Drives and Controls Magazine

Shaft coating allows quick gearbox removal

22 September, 2009

Nord Drivesystems has developed a surface treatment for hollow drive shafts that resists the formation of fretting rust or friction corrosion, thus reducing wear and making it easier to remove gear motors for servicing and replacement.

Fretting rust or friction corrosion occurs in mechanical joints under load and vibration where at least one of the surface materials contains iron. It is commonly associated with structures such as bridges, but the phenomenon also occurs in splines and drive shafts (even stainless-steel versions), where the clamped drive and driven shaft surfaces experience microscopic levels of relative motion and slippage.

The oxidised debris is abrasive and contributes to increased wear. With drive shafts, the tiny fragments can become compressed between the surfaces making removal extremely difficult. This can sometimes lead to costly shaft damage.

Nord`s RS coating, available as an option for its gearmotors, produces a hard-wearing, corrosion-resistant layer about 10 microns thick that reduces surface friction in the hollow shafts and reduces the formation of fretting rust. The treatment makes it easy to remove gearmotor shafts and eliminates the risk of destroying the insert shafts, thus reducing the need for maintenance and repairs.