High Velocity Cutters & Inserts Tech page
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Cutter diameter is based on using a square insert. Octagon styles produce a slightly smaller effective diameter but provide a 45° lead angle and 8 edges making it and the round style inserts the most popular. Using .032 radius square inserts are not intended for roughing steels and other hard and tough materials, but work well in aluminum and plastics.

To calculate RPM:
SFPM (from chart) x 3.82 divided by the cutter diameter equals RPM.

To calculate the feed rate:
Feed per tooth (FPT) x number of teeth(inserts) in cutter x RPM equals feed in inches per minute. Start in the middle of figures provided. Feeds and speeds assume an octagon insert (reduce feed by 20% for square insert to start), also assumes a rigid setup, part properly held, basic knowledge and experience of cutting, etc. Depth of cut will be appropriate to the horsepower available. Always start with a light depth of cut (.015-.025) if the horsepower is low or unknown, increasing as power is available. Always use proper safety gear and procedures.

General Application Tips

  1. Climb mill whenever possible.
  2. Width of cut (WOC) should be 60%-70% diameter of cutter when soft milling; WOC for hard milling should be about 30%.
  3. Always use the shortest reach toolholders possible for the application.
  4. Use light depth of cut and higher feeds and speeds when finishing.

Feed Rates