If you need to mate a part on a shaft, you need a key cutter. A key cutter, also known as a keyseat cutter, keyway cutter, or woodruff cutter, is a versatile tool that can be used to cut several different types of keyways. After cutting a keyway in a shaft, a key is placed in the seat and the two parts can now be mated together. This technique is used for parts like a gear, hub or pulley.

There are two main types of keys that key cutters are used for: parallel keys and woodruff keys.

Parallel Keys

The parallel keyway milling process starts by cutting a simple keyway slot, all the way through the axial diameter of the part. The keyseat is cut into the shaft and the key goes into the keyseat, between both parts forming a secure bond. You could use an endmill to make these cuts but using a key cutter is much easier. Key cutters come in a variety of cutter widths and cutting diameters. Pre-cut key stock is available in standard inch and metric sizes.

Woodruff Keys

Woodruff keys are an alternative to parallel keys. The keys are half-moon shaped and fit into a keyseat shaped as a matching semi-circle that is cut into the shaft. The part that is mated to the shaft has a rectangular slot cut.

Woodruff keys may be full radius or flat bottom but the keyseat will always be radiused by the Key Cutter.
Woodruff keys have several advantages over parallel keys:

  • They eliminate the milling near shaft shoulders which reduces stress concentrations and make it easier to maintain circularity constraints
  • They are better suited for high speed operation of the rotating shaft
  • The key has a more precise fit reducing play and improves the reliability of the key
  • A woodruff key may be easier to remove because of its circular profile of the seat. A parallel key requires removal along the axial distance of the seat.

RedLine Tools carries a full line of carbide key cutters for every application. We have solid carbide and carbide head with steel shank key cutters with teeth arrangements in standard, staggered, and fine. Head geometries include square, corner radius and full radius for seat cutting, deep slotting, soft material and push-pull applications. If you have a hard-to-reach application, we have both long shank and long reach cutters.

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Key Cutter Speeds and Feeds

  High Strength Tool Steel  A2, D2, P20, H11, H13, S2, D180-90
  Low Carbon  A36, 12L14, 12L15, 1005, 1018, 1020, 1108-1119, 1213-1215, 1513-1518, 4012, 5015, 9310
  Medium Carbon  1040-1095, 1140-1151, 1330-1345, 1520-1572, 4023-4063, 4120-4161, 4330-4340, 4620-4640,       8620-8660, 8740-8750, 6150, 51000, 52100
  M - Stainless Steels
  301-304L, 310, 316L, 321, 347  100
  Martensitic  403, 410,416, 420, 430, 431, 440  110
  Precipitation Hardening  12/8, 15/5, 17/4, AM-350/355/363, PH13-8M0, PH14-8/M0  120
  K - Cast Irons
  A536, J434, 60-40-18
  Gray  A48, A436, A319, Class 20, G4000
  Malleable  A220, A602, J158
  N - Non Ferrous
  Aluminium Alloys
  2014, 2024, 6061, 7075
  Aluminium High Silicon  A380, A390  300
  Brass/Bronze  Aluminium Bronze, Low Silicon Bronze  230-250
  Composities  G-10, Firerglass, Graphite, Graphite Epoxy, Plastics  180-200
  S - High Temp Alloys
  Cobalt Base
  Stellite, HS-21, Haynes 25/188, X40, L605  80
  Iron Base  Incoloy 800-802, Multmet N-155, Timkin 16-25-6, Carpenter 22-b3  80
  Nickel Base  Inconel 625/718, Inco 700, 713C, 718, Monel 400-401, 404, K401, Rene, Rene 41 & 95, Hastelloy, Waspoloy, Udimet 500 & 700  80
  Titanium  Commercially Pure, 6AI-4V, ASTM 1/2/3, 6AI-25N-4Zr-2Mo, Ti-8AI-4Mo  90

Speeds Formula for Calculating RPM

SFM(4) = F

F / Diameter = RPM

EXAMPLE: 1/2" Cutter Diameter in Aluminum

SFM(300) X 4 = 1200(F)

1200(F) / .500 = 2400 RPM

Feeds Formula for Calculating IPM

.001 (# of Teeth in Cutter) RPM = IPM

EXAMPLE: 1/2" Cutter Diameter in Aluminum

.001 X 6 X 2400 = 14.4 IPM