Indexable Milling Cutter Body Reference — Which Insert Fits?

Decode a cutter body designation such as BAP400R-50-22-4T or KM12-50-22-4T: what each part of the code means, what diameter and arbor bore it takes, and which insert class drops into the pocket.

1  Read your body codeType it as stamped, e.g. BAP400R-50-22-4T or BAP300R.
2  Get the insert class11 mm, 16 mm or 1204 square.
3  Match screw & wrenchCross-checked against our screw reference page.

How the code is built

A designation such as BAP400R-50-22-4T is read left to right. The series block decides the insert; the numbers after it describe the body.

Part of codeMeaningExample
BAP90 degree right-angle shoulder and face millBAP400R
300R / 400RInsert series. 300R = APMT 11 series, 400R = APMT 16 series400R
50Cutter head diameter in mm50 mm
22Arbor bore diameter in mm22 mm
4TNumber of flutes (teeth)4 flutes

The 400R block decoding as the APMT 16 series is taken from the cutter manufacturer designation breakdown. Body material is typically hardened forged alloy steel; insert screws are grade 12.9.

Full body reference table — every series covered (no search needed)
Body seriesExample designationsCutter typeInsert classScrewTorx wrenchArbor / mount

Screw and wrench sizes are carried over from our insert screw and Torx wrench reference, where the mounting-hole diameters are listed.

Three things the code does not tell you

Before you order inserts — 5-point self check

  1. Write the full body designation off the body itself, not off an invoice or a website title.
  2. Read the series block. 300R points to the 11 mm class, 400R to the 16 mm class.
  3. Confirm the cutter type. Shoulder (90 degree) and face mill (45 degree) bodies in the same family take different inserts.
  4. Match the insert class to the screw. 11 mm class uses M2.5 and T8; 16 mm class uses M4 and T15. If your old screw does not match, the class is wrong.
  5. Measure the arbor bore before buying the arbor. 22 mm and 25.4 mm bodies are both sold under the same series name.