Machining Operation

1. Common Machining Operations
Kalpakjian

2. Kalpakjian
Parts of an “Engine” Lathe

3. www.blazingtech.net
www.bakerprovan.com.au
www.liberatorcrew.com
www.ticktockpro.com
Watchmaker’s lathe Typical “Engine” Lathe
Turret Lathe Big “Engine” Lathe

4. www.harrismachinetools.com
60 feet c-c
www.practicalmachinist.com
Really Big “Engine” Lathes

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

6. Machining
Parameters
DeGarmo

7. Kalpakjian
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. 1020 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.

8. Cutting
Forces
DeGarmo

9. Orthoganal
Model
(2-force)
DeGarmo

10. Orthoganal
Model
(2-force)
DeGarmo

11. Chip formation: chip types
Kalpakjian
DeGarmo

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

13. Kalpakjian
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

14. Heat rise in Cutting
Kalpakjian

15. Kalpakjian/Vieregge
Temperature of Cutting Tip

16. Kalpakjian / Chao & Trigger
Temperature of Cutting Tip

17. Kalpakjian
Max Temperatures of Cutting Materials

18. Kalpakjian/Sandvik
Machining Time of Cutting Materials

19. www.moldmakingtechnology.com
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)
Coated Carbide Cutting Inserts:
The norm for production machining
Kalpakjian/Kennametal
www.greenleafcorporation.com

20. Kalpakjian
Cutter Shape
and Geometry

21. Machining Costs
Kalpakjian

22. References
DeGarmo: E.P. DeGarmo et al, Materials and Processes in Manufacturing, Wiley, 2003.
Kalpakjian: http://www.nd.edu/~manufact/index3.htm