which all parts are

mounted. It gives the machine rigidity and strength.

2.2. COLUMN:

It is the main supporting frame. The motor and other driving mechanisms are

contained with in it.

2.3 KNEE:

The knee projects from the column and slides up and down on its face. It

supports the saddle and table and partially supported by the elevating screw which

adjusts its height.

2.4. SADDLE:

The saddle supports and carries the table and is adjustable transversely on

ways on top of the knee. It is provided with graduations for exact movement and

operated by power or hand.

2.5. TABLE:

The table rests on ways on the saddle and travels longitudinally in a

horizontal plane. It supports the works piece, fixtures and all other equipments.

2.6. SPINDLE:

The spindle obtains its power from the motor through motors. Cutters are

mounted directly in the spindle nose.

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2.7. ARBOR:

The arbor is an accurately machined shaft for holding and driving the

arbor cutter. It is tapered at one end to fit the spindle nose and two slots to fit the nose

keys for locating and driving it.

Fig (2.0) MILLING MACHINE

1. Over arm 2.Arbor support 3.Arbor 4.Spindle 5.Table 6.Saddle 7. Knee

8. Elevating screw. 9. Column 10. Base

3. SHAPER

The shaper is a reciprocating type of machine tool intended primarily to produce

flat surfaces. These surfaces may be horizontal, vertical, or inclined.

The different parts of typical shaper are shown in fig (4.0).

The principal parts of a standard shaper are:

1. Base

2. Column

3. Cross rail

4. Saddle

5. Table

6. Ram

7. Tool head

1

23

4 5

6

7

8

9

10

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3.1 BASE

The base is the necessary bed or required for all machine tools. The base may be

rigidly bolted to the floor of the shop or on the bench according to the size of the

machine. It is so designed that it can take up the entire load of the machine and the

forces set up by the cutting tool over the work. It is made of cast iron to resist

vibration and take up high compressive load.

3.2 COLUMN

The column is a box like casting mounted upon the base. It encloses the ram

driving mechanism. Two accurately machined guide ways are provided on the top of

the column on which the ram reciprocates. The front vertical face of the column,

serves as the guide ways for the cross rail. The lid on the left side of the column may

be opened for inspection and oiling of the internal mechanism.

3.3 CROSSRAIL

The crossrail is mounted on the front vertical guide ways of the column. It has

two parallel guide ways on its top in the vertical plane that is perpendicular to the

ram axis. The table may be raised or lowered to accommodate different sizes of jobs

by rotating elevating screw, which causes the cross rail to slide up and down on the

vertical face of the column. A horizontal cross feed screw, which is fitted within the

cross rail and parallel to the top guide ways of the cross rail actuates the table to

move in a crosswise direction.

3.4 SADDLE

The saddle is mounted on the crossrail, which holds the table firmly on its top.

Crosswise movement of the saddle by rotating the cross feed screw by hand or power

causes the table to move sideways.

3.5 TABLE

The table is bolted to the saddle receives crosswise and vertical movements

from the saddle and cross rail. It is a box like casting having T-slots both on the top

and sides for clamping the work. In a universal shaper the table may be swiveled on a

horizontal axis and the upper part of the table may be tilted up or down.

3.6 RAM

The ram is the reciprocating member of the shaper. This is semi cylindrical in

form and heavily ribbed inside to make it more rigid. It slides on the accurately

machined dovetail guide ways on the top of the column and is connected to the

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reciprocating mechanism contained within the column. It houses a screwed shaft for

altering the position of the ram with respect to the work and holds the tool head at the

extreme forward end.

3.7 TOOLHEAD

The toolhead of a shaper holds the tool rigidly, provides vertical and angular

feed movement of the tool and allows the tool to have an automatic relief during its

return stroke. The vertical slide of the toolhead has a swivel base, which is held on a

circular seat on the ram. The swivel base is graduated in degrees, so that the vertical

slide is set perpendicular to the work or

at any desired angle.

Fig (3.0) Shaper

1. Table support,

2. Table,

3. Clapper box

4. Apron clamping bolts

5. Down feed hand wheel

6. Swivel base degree graduations

7. Position of stroke adjustment hand wheel

8. Ram block locking handle

9. Ram

10. Column

11. Driving pulley

12. Base

13. Feed disc

14. Pawl mechanism

15.Elevating screw.

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4. GRINDING MACHINE

Grinding is metal cutting operation performed by means of a rotating

abrasive wheel that acts as a tool. This is used to finish work pieces, which must

show a high surface quality, accuracy of shape and dimension.

4.1 SURFACE GRINDER

Surface grinding machines are employed to finish plane or flat surfaces.

The different parts of a horizontal spindle reciprocating table surface grinder

are shown in fig 4.0.

The principal parts of a horizontal spindle reciprocating table surface grinder are:

1. Base

2. Table

3. Wheel head

4.1.1 BASE

The base has a column at the back for supporting the wheel head. The

base also contains the drive mechanisms.

4.1.2 TABLE

The table is fitted to the saddle on carefully machined ways. It

reciprocates along ways to provide the longitudinal feed. T- slots are provided in the

table surface for clamping work pieces directly on the table or for clamping grinding

fixtures or a magnetic chuck.

4.1.3 WHEEL HEAD

The wheel head is mounted on the column secured to the base. It has

ways for the vertical slide, which can be raised or lowered with the grinding wheel

only manually by rotating a hand wheel to accommodate work pieces of different

heights and to set the wheel for depth of cut. Horizontal, cross wise movement of the

wheel slide with the wheel, actuated by hand or by hydraulic drive, accomplishes the

cross feed of the wheel. The grinding wheel rotates at constant speed; it is powered

by a special built- in motor.

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FIG 4.0. Horizontal spindle surface grinder

1. Column,

2. Wheel head

3. Table

4. Wheel

5. Saddle

6. Base

4.2. CYLINDRICAL CENTRE- TYPE GRINDER

Cylindrical centre- type grinders are intended primarily for grinding Plain

cylindrical parts, although they can also be used for grinding contoured cylinders,

fillets and even cams and crank shafts.

The different parts of a cylindrical centre- type grinder are shown in fig 5.1.

The principal parts of a cylindrical centre- type grinder are:

1. Base

2. Tables

3. Head stock

4. Tailstock

5. Wheel head

6. Cross-feed

4.2.1 BASE

The base or bed is the main casting that rests on the floor and supports

the parts mounted on it. On the top of the base are precision horizontal ways set at

right angles for the table to slide on. The base also houses the table- drive

mechanism.

4.2.2 TABLES

There are two tables – lower table and upper table. The lower table

slides on ways on the bed provides traverse of the work past the grinding wheel. It

can be moved by hand or power within desired limits.

The upper table that is provided at its center is mounted on the top of the

sliding table. It has T- Slots for securing the headstock and tailstock and can be

positioned along the table to suit the length of the work. The upper table can be

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swiveled and clamped in position to provide adjustment for grinding straight or

tapered work as desired.

4.2.3 HEADSTOCK

The headstock supports the work piece by means of a dead center and

drives it by means of a dog, or it may hold and drive the work piece in a chuck.

4.2.4 TAILSTOCK

The tailstock can be adjusted and clamped in various positions to

accommodate different lengths of work pieces.

4.2.5 WHEEL HEAD

The wheel head carries a grinding wheel and its driving motor is

mounted on a slide at the top and rear of the base. The wheel head may be moved

perpendicularly to the table ways, by hand or power, to feed the wheel to the work.]

4.2.6 CROSS-FEED

The grinding wheel is fed to the work by hand or power as determined

by the engagement of the cross – feed control lever.

FIG 4.2 Cylindrical centre- type grinder

1. Headstock,

2. Grinding wheel

3. Wheel head

4. Tailstock

5. Upper table

6. Lower table

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7. Base.

4.3 CENTRELESS GRINDER

Centreless grinding is a method of grinding exterior cylindrical, tapered and

formed surfaces on work pieces that are not held and rotated between centers. The

principal elements of an external centreless grinder are the grinding wheel, regulating

wheel and the work rest. Both the wheels are rotated in the same direction. The work

rest is located between the wheels. The work is placed upon the work rest, and the

latter, together with the regulating wheel, is fed forward, forcing the work against the

grinding wheel.

5.0 GEAR HOBBING

Gear Hobbing is a technique that is employed to create gear teeth configurations

that are ideal for use in a wide range of machinery components. In cases where the

gear hobbing takes place in a mass producing environment, gear hobbing is

accomplished through the use of precision gear hobbing machines that ensure that the

cut of each tooth on each gear produced meets the specifications set by the producer.

Generally, a gear hobbing machine will make use of a series of customized bits

that help to create the specific types of cutting and shaping necessary to create gears

that posses exactly the right pitch and circle to work in various types of equipment. A

customized bit is used for a particular size and type of gear hobbing, which helps to

ensure that the cuts that are made into the blank surface of the circle of metal are

relatively smooth and uniform.

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2.1 MACHINING A WORK PIECE BY DRILLING AND

REAMING USING A DRILLING MACHINE

AIM:

To machine a wok piece by drilling, reaming and tapping operations

using a drilling machine.

MATERIALS REQUIRED:

Cast iron circular plate – 100 X 10 mm

TOOLS REQUIRED:

1. Drilling machine

2. Steel Rule

3. Drills

4. Center punch

5. Reamers

6. Scriber

7. Tap sets

8. Hammer

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GIVEN WORK PIECE (FIG: 1)

FINISHED WORK PIECE (FIG: 2)

PROCEDURE:

1. The given work piece is marked and punched as per the given drawing.

2. Then the work piece is held firmly on the machine vice.

3. The drill bit of required drill size is held in drill spindle.

4. The machine is switched on and the drilling operation is done at the punched

positions.

5. Like drilling operation the reaming operation is done at already drilled holes by

using reamer.

6. The machine is switched off.

7. The work piece is measured and checked for all the dimensions as per the given

drawing.

RESULT:

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The given work piece as shown in fig(1) is subjected to drilling and reaming

operations to become a finished work piece as shown in fig (2).

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2.2 MACHINING V- BLOCK USING A SHAPER

AIM:

To machine V- block using a shaper

MATERIALS REQUIRED:

Cast iron cube – 78 X 78 X 78 mm

TOOLS REQUIRED:

1. Shaper

2. Hammer

3. Shaping tool

4. Steel Rule

5. Scriber

6. Try Square

7. Center punch

8. Spanner

GIVEN WORK PIECE (FIG: 1)

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FINISHED WORK PIECE (FIG: 2)

PROCEDURE:

1. The given work piece is held firmly in a shaper vice.

2. The shaping tool is set firmly on a tool head.

3. After adjusting the length of stroke and position of stroke the machine is

switched on.

4. By giving cross feed to the work piece through the table the shaping

operation is done on all the work surfaces.

5. The machine is switched off and the work piece is removed from the vice.

6. The work piece is marked and punched as per the given drawing.

7. Again the work piece is held on the vice and the machine is switched on.

8. By giving angular feed to the tool through the tool slide the V- shape is

machined.

9. The machine is switched off.

10. The work piece is removed and is measured & checked for all the dimensions as

per the given drawing.

RESULT:

The given work piece as shown in fig(1) is subjected to shaping operations to

become a finished work piece as shown in fig (2).

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2.3 MACHINING THE DOVE-TAIL SLOT ON A

WORK PIECE USING A SHAPER

AIM:

To machine a work piece and provide a Dove - Tail slot using a shaper

MATERIALS REQUIRED:

Cast iron cube – 80 X 80 X 80 mm

TOOLS REQUIRED:

1. Shaper

2. Hammer

3. Shaping tool

4. Steel Rule

5. Scriber

6. Try Square

7. Center punch

8. Spanner

GIVEN WORK PIECE FIG (1)

80

80

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FINISHED WORK PIECE FIG (2)

PROCEDURE:

1. The given work piece is held firmly in a shaper vice.

2. The shaping tool is set firmly on a tool head.

3. After adjusting the length of stroke and position of stroke of the ram, machine is

switched on.

4. By giving cross feed and longitudinal feed to the tool head the all sides of work

piece is machined as per the given drawing.

5. The machine is switched off and the work piece is removed from the vice.

6. The work piece is marked and punched as per the given drawing.

7. Again the work piece is held on the vice and the machine is switched on.

8. By giving angular feed to the tool through the tool slide the Dove-tail shape is

machined.

9. The machine is switched off.

10. The work piece is removed and is measured & checked for all the dimensions as

per the given drawing.

RESULT:

The shaping operation was done on the given work piece as shown in fig (1)

and Dove – Tail slot was provided as per the dimensions shown in fig (2).

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2.4 MACHINING A HEXAGONAL SHAPE FROM A ROUND

C.I.WORK PIECE USING A MILLING MACHINE

AIM:

To machine a hexagonal shape from a round C.I. work piece using a

milling machine.

MATERIALS REQUIRED:

Cast iron round blank 80 X 50 X 50 mm

TOOLS REQUIRED:

1. Milling machine

2. Plain milling cutter

3. Dividing head

4. Vernier caliper

5. Spanners

GIVEN WORKPIECE (FIG: 1)

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FINISHED WORK PIECE (FIG: 2)

CALCULATION:

Index crank movement =

where N= Number of sides

PROCEDURE:

1. The selected speed and feed of the machine is set.

2. The dividing head and the tailstock are bolted on the table after setting their axis

exactly perpendicular to the machine spindle.

3. The plain milling cutter is mounted on the arbor.

4. The work piece is mounted between the two centers by a mandrel.

5. The proper index plate is bolted on the dividing head and the positions of the

crank pin and the sector arms are adjusted.

6. The table is raised to give a required depth of cut.

7. The machine is started and the feed is applied to finish the first surface of the

blank.

8. After the end of the cut the table is brought to starting position and then the

blank is indexed for the next surface.

RESULT:

The given work piece as shown in fig (1) is subjected to milling

operation to become a finished work piece as shown in fig (2).

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2.5 CONTOUR MILLING OPERATION ON A WORK PIECE

USING A MILLING MACHINE

AIM:

To perform a contour milling operation on the given work piece using a milling

machine

MATERIALS REQUIRED:

Square aluminum plate-100x80x10

TOOLS REQUIRED:

1. Vertical Milling machine

2. Contour milling cutter

3. Outside Caliper

4. Steel Rule

5. Vernier Caliper

GIVEN WORK PIECE FIG (1):

100

80

100

100

40

30

30

9.5

26

7

30 20 205 5

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FINISHED WORK PIECE FIG (2)

PROCEDURE:

1. The given work piece is fixed in a table.

2. The form milling cutters are used for contoured milling.

3. The machine is switched on to revolve the cutter at the selected speed.

4. By giving Cross feed and longitudinal feed to the work table, the contour

operations are done respectively. The profile of the cutter coincides with that of the

work piece.

5. After the work piece is milled as per the given drawing machine is switched off.

6. The work piece is removed from the work table and all the dimensions are

measured and checked.

RESULT:

The contour milling operation was done on the given work piece as shown in fig

(1) as per dimensions shown in fig (2).

2.6 MACHINING A WORK PIECE USING A

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SURFACE GRINDING MACHINE

AIM:

To machine a work piece using a surface grinding machine.

MATERIALS REQUIRED:

Mild steel Flat - 80 X 50 X 10 mm

TOOLS REQUIRED:

1. Surface grinding machine

2. Vernier Caliper

GIVEN WORKPIECE (FIG: 1)

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FINISHED WORK PIECE (FIG: 2)

PROCEDURE:

1. The given work piece is held firmly on a magnetic chuck of a surface grinder.

2. The machine is started and the grinding wheel is allowed to revolve at a selected

speed.

3. After giving a depth of cut, the work piece is made to reciprocate under the

grinding wheel.

4. The table is fed axially between passes to produce a fine flat surface.

5. The process is repeated for grinding another side until the desired dimension is

achieved.

6. The dimensions are checked for its given dimensions using a vernier caliper.

RESULT:

The given work piece as shown in fig (1) is subjected to surface grinding

operation to become a finished work piece as shown in fig (2).

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2.7 MACHINING A WORK PIECE USING A CENTRE TYPE

CYLINDRICAL GRINDING MACHINE

AIM:

To machine a work piece using a cylindrical grinding machine.

MATERIALS REQUIRED:

Mild steel polished round rod - 25 X 150 mm

TOOLS REQUIRED:

1. Centre type cylindrical grinder

2. Vernier Caliper

3. Spanners

GIVEN WORKPIECE: (FIG 1)

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FINISHED WORK PIECE: (FIG 2)

PROCEDURE:

1. The given work piece is held between centers.

2. The machine is switched on and the grinding wheel is allowed to revolve at a

selected speed.

3. By giving longitudinal and cross feeds the work piece is ground for the required

dimensions.

4. The work piece is removed from the machine and is checked for the given

dimensions.

RESULT:

The given work piece as shown in fig (1) is subjected to external

cylindrical grinding operation by centre type cylindrical grinder to become a finished

work piece as shown in fig (2).

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2.8 MACHINING A WORK PIECE USING A

CENTRELESS GRINDING MACHINE

AIM:

To machine a work piece using a centreless grinding machine.

MATERIALS REQUIRED:

Mild steel polished round rod - 25 X 150 mm

TOOLS REQUIRED:

1.Centreless grinder

2. Vernier Caliper

3. Spanners

GIVEN WORKPIECE: (FIG 1)

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FINISHED WORK PIECE: (FIG 2)

PROCEDURE:

1. The given work piece is held between grinding wheel and regulating wheel and

supported on work rest.

2. The machine is switched on.

3. The grinding wheel and the regulating wheel are allowed to revolve at a selected

speed.

4. The work is fed forward and the grinding operation is done.

5. The work piece is removed from the machine and is checked for the given

dimensions.

RESULT:

The given work piece as shown in fig (1) is subjected to external cylindrical

grinding operation by centre less grinder to become a finished work piece as shown

in fig (2).

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2.9 MACHINING A COMPONENTS FOR

CLEARENCE FIT ASSEMBLY

AIM:

To machine the components for clearance fit assembly using lathe.

MATERIALS REQUIRED:

Mild steel polished round rod - 30 X 110 mm

TOOLS REQUIRED:

1.Turning tool

2. Parting off tool

3. Drill bit

4. Vernier caliper

5. Outside caliper

6. Inside caliper

GIVEN WORKPIECE: (FIG 1)

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FINISHED WORK PIECE: (FIG 2)

PROCEDURE:

1. The given work piece is held between rigidly in the chuck.

2. The single point cutting tool is set on the tool post.

3. The machine is switched on.

4. The straight turning and facing operation are done on the one half of the work

piece as per the given dimensions.

5. Then the drill bit of required drill size is held in tailstock and drilling is done for

the required depth in the work piece.

6. After finishing the one half of the work piece then another half is also finished as

per the drawing.

7. The machine is switched off.

8. The parting tool is fixed and by parting off operation the work piece is cut in to

two parts as per the dimensions.

9. The two parts are assembled for getting a clearance fit assembly.

RESULT:

The given work piece as shown in fig (1) is subjected to machining operations

to become a finished work piece as shown in fig (2).

2.10 MACHINING THE COMPONENTS FOR

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INTERFERENCE FIT ASSEMBLY

AIM:

To machine the components for interference fit assembly using lathe and

drilling machine.

MATERIALS REQUIRED:

1. Mild steel polished round rod - 30 X 110 mm

2. Mild steel plate – 50 X 50 X 10 mm

TOOLS REQUIRED:

1. Lathe machine

2. Drilling machine

3.Turning tool

4. Drill bit

5. Parting tool

6. Vernier caliper

GIVEN WORKPIECE: (FIG 1)

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FINISHED WORK PIECE: (FIG 2)

PROCEDURE:

1. The component – 1 is machined by straight turning and facing operations as

per the dimensions using a lathe.

2. The component – 2 is machined by drilling operation as per the dimensions

using a drilling machine.

3. After that both the components are assembled to get an interference fit

assembly.

RESULT:

The given work piece as shown in fig (1) is subjected to turing and drilling

operations to become a finished work piece as shown in fig (2).

2.11 MACHINING A SPUR GEAR USING A

GEAR HOBBING MACHINE

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AIM:

To machine a Spur Gear using a gear Hobbing machine.

MATERIALS REQUIRED:

1. Cast iron blank - 86 X 25 X 20 mm

TOOLS REQUIRED:

1. Gear Hobbing machine

2. Hob

3. Gear tooth vernier

4. Spanners

GIVEN WORKPIECE: (FIG 1)

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FINISHED WORK PIECE: (FIG 2)

PROCEDURE:

1. The given work piece is held firmly on the spindle of the gear

hobbing machine.

2. The Hob is set at an angle to he hob helix angle for cutting spur gear.

3. The change gears are set for the desired speed of work piece and

Hob and feed of the Hob.

4. The machine is switched on.

5. The work piece and Hob are allowed to rotate at the desired speed.

6. The hob or work piece is given full deph of cut equals to the tooth

depth.

7. The cutter is given feed for the full width of the work.

8. After machining all gear teeth on the blank the machine is switched

off.

9. The gear teeth are checked using a gear tooth vernier.

RESULT:

The given work piece as shown in fig (1) is subjected to gear generating

operation to become a finished work piece as shown in fig (2).