Wednesday, September 23, 2009

Resisting fretting rust

No need to fret!
Shaft coating allows quick gearbox removal


Nord Drivesystems has developed a specialised surface treatment option for hollow drive shafts that resists the formation of fretting rust or friction corrosion - reducing wear and facilitating the easy removal of gear motors for gearbox and motor servicing or replacement.

Fretting rust or friction corrosion occurs in fixed mechanical joints under load and vibration where at least one surface material contains iron. Whilst it is commonly associated with bolted tension members in structures like bridges, the phenomenon is also seen in splines and drive shafts (even stainless steel versions), where the clamped drive and driven shaft surfaces actually experience microscopic levels of relative motion and slippage.

The oxidised debris is an abrasive material that contributes to increased wear and, much more of a problem for drive shafts, the miniscule fragments become compressed between the surfaces often making removal extremely difficult - sometimes resulting in costly shaft damage.

Nord’s RS coating option, available across its wide range of gearmotors, produces an extremely hard wearing and corrosion resistant layer of approximately 10 microns thickness that reduces surface friction characteristics of the hollow shaft and significantly reduces the formation of fretting rust. The treatment allows effortless gearmotor shaft removal and eliminates the potential for destruction of the insert shaft, saving costs by minimising maintenance and repair timescales.

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