Erie Industrial Supply Company
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End Mill Selections

Flute selection with end-mills offers the same challenges as with drills and taps. Flute selection is normally a matter of compromise between available chip space and strength of the remaining core of the tool. Obviously, deeper and wider flutes make a smaller diameter core cross-section, which becomes sometimes unacceptably weaker. Providing a stronger, thicker core reduces space available in the flutes for chips. Considerations include:

  • Softer materials can be done with deep wide flutes/thinner cores.
  • Harder materials require a thicker core but benefit from more flutes.
  • Three flutes can have almost as much chip space as 2 flutes, but stronger cores.
  • Aggressive helix angles can eject chips rapidly, reducing the need for wide, deep flutes.
  • More flutes/lands yield better finishes.

With increasing the number of flutes, you do have the opportunity to increase production. (IPM)

The calculation for this is: RPM X IPT (feed per tooth) x # Flutes (cutting teeth) = IPM

Milling stainless steel 50 SFM at 381 RPM’S at .002 IPT
2 Fluted mill: 381 RPM’S x .002 IPT x 2 Flutes = 1.524 IPM
3 Fluted mill: 381 RPM’S x .002 IPT x 3 Flutes = 2.286 IPM
= 3.048 IPM