Electroless Nickel Coating For Crankshaft Bearings

Electroless nickel plating and a nitride under-coat can have big advantages over hard chrome plating. Not just for their combined ability to cover complex surfaces uniformly. But for their properties derived beyond the as-deposited state. Various heat treat after plating can give rise to harder or more ductile, stable, adherent structures of electroless nickel.

And that is especially important for the more demanding applications where abrasion, high stress and Crankshaft Grinding fatigue are factors. For example, the lubricating regime of crankshaft bearings. Friction is critical, but so is power and strength. What is the right combination? That is the question designers want to know.

Today, most design purposefully under size the crankshaft diameter to lower friction.

But studies have shown undersized diameters require greater oil film compensation. And that means subsequent loss in power and strength.

So, what if the exposed bearing surfaces actually lubricated, intrinsically? Would greater films of oil still be needed? And what if those nickel surfaces were wettable, allowed the film to spread.

We suspect wear would not be as big a concern. So power and strength could be maximized. Crankshaft diameter reduction could be held to a minimum.

Of course loads on crankshaft bearings vary. And they can be high. That is why nitride pre-treatments can be ideal for extending fatigue and wear life. We believe, though, electroless nickel coatings can play an important role for the rubbing surfaces in contact. Energy loss can be held to a minimum in the absence of a sufficient fluid film.

In addition to the mechanical aspects of the electroless nickel plating, be sure to consider corrosion protection, too. That will be both a function of the heat treat carried out and thickness of the plating.

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William Gunnar, a degreed scientist, researcher, engineer, and friend, has helped thousands of ‘best of class’ product designers and equipment manufacturers — for nearly 20 years now — surface engineer with coatings for success.

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