STAINLESS STEEL PARALLEL KEYS DIN 6885A

Parallel Keys DIN 6885A — Parallel Keys to DIN 6885A work on a completely different principle from every pin above: instead of fitting into a round hole, a parallel key sits in matching keyways machined into both a shaft and its mating hub, and transmits rotational torque between the two through shear across the key's flat faces, rather than through friction, an interference fit, or a taper. That makes it the standard solution wherever a shaft needs to drive a mounted component — a gear, pulley, coupling, or handwheel — while being prevented from spinning independently of it: the key transfers the drive load directly, and reliably, in a way that a shrink fit or a clamped collar relying on friction alone cannot guarantee under high torque. Sizing a parallel key is a matter of matching key width and height to the shaft diameter (standard tables link the two), then choosing a length that gives adequate shear area for the torque being transmitted without running so long that it no longer fits the available hub length — getting this wrong in either direction either under-engineers the joint or wastes material and machining time on an oversized keyway. It's worth being clear on what a parallel key doesn't do: it resists rotation between shaft and hub, but it does nothing to stop the hub sliding axially along the shaft, so a separate feature — a retaining ring, a shaft shoulder, or a set screw — is still needed wherever axial position also needs to be fixed. Grade selection follows standard fastener logic: A2 stainless is adequate for most general machinery and light drive applications, while A4 is worth specifying for keys exposed to washdown, marine, or outdoor environments, since a corroded key that swells slightly in its keyway can be difficult to remove during servicing, and pitting reduces the shear cross-section it depends on. Where axial retention is also needed alongside the key, a shaft collar or a circlip in a corresponding groove is the usual complementary fitting.

FAQs
Do parallel keys carry axial load?
No, a parallel key resists rotational torque only; axial position of the hub still needs a separate feature such as a retaining ring, shoulder, or set screw.

Is a parallel key sized from the shaft or the hub?
From the shaft diameter — standard tables give key width and height as a function of shaft size, and the keyway in the hub is then cut to match; a mismatch between the two is usually a hub machining error rather than a key sizing choice.

Can a worn keyway be repaired without replacing the shaft?
In some cases an oversized key can be fitted to a keyway that has worn slightly wide, but this is a compromise rather than a proper fix — significant wear generally calls for re-machining the keyway to the next standard size and fitting a correspondingly larger key rather than persisting with an undersized fit.