UNIT 1.

2 MARKS

1) Classify the process of metal shaping?

The process of metal shaping is classified into two types

Non cutting shaping process

Cutting shaping process

2) Explain the non cutting shaping process ?

The metal is shaped under the action of force , heating or both . Since there is no cutting of metal , chip formation will so be there . So it is called as non cutting process.

Example: Forging , Drawing , Rolling etc.

3) Explain the cutting shaping process ?

The required shape of the metal is obtained by removing the unwanted material from the work piece in form of chips is called as cutting process.

Example: Milling , Boring , Drilling etc.

4) Classify the relative motion between the work piece and cutting tool ?

Rotation of work piece against the tool. Ex: Turning. Rotation of tool against the work piece. Ex: Drilling. Linear moment of work piece against the tool. Ex: Planner. Linear moment of tool against the work piece. Ex Shaper.5) What are all different types of cutting tools ?

Single point cutting tool. Multiple point cutting tool.6) Mention various parts of single point cutting rod ?

Shank

Face

Flank

Base

Nose

Cutting edge

7) Classify the various angles in cutting tool ?

Back rake angle Side rake angle End relief angle Side relief angle Side cutting angle End cutting angle8) What is tool signature ?

The various angles of tools are mentioned in a numerical number in particular order . That order is known as tool signature .

9) What is the effect of back rake angle and mention its types ?Back rake angle of a tool increases the strength of cutting tool and cutting action .

It is classified into two types

Positive rake angle

Negative rake angle

10) What is rake angle ? What is the effect of nose radius in tools ?

The angle between the tool face and line parallel to the base of the tool is known as rake angle . It is used to control chip flow .

11. What is clearance angle? Mention its types ?

Ans: These are the slopes ground downwards from the cutting edges. The clearance angle can be classified as :

a) Slide relief angle

b) End relief angle

12. Explain the term Nose radius?

Ans : It is the joining of the side and end cutting edges by means of a small radius in order to increase the tool life and better surface finish on the work piece.13. What are all the conditions for using positive rake angle?

Ans. a) To machine the work hardened materials

b) To machine low strength ferrous and non ferrous metals

c) To turn the long shaft of small diameters

d) To machine the metal below recommended cutting speeds

e) To machine the work piece using small machine tools with low horsepower

14. When will the negative rake angles be used?

Ans. a) To machine high strength alloys

b) To machine tools which are more rigid

c) The feed rates are high

d) To give heavy and interrupted cuts

15. Name the factors that contribute to poor surface finish in cutting?

Ans. a ) Cutting speed

b) Feed

c) Depth of cut

16 . Classify the types of metal cutting process?

Ans. The metal cutting processes are mainly classified into two types :

a) Orthogonal cutting process 2 dimensional cutting

b) Oblique cutting Process 3 dimensional cutting

18. What is orthogonal cutting?

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

19 . Give two examples for orthogonal cutting?

Ans. Turning , Facing , thread cutting and parting off

20) Define Oblique cutting?

Ans. The cutting edge is inclined at an acute angle with normal to the cutting velocity vector is called oblique cutting.

21. What is shear plane?

The material of 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.

22. What is cutting force?

The sheared material begins to flow along the cutting tool face in the form of small pieces. The compressive force applied to form the chip is called cutting force.

23. What is chip and mention its different types?

The sheared material to flow along the cutting tool face in the form of small pieces is called chip. Chips are classified into three types:

a) Continuous chip.

b) Discontinuous chip.

c) Continuous chip with built up edge.

24. When will be continuous chip formed?

The following factors favour the formation of continuous chip.

i. Ductile material

ii. Smaller depth of cut

iii. High cutting speed

iv. Large rake angle

v. Sharp cutting edge

vi. Proper cutting fluid

vii. Low friction between tool face and chips.

25. What will be the favourable factors for discontinuous chip formation?

a) Machining of brittle material

b) Small rake angle

c) Higher depth of cut

d) Excess cutting fluid

e) Low cutting speeds

f) Cutting ductile material with low speed and small rake angle of the tool.

26. What are the favourable factors for continuous chip with built up edge?

a) Low cutting speed.

b) Small rake angle.

c) Cutting feed.

d) Strong adhesion between chip and tool face.27.What is chip thickness ratio?

The ratio of chip thickness before cutting to chip thickness after cutting is called chip thickness ratio.

Chip thickness ratio, r= = 28. What is chip reduction co-efficient?

The reciprocal of chip thickness ratio is called chip reduction co_efficient.

k= 29. What is the function of chip breakers?

The chip breakers are used to break the chips into small pieces for removal, safety and to prevent both the machine and work damage.

30. What are the difficulties involved due to long and continuous chip?

During machining, long and continuous chip that are formed at high cutting speed will affect machining. It will spoil tool, work and machine. These chips are hard, sharp and hot. It will be difficult to remove metal and also dangerous to safety.

31. Classify the different types of chip breakers? Step type Groove type

Clamp type

32. What are cutting forces acting on the cutting tool?

Feed force,Fx Thrust force,Fy Cutting force,Fz33. What are the assumptions made in merchant circle?

The chip formation will be continuous without the built up edge

During cutting process, cutting velocity remains constant.

The cutting tool has the sharp cutting edge so that it does not make flank contact to the work piece.

34. What is metal removal rate?It is defined as the volume of metal removed in unit time.it is used to calculate the time required to remove specified quantity of material from the work piece.35. What are the assumptions made in lee and shaffers theory?

The work ahead of the tool behaves as the ideal plastic mass

There exist a shear plane which seperates the chip and work piece

No hardening in the chip occurs

36. Explain the total energy of the cutting process?Total energy per unit volume is approximately equal to the sum of following energies.

Shear energy per unit volume in shear plane.

Friction energy per unit volume in tool face.

Surface energy per unit volume due to the formation of new surface area in cutting.

Momentum energy per unit volume due to the change in momentum associated with the metal as it crosses shear plane.

37. Define machinability of metal.

Machinability is defined as the ease with which a material can be satisfactorily machined.38. What are the factors affecting the machinability?

Chemical composition of the work piece material.

Microstructure of the work piece material.

Mechanical properties like ductility,toughness,etc.,

Physical properties of the workpiece material.

The method of production of work materials.39. What are the tool variables affecting the machinability?

Tool geometry and tool material.

Nature of engagement of the tool with the work.

Rigidity of the tool.

40. What are the machine variables affecting the machinability?

Rigidity of the machine.

Power and accuracy of the machine tool.

41. How can be machinability evaluated?

Tool life per grind

Rate of removal per tool grind

Magnitude of cutting forces and power consumption

Surface finish

Dimensional stability of finished work Heat generated during cutting

Ease of chip disposal

Chip hardness, shape and size

42. Mention the advantages of high machinability?

Good surface finish can be produced

High cutting can be used

Less power consumption

Metal removal rate is high

Less tool wear

43. What is machinability index?

It is the comparison of machinability of different material to standard material. US material standard for 100% machinability is SAE 1112 hot rolled steel.Machinability index,I=(cutting speed of metal investigated for 20 minutes tool life)/(cutting speed of the standard steel for 20 minutes tool life)44. Classify the tool wear.

Flank wear or crater wear

Face wear

Nose wear

45. What is electro chemical wear in tools?

An electrical cutting cell is provided having an anodic cutting tool and a catholic conductive work piece connected to a DC current supply; the lubricant contains palatable wear reducing agents. The lubricant is located to bathe the contacting interface between the cutting tool and workpiece to constitute electrolyte. The cutting tool is moved into and along cutting contact with the work piece while current flows there between to electrochemically deposit the wear reducing agents on at least the contacting interface to reduce cutting tool wear and improve ease of mass removal.46. How tool life is defined?

Tool life is defined as the time elapsed between two consecutive tool re sharpening. During this period the tool serves efficiently and effectively.

47. Write Taylors tool life equation.

Taylors tool life equation, VTn=C.Where, V= Cutting speed in m/min.

T= Tool life in min.

C= Constant

n= Index depends upon tool and work.

48. What are the ways of representing the tool life?

Volume of the metal removed per grind.

Number of work piece machined per grind.

Time unit.

49. What are the factors affecting tool life?

Cutting speed.

Feed and depth of cut.

Tool geometry.

Tool material

Cutting fluid

Work material

Rigidity of work, tool and ,machine

50. What are the factors considered for the selection of cutting speed?

Tool life

Properties of materials being machined.

Rate of feed

Depth of cut

Tool geometry

Cutting fluid used

Types of machining process

Surface finish to be obtained51. What are the factors to be considered for the selection of tool material? Volume of production

Tool design

Type of machining process

Physical and chemical properties

Rigidity and condition of machine.

52. What are the four important characteristics of materials used for cutting tools?

Hot hardness

Wear resistance

High thermal conductivity

Resistance to thermal shock

Easy to grind and sharpen.

Low mechanical and chemical affinity for the work material.

53. Name the various cutting tool materials.

Carbon tool steel

High speed steel

Cemented carbides

Ceramics

Diamonds

54. What are the functions of cutting fluids?

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

It lubricates the cutting tool and thus reduces the co-efficient of friction between tool and work.

It improves the surface finish as started earlier.

It causes the chips to break up into small parts.

It protects the finished surface from corrosion.

It washes away the chips from the tool. It prevents the tool from fouling.

It prevents corrosion of work and machine.

55. What are the factors responsible for built-up edge in cutting tools?

During cutting process, the interface temperature and pressure are quite high and also high friction between tool chip interfaces causes the chip material to weld itself to the tool face near the nose. This is called built up edge.

56. List the essential characteristics of a causing fluid.

It should have good lubricating properties to reduce frictional forces and to decrease the power consumption.

High heat absorbing capacity.

It should have a specific heat, high heat conductivity and high film co-efficient.

High flash point.

It should be odourless.

It should be non-corrosive to work and tool.

57. Briefly differentiate between orthogonal cutting and oblique cutting?

Sl. noOrthogonal cuttingOblique cutting

1The cutting edge of the tool is perpendicular to the cutting velocity vector.The cutting edge is inclined at an acute angle with the normal to the cutting velocity vector.

2The chip flows over the tool face and the direction of chip-flow velocity is normal to the cutting edge.The chip flows on the tool face making an angle with the normal on the cutting edge.

3The cutting edge clears the width of the work piece on either ends.(i.e. no side flow)The cutting edge may or may not clear the width of the work piece.

4The maximum chip thickness occurs at its middle.The maximum chip thickness may not occur at the middle.

59. Why can relief/clearance angles never be zero or negative?

It relief/clearance angles are zero or negative the tool will rub against the job. So, tool will get overheated and cutting is not proper. So, you will get a poor surface finish.

60. What do you understand by negative rake angle?

The slope given away from the cutting edge is called negative rake angle.

61) When will the diamond tools be used?

Diamond is hardest material. It is used for machining very hard materials such as glass, plastics, ceramics, etc.

62) What are the advantages of increasing nose radius?

If the nose radius increases, the strength of cutting tool is increased and it is used on castings and cast iron, where the cuts are interrupted.

63) Give the equations of velocity of chip and velocity of shear in terms of cutting velocity, rake angle and shear angle?

Velocity of chip, Vc =

Velocity of shear, Vs = 64) Calculate the power required for cutting a steel rod of 50mm in diameter at 200rpm. Assume cutting force of 160kg.

Power required = Fc V

= Fc

= (160 9.81)

= 821.8 kW.65) Write down the shear angle in terms of chip thickness and rake angle of the tool?

Shear angle, = tan-1 66) What is the composition of high speed steel?

High speed steel contains

Tungsten 18%, Vanadium 1%, Carbon 0.75%.

67) What are the causes of wear?

The tool is subjected to three important factors such as force, temperature and sliding action due to relative motion between tool and the work piece. So, the tool is wear easily.