1. Common Machining Operations
Kalpakjian

2. Parts of an “Engine” Lathe
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3. Typical “Engine” Lathe
Watchmaker’s lathe
Typical “Engine” Lathe
Turret Lathe
Big “Engine” Lathe

4. Really Big “Engine” Lathes
60 feet c-c

5. CNC Lathe: aka “Turning Center”
(carriage is mounted toward back, “upside down”)

6. Machining
Parameters
DeGarmo

7. Machining: Turning Depth of Cut = DOC = (Dbefore – Dafter) / 2
Cutting Speed = Speed of metal moving towards cutting tip
Usually called “Surface Feet per Minute”, SFPM, SFM
Each cutting tool & workpiece material combo has a max SFM for decent tool wear.
HSS & alum: 800 SFM
HSS & 1020 steel: 110 SFM
HSS & 1090 steel: 80 SFM
HSS & hard 4140: 30 SFM
TC & 1020 steel: 1000 SFM
SFM = r*w
= D * RPM * (π/12)
≈ D * RPM / 4
RPMmax = 4 * SFM / D
(most useful machining formula)
E.g., find RPM for turning
2” dia steel:
RPM ≈ 4*110/2 = 220
RPM may need to be less due to chatter!
Most relations are similar
for milling, but D=cutter dia.
Kalpakjian

8. Cutting
Forces
DeGarmo

9. Orthoganal
Model
(2-force)
DeGarmo

10. Orthoganal
Model
(2-force)
DeGarmo

11. Chip formation: chip types
DeGarmo
Kalpakjian

12. Merchant’s Model
(Simplified 2-force)
DeGarmo

13. Chatter
Vibrational resonance of entire machining system, especially workpiece-cutter.
Causes poor surface finish, fast tool wear, noise
Factors: stiffnesses of workpiece, cutter, machine
cutting params: speed, feed, DOC
cutter geometry: rake, clearances
Solutions:
Change the cutting params
esp. speed
Increase stiffnesses
Kalpakjian

14. Heat rise in Cutting
Kalpakjian

15. Temperature of Cutting Tip
Kalpakjian/Vieregge

16. Temperature of Cutting Tip
Kalpakjian / Chao & Trigger

17. Max Temperatures of Cutting Materials
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18. Machining Time of Cutting Materials
Kalpakjian/Sandvik

19. Coated Carbide Cutting Inserts: The norm for production machining
Layers are 2-10 microns thick:
TiN: titanium nitride (low friction, gold appearance)
TiCN: titanium carbonitride (wear resistance)
Al2O3: Alumina (chemical stability, wear resistance)
Tungsten Carbide substrate (~shock and wear resistance)
Kalpakjian/Kennametal

20. Cutter Shape
and Geometry
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21. Machining Costs
Kalpakjian

22. References
DeGarmo: E.P. DeGarmo et al, Materials and Processes in Manufacturing, Wiley, 2003.
Kalpakjian: