There are two main types of keys that key cutters are used for: parallel keys and woodruff 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 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:
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
.001 X 6 X 2400 = 14.4 IPM