Single point cutting tool

1. Single Point Cutting Tool Geometry
1
Prof. S. S. Pande
Mechanical Engineering Department
Indian Institute of Technology, Bombay

2. Outline
• Tool Geometry, Tool Angles
• Systems for Tool nomenclature
- ISO System - ORS/NRS
- American Standards System - ASA
• Tool Angle Conversion: ISO ASA
- Mathematical Basis

3. Basic Tool Shape
2β
Work
Tool
P
Wedge angle : 2β

4. Cutting Efficiency
2β
Tool
P
R
R
Cutting Efficiency =
P = 2R sinβ

5. Orthogonal Cutting Geometry

6. Orthogonal Cutting
Velocity V

7. Orthogonal Cutting
Characteristics
• Cutting edge Perpendicular to
cutting Velocity Vector
• Plain Strain (2D) phenomenon
• No Spread of material across

8. Oblique Cutting
Tool
Chip
λ
Work piece
V

9. Oblique Cutting
Characteristics
• Cutting edge at an angle(λ) to normal to
velocity vector in the cutting plane
• Inclination angle λ
- modifies Tool angles
- governs Direction of chip flow
Stabler’s Law for Chip flow
nc = k. λ nc = chip flow angle
K = 0.8 – 1.0

10. Free and Restricted Cutting
Feed
Motion
Tool

11. Chip Flow
Free Restricted

12. Single Point Tool Geometry

13. Tool Nomenclature Systems
Tool in Hand
• ISO System : ORS/ NRS
- Orthogonal/ Normal Reference System
• American Standards Association (ASA)
system
Tool in Machine
• Tool /Insert setting in fixture

14. Tool Angle Reference Systems
ORS and ASA
λ
γx
γy
γo

15. Tool Reference Planes
Feed
πB
πo
πc
Cutting Orthogonal
Basic
axis
v

16. Orthogonal (ORS) Reference Planes
Trace
of πo
Trace
of πc
πB
πB
πc
πo

17. Reference Planes - ORS
View in πo
View in πc
πc
πB
πo

18. Reference Planes – ASA system
Y
X
X
V
πx
πy
πB

19. ASA Reference Planes
X X
Y
πy
πx
Y

20. Tool Angles – ASA System
Y
X
V View in πx Plane
View in πy Plane

21. Ø = Plan Approach angle
Øs = Side cutting Edge angle
Øe = End cutting Edge angle
Ø = 90 - Øs
Tool Angles
Feed
Ø
Øs
Øe
X X

22. Tool Designation
ASA System
γy , γx , αy , αx , Øe , Øs , r
γy : Back rake angle
γx : Side rake angle
αy : Front clearance angle
αx : Side clearance angle
Øe : End cutting Edge angle
Øs : Side cutting Edge angle
r : Nose radius (mm)

23. Tool Angle Conversion
ORS ASA
(γo, λ) (γx , γy )
Ø = Plan Approach angle

24. Tool Angle Conversion
ASA ORS
(γx , γy ) (γo, λ)
Ø = Plan Approach angle

25. Does Orthogonal Plane πo
represent True rake angle?

26. Orthogonal and Normal Reference Planes
λ
πo
πc
πn

27. Tool Angle Conversion
ORS NRS
γo γn

28. Tool in Machine System
Static angles on Tool/Insert change
due to
• Setting in tool Holders/ Fixtures
• Tool/ Work relative motion.

29. Inserts in Tool Holder

30. Inserts and Tool Angles

31. Tool Setup on Machine