2. Tool Geometry for engineering studrnts.pdf

tool design

1. Introduction
Tool Geometry

2. Concept of Rake and Clearance Angles
Tool Geometry

Fig. Probable forms of early
cutting implements
(a)
(b)

3. Concept of Rake and Clearance Angles
Tool Geometry

Fig. Concept of Rake and Clearance Angles

4. Concept of Rake and Clearance Angles
Tool Geometry

Fig. Concept of Rake and Clearance Angles

5. Types of Rake Angles
Tool Geometry

a
b
c
Fig.: a. Positive Rake
b. Negative Rake
c. Zero Rake

6. The use of positive rake
angles is recommended:

When machining low strength ferrous
and non-ferrous materials and work
hardening materials.
When using low power machines.
When machining long shafts of small
diameters.
When the setup lacks strength and
rigidity.
When cutting at low speeds.
Positive Rake Angle
Tool Geometry

7. Negative Rake Angle
The use of negative rake
angles is recommended:

When machining high strength alloys.

When there are heavy impact loads
such as in interrupted machining.

For rigid setups and when cutting at
high speeds.
Tool Geometry

8. Basic Features of a Single Point Tool
Principal Cutting Edge
Auxiliary Cutting Edge
Principal Flank Surface
Auxiliary Flank Surface
Rake Face
Tool Nose
Base
Single Point
(rake face, principal cutting edge, auxiliary cutting edge, principal flank
surface, auxiliary flank surface and tool nose)
Shank
Tool Geometry

9. Left Hand & Right Hand Tools
Tool Geometry

10. Systems of Tool Geometry
Tool in Hand System: salient features of
the cutting tool point are identified or
visualized

Machine Reference System - ASA
System

Tool Reference System
Orthogonal Rake System - ORS
Normal Rakes System – NRS

Work Reference System - WRS
Tool
Geometry

11. ASA – Planes of Reference
Fig.: Planes and Axes of Reference in ASA System
Tool Geometry

12. ASA – Planes & Axes of Reference
Fig.: Planes and Axes of Reference in ASA System
Tool Geometry

13. P

14. 14

15. 15

16. Tool Angles in ASA System
Fig.: Tool Angles in ASA System
Tool Geometry

17. Tool Angles in ASA System
Tool Geometry

18. Tool Angles in ASA System
Tool Geometry

19. Tool Angles in ASA System
Tool Geometry

20. ASA – Tool Signature
Tool Geometry

21. ORS – Planes of Reference
Fig.: Planes and Axes of Reference in ORS System
Tool Geometry

22. ORS – Planes & Axes of Reference
Fig.: Planes and Axes of Reference in ORS System
Tool Geometry

23. Tool Angles in ORS System
Fig.: Tool angles in ORS System
Tool Geometry

24. Tool Angles in ORS System
Tool Geometry

25. Tool Angles in ORS System
Tool Geometry

26. Tool Angles in ORS System
Tool Geometry

27. ORS – Tool Signature
Tool Geometry

28. Tool Angles – Sign Convention
+
_
Fig.: Sign Convention for Inclination Angle
Tool Geometry

29. Conversion of Rake Angles
A
E
C
D
B
F
Conversion of Tool
Geometry

Rake Plane
Base Plane

30. ASA to ORS - Conversion
for T = unity
A C
F
D
E
T
A
B
E
A
T B
F
T
A
B
D
T
C B
A
, B
Conversion of Rake Angles

31. ASA to ORS - Conversion
Since triangles
OCE and BCD are similar:
A, B C
F
D
O
E
Conversion of Rake Angles

32. ASA to ORS - Conversion
unity
Conversion of Rake Angles

33. ASA to ORS - Conversion
Similarly by considering
similar triangles BDC and GFC:
A, B C
F
G
D
O
Conversion of Rake Angles

34. ASA to ORS - Conversion
unity
Conversion of Rake Angles

35. ASA to ORS - Conversion
Transformation
Matrix
Both the above equations can be written
in matrix form :
Conversion of Rake Angles

36. ORS to ASA - Conversion
It has been already proven that:
From the above, it can be written as:
Conversion of Rake Angles

37. ORS to ASA - Conversion
= ?
Conversion of Rake Angles

38. ORS to ASA - Conversion
=
Conversion of Rake Angles

39. ORS to ASA - Conversion
Transformation
Matrix Conversion of Rake Angles

40. Principal Flank Angles
Principal Flank Surface
B O
C
D
P
A
λ
Conversion of Clearance Angles

41. Principal Flank Angles
Classification

P , O
D
C
B
A
O P
B
O
P
A
O
P
D
O
P C
Principal Flank
Auxiliary Flank

42. ASA to ORS - Conversion
Since triangles
AED and BOD are similar:
P, O D
C
B
E
A
Conversion of Clearance Angles

43. ASA to ORS - Conversion
unity
Conversion of Clearance Angles

44. ASA to ORS - Conversion
Similarly by considering
similar triangles OBD and FCD :
P, O D
C
F
B
E
Conversion of Clearance Angles

45. ASA to ORS - Conversion
unity
Conversion of Clearance Angles

46. ASA to ORS - Conversion
Both the above equations can be written
in matrix form :
Conversion of Clearance Angles

Transformation
Matrix

47. ORS to ASA - Conversion
It has been already proven that:
From the above, it can be written as:
Conversion of Clearance Angles

48. ORS to ASA - Conversion
= ?
Conversion of Clearance Angles

49. ORS to ASA - Conversion
=
Conversion of Clearance Angles

50. ORS to ASA - Conversion
Transformation
Matrix
Conversion of Clearance Angles

51. ASA&ORS - Designation
Tool geometry

52. NRS system- Planes of Reference
Tool geometry

Normal Rake System (NRS) utilizes three
reference planes in order to measure various
tool angles.

Reference Plane (π
R): It is a plane
perpendicular to the cutting velocity vector
(V
c).

Cutting Plane (π
C): It is a plane
perpendicular to reference plane (π
R) and
contains the principal cutting edge of the tool.

Normal Plane (π
N): It is a plane
perpendicular to the principal cutting edge of
the tool. Normal plane may not be
perpendicular to the reference plane (π
R) and
Cutting Plane (π
C). However, normal plane is
always perpendicular to the principal cutting
edge.

53. Tool angles in NRS system
Tool Geometry

Normal Rake Angle (γ
N):
It is the angle of orientation of tool’s rake
surface from the reference plane (π
R) and
measured on normal plane (π
N).


Normal Clearance Angle (α
N):
It is the angle of orientation of tool’s
principal flank surface from the cutting
plane (π
C) and measured on normal plane
(π
N).

Auxiliary Normal Clearance Angle (α
N’):
It is the angle of orientation of tool’s
auxiliary flank surface from the auxiliary
cutting plane (π
C’) and measured on
auxiliary normal plane (π
N’).

54. Tool Designation in NRS system
Tool Geometry

Maximum Rake System (MRS):
it consists of one rake angle, known as maximum rake angle; one
clearance angle, known as minimum clearance angle.

55. ORS TO NRS SYSTEM
Tool representation in NRS system

56. Sectional view in NRS system
ORS TO NRS SYSTEM

57. Relation between rake angles
ORS TO NRS SYSTEM

58. ∠AOB = γ
o
∠AOC = γ
n
∠BAC = λ
Now,
AC = ABcosλ
OAtanγ
n= (OAtanγ
o)cosλ
Hence, tanγ
n= tanγ
ocosλ
ORS TO NRS SYSTEM

59. Relation between clearance angles
ORS TO NRS SYSTEM

60. AC = ABcosλ
AA’cotα
n= AA’cotα
ocosλ
Hence, cotα
n= cotα
ocosλ

Similarly it can be proved,
cotα
n’= cotα
o’cosλ’
∠ABA’ = α
o
∠ACA’ = α
n
∠BAC = λ
ORS TO NRS SYSTEM

61. Master line
Tool Geometry

Master line is the line of intersection
between the Reference Plane (π
R) and any
one of the three tool point surfaces.
Master Line for Rake Surface:
It is the line of intersection between the
Reference Plane (π
R) and Rake surface of
the cutting tool.

Master Line for Principal Flank Surface:
It is the line of intersection between the
Reference Plane (π
R) and Principal Flank
surface of the cutting tool.

Master Line for Auxiliary Flank Surface:
It is the line of intersection between the
Reference Plane (π
R) and Auxiliary flank
surface of the cutting tool.

62. in triangle BDC
A, B C
F
D
O
E
Conversion of Rake Angles

M
Maximum Rake Angle (ASA)

63. similarly
in triangle BFE
A, B C
F
D
O
E
Conversion of Rake Angles

M
Maximum Rake Angle (ORS)

64. P, O D
C
B
E
A
Conversion of Clearance Angles

in triangle OBD
Minimum Clearance Angle (ASA)
M

65. P, O D
C
B
E
A
Conversion of Clearance Angles

Similarly
in triangle OCA
Minimum Clearance Angle (ORS)
M

66. References
•Metal Cutting Principles, M.C. Shaw, Oxford
University Press

•Machining & Machine Tools,
AB Chattopadhyay, Wiley

•Principles of Metal Cutting, GC Sen and A
Bhattacharya, New Central Book Agency

•Principles of Metal Cutting, G Kuppuswamy,
Universities Press