What Are Machine Keys,
Also Known as Shaft Keys?
Machine keys are used in power transmission to transmit torque between a shaft and a shaft mounted component such as a gear, pulley, or coupling. Both the shaft and the component must be machined with a keyway of the appropriate size and style for the key to be used.
Machine keys are sometimes called shaft keys, or sunk keys, and are available in a variety of types and include Parallel Keys, Flat Keys, Woodruff Keys, Square Keys, Rectangular Keys, Plain Taper Keys, Gib-Head Taper Keys, Perpendicular Pins and the Feather Key.
Machine Keys have a wide range of applications in our daily lives. Machine Keys hold machinery parts in place or align components. Machine Keys are used in power transmissions, motors, speed reducers, variators, automobiles, motorcycles, and industrial machines.
Each machine key has few attributes such as width, height, length, finish, and tolerance. It is important to understand the tolerance attribute. There are two type of tolerance. An oversize tolerance machine key provides a slightly tighter fit and an undersize tolerance machine key provides a slightly looser fit. Tolerance is specified in standards such as DIN6885 and JIS B 1301. Machine keys with metric (mm) measurement are almost always made as close tolerance undersized, whereas machine keys with imperial measurement (inch) tend to be made in both oversize and undersize tolerance sizes.
