common machining operations kalpakjian. parts of an “engine” lathe
TRANSCRIPT
Common Machining Operations
Kalpakjian
Kalpakjian
Parts of an “Engine” Lathe
www.blazingtech.net
www.bakerprovan.com.auwww.liberatorcrew.com
www.ticktockpro.com
Watchmaker’s lathe Typical “Engine” Lathe
Turret Lathe Big “Engine” Lathe
www.harrismachinetools.com
60 feet c-c
www.practicalmachinist.com
Really Big “Engine” Lathes
CNC Lathe: aka “Turning Center”
(carriage is mounted toward back, “upside down”)
www.machineryvalues.com
MachiningParameters
DeGarmo
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.
CuttingForces
DeGarmo
OrthoganalModel(2-force)
DeGarmo
OrthoganalModel(2-force)
DeGarmo
Chip formation: chip types
Kalpakjian
DeGarmo
Merchant’s Model(Simplified 2-force)
DeGarmo
Kalpakjian
Chatter
Vibrational resonance of entire machining system, especially workpiece-cutter.Causes poor surface finish, fast tool wear, noiseFactors: stiffnesses of workpiece, cutter, machine cutting params: speed, feed, DOC cutter geometry: rake, clearancesSolutions: Change the cutting params esp. speed Increase stiffnesses
Heat rise in Cutting
Kalpakjian
Kalpakjian/Vieregge
Temperature of Cutting Tip
Kalpakjian / Chao & Trigger
Temperature of Cutting Tip
Kalpakjian
Max Temperatures of Cutting Materials
Kalpakjian/Sandvik
Machining Time of Cutting Materials
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
Kalpakjian
Cutter Shape and Geometry
Machining Costs
Kalpakjian
References
DeGarmo: E.P. DeGarmo et al, Materials and Processes in Manufacturing, Wiley, 2003.
Kalpakjian: http://www.nd.edu/~manufact/index3.htm