TPM ENGINEERING SNAPSHOT · Nº 01

MILLING vs TURNING

Two ways to make chips. What each one is for — and what we run it on.

True Precision Machining
WORKPIECE ROTATESSINGLE-POINT TOOL FEEDS

TURNING

LATHE — THE PART SPINS

  • Cylindrical geometry: shafts, bushings, fittings, threads
  • Bar-fed production runs lights-out — lowest per-part cost
  • On our floor: Mori Seiki NL2500SY · Doosan Puma turn-mills · bar to Ø3.0″
  • Live tooling adds milled flats & cross-holes in the same setup
BEST TOL.
0.0002″
FINISH
16–63 µin Ra
CUTTER ROTATESWORKPIECE FEEDS

MILLING

MACHINING CENTER — THE TOOL SPINS

  • Prismatic & 3D geometry: housings, brackets, contoured surfaces
  • Multi-point cutter — flats, slots, pockets, true 3D
  • On our floor: Haas VF-6 (64″×32″×30″) · Kitamura Mytrunnion 4G 5-axis
  • 5-axis holds the part once — kills tolerance stack-up between setups
BEST TOL.
0.0002″
FINISH
16–32 µin Ra
The math
we run
RPM = 12·SFM / (π·D)
both processes — surface speed sets spindle speed
IPM = RPM·n·IPT
milling feed — n flutes × chip load
feed = IPR
turning feed — inches per revolution
Feature Turning Milling
Main motion Workpiece rotates Cutter rotates
Cutting tool Single-point Multi-point (flutes)
Natural shapes Cylindrical — Ø features Prismatic & contoured
TPM machines Mori Seiki · Doosan Puma · Tsugami Swiss Haas VF-6 · Makino · Kitamura 5-axis
Best tolerance 0.0002″ (0.0001″ Swiss) 0.0002″ (5-axis)

Rule of thumb: if the critical feature is a diameter, turn it. If it's a face, pocket, or contour, mill it. Round part with milled features? Our turn-mills do both in one setup.