unit-i theory of metal cutting part-achettinadtech.ac.in/storage/13-12-21/13-12-21-09-03-16... ·...

1

UNIT-I

THEORY OF METAL CUTTING

PART-A

1. What is the function of chip breakers? (Nov/Dec 2005)

The chip breakers are used to break the chips into small pieces for removal, safety and to prevent

both the machine and work damage.

2. Name the factors that contribute to poor surface finish in cutting? (Nov/Dec 2007)

i. Cutting speed

ii. Feed

iii. Depth of cut

3. What is orthogonal cutting? (Nov/Dec 2007)

The cutting edge of tool is perpendicular to the work piece axis.

4. What are the functions of cutting fluids? (Nov/Dec 2006)

a) It is used to cool the cutting the tool and work piece.

b) It improves the surface finish as stated earlier.

c) It causes the chips to break up into small parts.

d) It protects the finished surface from corrosion.

e) It prevents corrosion of works and machine.

5. Give two examples of orthogonal cutting? (Nov/Dec 2005)

Turning, Facing, Thread cutting, parting off.

6. What are the four important characteristics of materials used for cutting tools? Nov/Dec

2007

a) hot hardness

b) Wear resistance

c) High thermal conductivity

d) Resistance to thermal shock

2

7. List the essential characteristics of Cutting Fluids? (Nov/Dec 2009)

a) High heat absorbing capacity

b) It should be odorless.

c) High flash point.

d) It should be non-corrosive to work and tool.

8. Name the various cutting tool materials? (Nov/Dec 2010)

a) Carbon tool steel

b) High speed steel

c) Cemented carbides

d) Ceramics and

e) Diamonds.

9. What are the factors responsible for build-up edge in cutting tools? (Apr/May-2011)

a) Low cutting speed

b) Small rake angle

c) Coarse feed

d) Strong adhesion between chip and tool face.

10. What is electro-chemical wear in tools? (Nov/Dec 2005)

An electrical cutting cell is provided having an anodic conductive cutting tool and a catholic

conductive work piece connected to a dc supply, the lubricant contains palatable reducing agents.

The lubricant is located to bathe the contacting interface b/w the cutting tool and work-piece to

constituent an electrolyte.

11. How do you classify tool wear? (Nov/Dec 2006) (Nov/Dec 2013)

a) Frank wear or crater wear

b) Face wear

c) Nose wear.

12. Define tool life? (Nov/Dec 2007)

3

It is defined as the time elapsed b/w two consecutive tool re-sharpening. During this period

the tool source effectively and efficiently.

13. Compare orthogonal and oblique cutting? (May/Jun-2009) (Nov/Dec 2013)

S.No Orthogonal cutting Oblique cutting

1. The cutting edge of the tool

Remains normal to the direction

of feed.

The cutting edge of the tool is

Inclined at an angle to the

direction of tool feed

2. The cutting edge clears the

width of the work piece on

either ends

The cutting edge may or

may not clear the width of

the work piece

3. The chip coils in a tight flat spiralThe chip flows sideways in

a long curl

14 .What are objectives and functions of cutting fluids? ( Apr/May 2011)

The Objectives of cutting fluids,

• Flooding,

• Jet application,

• Mist application.

The Functions of cutting fluids are,

• To cool the tool,

• To cool the work piece,

• To lubricate and reduce friction,

14. Briefly explain the effect of rake angle during cutting? (Nov/Dec-2006),(May/Jun-

2009),(Apr/May-2011)

During the cutting process, the chip curling is the amount of chip bend depends upon this angle. If the

side rake angle is larger, the amount of power required to cut the bend the chip will increase. Hence it

produces better surface finish.

15. List the various materials removal process? (Nov/Dec 2010)

a) Non-Cutting processor Chip less process

4

b) Cutting processor Chip process.

16. How chip formation occurs in metal cutting? ( Nov/Dec 2005 )

During machining, the cutting tool exerts a compressive press on the work piece. The material of

the work piece is stressed beyond its yield point under the compressive force. This causes the

material to deform plastically and shear off. The plastic flow takes place in a localized region

called shear plane.

The shear plane extends from the cutting obliquely up to the uncut surface ahead of tool. The

sheared material begins to flow along the cutting tool face in the form of small pieces called chips.

The compressive force applied to form the chip is called cutting force. The cutting forces, heat and

abrasive wear are the basic features of the metal cutting process.

PART B

1) Describe an expression for the determination of shear angle in orthogonal metal

cutting? (Nov/Dec 2005)

(Refer text book –Vijayaraghavan- Chapter -1, Sec-1.5, page number : 1.10 )

2) The following cutting speed of cutting time observations have been noted in a

machining process.calculate (Nov/Dec 2005)

1) ‘n’ and C.

2) Recommend the cutting speed for a desired tool life of 60 minutes.

Cutting speed 25m/min 35m/min

Cutting time, 90min 20min

(Refer text book –Vijayaraghavan- Chapter -1, page number : 1.46)

3) Explain the types of chip formed during machining process (Nov/Dec 2006)

5

(Refer text book –Vijayaraghavan- Chapter -1, Sec-1.6.1, page number : 1.13)

4) Using merchant’s circle diagram ,derive the expression for estimating the cutting force

during machining. Mention the assumptions made? (Nov/Dec 2006)


5) a)What is tool life? (Nov/Dec 2006)

b) Describe the forms of wears on the cutting tool with neat sketches?



6) Explain the conditions that promote the formation of the following types of chip:

a)continuous chip without buildup edge .

b) continuous chip with buildup edge.

c) discontinuous chips. (Nov/Dec 2007) (Apr/May 2010)


7) a)Define the various tool parts of a single point cutting tool with a neat sketch?

b)What are the standard angles of cutting tool? illustrate with an example. (Nov/Dec 2007)


8) What is orthogonal rake system? show the ORS of tool analysis with the help of

6

sketch. (Nov/Dec 2008)

(Refer text book –Vijayaraghavan- Chapter -1, Sec-1.5, page number : 1.10)

9) What is the use of a chip breaker? discuss the various types of chips produced during metal

machining process. (Nov/Dec 2008)


10) Explain the geometry of a single point tool with suitable sketches. (May/Jun 2009)


11) a)Explain the basic actions of cutting fluids? (May/Jun 2009)


12) a)State the parameters that influence the life of tool and discuss? (Apr/May 2010)


13) a)What is meant by orthogonal cutting cutting and oblique cutting?

b)Explain “Merchant force circle”along with assumptions? (Apr/May 2010)


14) a)Describe the mechanim of metal cutting?

b)Discuss the various types of chips produced during metal machining?(Apr/May 2011)


7

15) a) List the various tool material used in industry. State the optimum temperature of each of the

tool material? (Nov/Dec 2010)


16) In a orthogonal cutting operation of a work piece of width 2.5 mm, the uncut chip thickness of

0.25mm and the tool rake angle zero degree. It was observed that the chip thickness was

1.25mm.The cutting force was measured to be 900N and the thrust force was found to be 810N.

a)Find the shear angle.

b)If the coefficient of friction between the chip and the tool was 0.5,what is the

machining constant Cm? (Nov/Dec 2010)


17) a)Describe the different types of chips with neat sketches?

b)Mention the functions of cutting fluids? (Nov/Dec 2010)



18) a)Discuss about orthogonal cutting?

b) Explain various cutting tool materials? (Apr/May 2011)



19.Write briefly about different cutting tool materials used in metal cutting .(Nov/Dec 2013)


20.Write a short note on cutting fluids in metal cutting . (Nov/Dec 2013)


21.Write a short note on different tool wear mechanism in metal cutting. (Nov/Dec 2013)


8

UNIT-2

CENTRE LATHE AND SPECIAL PURPOSE LATHES

1. What are the functions of feed rod & lead screw? (Nov/Dec 2005)

FEEDROD:

It is used to guide the carriage in a straight line when it is moves along the bed

LEADSCREW

It is used to move the carriage while thread cutting operation is carried out. It also

ensures the proper speed of work relative to the tool for thread cutting operation.

2. Why was power chucks developed? (Nov/Dec 2005)

Power chucks primarily developed for the application as work holding devices for

automatic machines, numerical control& CNC machines.

3. What is the advantage of automatic lathe? (Nov/Dec 2006)

1. Mass production of identical parts.

2. High accuracy is maintained.

3. Production time is less

4. The bar stock is fed automatically

4. Calculate the power required for cutting a steel rod of 50mm in diameter at 200 rpm

assume cutting force of 160 kg ? ( Nov/Dec2006)

P=FXv

P=Fx πdn/1000

P=160 X 9.81X 5X 50X 200/(1000 X 60)

P=821.8kw

5. Why is it essential that the cutting point of the tool should be level with the spindle center

while machining taper on a work piece? (Nov/Dec 2007)

9

It is done to avoid eccentric taper

6. What is the difference between ram type turret lathe & saddle type turret lathe?

(Nov/Dec 2007) (Apr/May2010) (Apr/May2011)

7. What is the purpose of mandrel how many types of mandrel is commonly

used? (Nov/Dec 2008)

Mandrel are used for holding hallow work piece

1. Plain mandrel

2. Collar mandrel

3. Cone mandrel

4. Special mandrel

5. Step mandrel

6. Expansion mandrel

7. Gang mandrel

8. What is the advantage of using collect chuck? (Nov/Dec2008)

1. Job setting will be easy and quick

2. Heavy cut can be taken

9. Mention four different types of chucks used in machine shop? (May/Jun2009)

1. 3 jaw chuck

2. 4 jaw chuck

3. magnetic chuck

10. What is rake angle? What is the affect of nose radius in tools? (May/Jun2009)

CAPSTAN LATHE TURRET LATHE

1. Turret head is mounted on

a ram which is slides over

the saddle

2. Shorted work piece can

be machined

3. Turret head can be moved

manually

1. Turret head is directly

mounted on a saddle but

it is slides on the bed

2. Longer work piece can

be machined

3. Turret head cannot be

moved manually

10

The angle between the tool face and the line parallel to the base of the tool is known as

side rake angle. It is used to control chip flow.

11. State different method of taper turning? (Apr/May 2010) (Apr/May 2011)

a)Form tool method

b) Tail stock set over method

c) Compound rest method

d) Taper turning attachment method

12. Explain following parts of lathe? 1.lathe bed 2.carriage (Nov/Dec10)

LATHE BED:

Bed is the base of the machine it carries a head stock on its left end and tail stock on it

right end carriage is mounted on middle of the bed

CARRIAGE:

Carriage is a moving part that’s slides over the guide ways between the head stock and

tail stock

13. What is an apron? (Nov/Dec10)

It is an integral part of several gear , levers and clutches which are mounted with the

saddle for moving the carriage along with lead screw while thread cutting.

14. What are the various thread cutting method? (Apr/May2011)

1. Reversing the machine

2. Making the lathe parts

3. Using a chasing dial

4. Using thread chaser

15. What is Swiss type automat? (Apr/May2011)

The work is fed against the tool the head stock carrying the bar stock moves back and forth

for providing the feed movement in the longitudinal direction

16. Name the specifications of a centre lathe (Nov/Dec 2013)

1.The length of bed 2. Maximumdistance between dead and live centres.3.Type of bed

i.e straight ,semi gap or gap type. 4.The height of centres from bed. 5.swing over bed 6.swing over

11

cross slide .7 width of bed 8.spindle bore 9.spindle speed 10.H.P.of main motor and rpm.

11.Number of spindle speeds.12.apindle nose diameter 13.Feeds. 14.Floor space required.

17.What is the need of Automatic Lathe (Nov/Dec 2013)

1. Mass production of identical parts.

2. High accuracy is maintained.

3. Production time is less

4. The bar stock is fed automatically

PART-B

1 . what is lathe carriage ? Explain the various parts of a lathe carriage with a

neat diagram. (Nov/Dec 2005)


2. Enumerate the purpose of various attachment used on a centre lathe. (Nov / Dec 2005)


3. What is a Swiss-type automatic screw machine ? How it functions and what are

its main application? (Nov/Dec 2005) (Nov/Dec 2013)


4. Calculate the time taken for one complete cut on a work piece of 500mm long and 50mm

diameter .the cutting speed is 30 m/min and feed rate is 0.5mm/revolution. (Nov/Dec 2006)


12

5. Describe the working principle of multi –spindle automatics . Given its advantages and

application. (Nov/Dec 2006)


6. Explain the construction and working principle of a lathe with sketch. (Nov/Dec 2006)


7. Describes some of the methods and equipments for holding work on a lathe. (Nov/Dec 2007).


8. Explain any four commonly used attachments on lathe. (Nov/Dec 2007).


9. Explain the principle of working of the single spindle automatic machine. (Nov/Dec 2007).


10. Describe with a neat sketch a turret automatic screw machine. (Nov/Dec 2007).


11. Explain the neat sketch the various methods of turning a taper. (Nov/Dec 2008).


13

12. Write down the differences between a capstan and a turret lathe. (Nov/Dec 2008) (Nov/Dec 2013)


13. Explain the thread cutting operation in a lathe with a neat sketch. Also make a note on

knurling , grooving and forming operations in a lathe. (May/Jun 2009).


14. Discuss the feature of ram type and saddle type turret. (May/Jun 2009).


15.Discuss the main parts of a turret lathe.(Apr/May 2010).


16. What is meant by ‘Tool layout’ of a turret lathe. (Apr/May 2010).


17. Name the various lathe accessories. How does a four jaw chuck differ from a three jaw

chuck. (Apr/May 2010).


18. Discuss about the bar feed mechanism. (Apr/May 2011)


19. Draw sketches of steady and follower rests and brief their applications (Apr/May 2011).

14


20. Explain the bar feeding mechanism used in turret lathe while machining bar stock. (Apr/May

2011).


21. Describe the features of swiss type automatic screw machine. (Apr/May 2011).


22. Explain the following with an neat sketch (Nov/Dec 2013)

a. Tapper tuning by swiveling the compound rest

b. Tapper turning attachment method

c. Tapper turning with tailstock set over method (Nov/Dec2010)


23. Describe the holding devices in an lathe. (Nov/Dec2010)


24. Mention the specification of lathe with a neat sketch (Nov/Dec2010)


25. Explain the various tapper turning method .(Apr/May2011).


26. Discuss about special attachments of lathe.(Apr/May2011)


15

UNIT-3

OTHER MACHINE TOOLS

1.) What is shell mill? (Nov/Dec 2005)

A shell mill is a large type of face or end mill that mounts on to an arbor, rather than having an

integral shank. Typically, there a hollow or recess in the centre of the shell mill for mounting hardware

onto a separate arbor.

2.) Mention the operations performed by a planer? (Nov/Dec 2005)

I. Planing horizontal surface.

II. Planing of an angle.

III. Planing vertical surface

IV. Planing curved surface.

3.) What is hydraulic shaper with mechanical shaper? (Nov/Dec 2006)

4.) Difference between up milling and down milling? (Nov/Dec 2006),(May/Jun-2009),(Apr/May-

2011) (Nov/Dec 2013)

Hydraulic shaper Mechanical shaper

I. Smooth cutting operation.

II. Changing of cutting speed is

easy

III. Higher cutting to return ratio

can be obtained.

IV. Stroke length can easily

adjusted without stopping the

machine.

Rough and noisy cutting operation.

Changing of cutting speed is difficult.

Lower cutting to return ratio.

Change of stroke length is not

possible without stopping the

machine.

16

Up milling Down milling

Direction of travels :

Cutter rotates against the direction of

travel of work piece.

Cutter rotates in the same direction of

a travel of work piece.

Chip thickness: Minimum at the

beginning of cut greech max when the

cut terminates.

Minimum at the beginning greeches

min at terminates.

Increase from zero to max Decrease from max to zero per tooth.

5.) Why is sawing a commonly used process? (Nov/Dec-2005)

1. Easy handling of machines and spindle construction.

2. Fast operation and cost of machinery is less.

6.) Under what condition planning operation would be preferred over other machining process

like milling, broaching, shaping, etc? (Nov/Dec-2007)

In planer, the work piece mounted on the table reciprocates but the tool is stationary. A single point

cutting tool is used for machining the work surface. This tool is always fitted vertically the tool holder

which moves on a cross-rail while feeding. Planer is mainly used for machining large and heavy work

piece. The machined surface may be horizontal, vertically or inclined surface.

7.) What are the common work holding device used on milling machine? (Nov/Dec-2007)

I. “V” blocks.

II. Machine vises.

III. Milling fixture.

IV. Dividing heads.

8.) Difference between vertical shaper and slotter ? (Nov/Dec-2008)

Vertical shaper slotter

I. Vertical shaper generally fitted

with rotary table to machine

curved surfaces.

II. Rotary table along with tools

The slides are fitted.

Slides will move to perform slotting.

17

will move.

III. Vertical shaper is not fixed in

the vertical plane.

Slotter is fixed in the vertical plane.

9.) Difference between drilling and tapping? (Nov/Dec-2008)

Drilling Tapping

I. Drilling is the process of producing

hole on the work piece by using a

rotating cutter.

II. Different shapes of holes can be

made.

Tapping is the process used for making

internal threads in a machine component

by a tool called tap.

Internal thread can be cut in existing

drilled holes.

10.) What do you know about straight fluted and fluted drill? (May/Jun- 2009)

The reamer with helical flutes provides better smooth shear cutting action and provides better

surface finish. The pitch of the flutes is made un even to reduce vibration.

11.) How do you classify milling cutter? (Nov/Dec-2010)

a) Milled tooth cutters

b) Form relived cutters

According to the type operation

a) Plain milling cutter, Wood ruff key slot milling cutter

b) Side milling cutter, Fry cutter, Form milling cutter

c) End milling cutter

d) Angle milling cutter

e) T-slot milling cutter

f) Slitting saws

12.) Define broaching? (Apl/May-2010), (Nov/Dec-2010)

It is the process of machining a surface with a special multipoint cutting tool is called broach which

has successfully higher cutting edge in a fixed path

18

13.) Application of broaching machines ? (Apl/May-2011)

1. Straight & helical slots

2. External surface of various shape

3. External & internal toothed gears

14.) Define cutting speed, feed , machining time? (Nov/Dec-2010)

CUTTING SPEED:

It is a peripheral speed of a point of the surface of the drill in contact with the work piece. it is

expressed m/mins

FEED:

It is the distance of a drill moved in to the work at each revolutions of the spindle it is expressed

mm/rev

MACHINING TIME:

The time taken to complete the machining process without considering the idle time of machine

is known as machining

15.) Difference between planner and shaper ? (Apr/May 2011)

PLANNER SHAPER

1.tool is stationary and work

reciprocates

2.This machine is used for

machining large and heavy work

piece

1. work is stationary and tool

reciprocates

2.This machine is used for

machining medium and

small work piece

16.) Difference between drilling and reaming? (Apr/May 2011)

17.Draw the nomenclature of standard drill (Nov/Dec 2013)

DRILLING REAMING

1. Drilling is the process of

producing hole on the work

piece by using a rotating cutter.

1.Reaming is the operation of finishing

and sizing hole which is already drilled

while the work is revolved at slow speed

19

PART-B

1) Describe with a neat sketch , the quick return mechanism of a shaper?(Apr/May 2008)

(Refer text book –Vijayaraghavan- Chapter -3, Sec-3.1.9.3, page number : 3.10)

2) State the advantage of Ward-leonard drive? (Nov/Dec 2007)


3) Explain the hydraulic drive of a horizontal shaper with neat sketchs?( Nov/Dec2008)

(APR/MAY11)


4) State the advantages and limitations of broaching? (Nov/Dec 2007)


5) Explain with a sketch "Fast and Loose pulleys" quick return mechanism of table?(Nov/Dec

2007)


20

6) Explain the methods of holding milling cutters? (Nov/Dec 2007)


7) Explain Simple indexing, Compound indexing and differential indexing with suitable

example? (Nov/Dec 2007)


8) Explain index milling , screw thread milling and end milling operation ?(Apr/May-2008)


9) Differentiate the up milling from down milling process ? (Apr/May-2008)


10) Explain the various drill holding device ? (Apr/May2008)


11) With neat sketch describe the construction and working of a slotter? (Nov/Dec 2006)


12) List difference between shaper and planner?(Nov/Dec 2006), (Nov/Dec 2005) (Nov/Dec 2013)


13) Sketch and explain the working principle of upright drilling machine?(Nov/Dec 2006)


14) Write short notes on expanding hand reamers and adjustable machine reamers?

(Nov/Dec 2006)


15) Explain construction & working principle of continuous broaching machine?

(Nov/Dec2006)


21

16) Describe the basic types of milling cutters and milling operation ? (Nov/Dec 2005)


17) Explain main parts of a band saw and hand saw? (Nov/Dec 2005) , (Apr/May 2011)


18) Sketch a twist drill. write down its main parts and their function? (Nov/Dec 2008)


19) Write shorts notes reaming and boring operation? (Nov/Dec 2008)


20) With the help of a neat sketch, discuss the working of continuous surface broaching machine and

write its advantages and limitation? (Nov/Dec 2008)


21) With simple sketches explain the feature of the major element of twist drill?(Nov/Dec2008)


22) Explain different types of milling cutters? (Nov/Dec 2008)(Apr/May 2011)


23) Make a note on different types of work holding devices used in a slotting machine?

(Nov/Dec 2008)


24) Explain the different types table drive and feed mechanism in planning

machine ? (Nov/Dec 2008)


25) What is the operation performing on a drilling machine? (Apr/May 2010) (Nov/Dec 2013)


26) Explain different types of drilling machines with their specific features? (Apr/May 2010)


22

27) Discuss the common work holding devices used in shaper, slotter and planners?

(Apr/May 2010)


28) Sketch the Quick return mechanism .write its main parts & functions? (Apr/May 2011)


29) How will you cut the following types of surfaces on milling machines?(Apr/May 2011)

a. Flat surfaces b.Slots and splines.


30) With the help of a neat sketch discuss the working of a surface broaching

machine ? ( Apr/May 2011)


31) Describe the principle operation of a shaper with a neat sketch? ( Nov/Dec 2010)


32) Describe the working of a crank and slotted link mechanism? ( Nov/Dec 2010)


33) With a neat sketch explain the column and knee type milling machine and name its main

parts ? ( Nov/Dec 2010)


34) With a line diagram, describe the radial drilling machine ? (Nov/Dec 2010)


35) Discuss the various hole making processes ? (Apr/May 2011)


36) Discuss push and pull type broaching machine with neat sketch ? (Apr/May 2011)


unit-i theory of metal cutting part-achettinadtech.ac.in/storage/13-12-21/13-12-21-09-03-16... ·...

Documents