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Coating Considerations: When and Where to Use Electroless Nickel Plating

Deciding if it makes sense to apply a protective coating such as nickel to your linear motion components depends on several factors. Perhaps most important is the work environment your motion assembly will operate in—and whether or not your assembly must stand up to significant corrosion or wear factors. For high-performance motion control applications such as those found in the aerospace, semiconductor, medical, pharmaceutical, and food and beverage industries, investing in electroless nickel (EN) plating on your precision bearing assemblies will help extend component lifetimes.

At Rollon, we offer customized, application-specific coating formulations that can be added to our linear guide rails, raceways, and precision bearing surfaces prior to shipment to provide additional insurance against corrosion and wear. Various alloying elements such as cobalt and boron are added to the nickel-base formula to achieve different properties, ranging from extreme corrosion resistance at one end of the spectrum to extreme hardness at the other.

With regard to corrosion protection, the Ni-base coatings we apply to our linear motion components achieve 1000 hours or better of salt spray resistance as tested to ASTM B117 standards. For wear, Rockwell hardness values of C58 to C70 are achievable with coating thicknesses from 2.5 to 10 microns. And if lubricity is needed in a clean room environment, nickel-Teflon formulas are available to provide grease-free lubrication on all rolling or sliding surfaces. In addition, the Ni-base coatings we offer are FDA-approved and food grade compliant for use in food and beverage applications.

Another factor to keep in mind when considering special coatings for linear motion components is uniformity. The EN process applies nickel plating in a nearly perfect manner, achieving uniform thickness within millionths of an inch. This is not possible with electrolytic processes that tend to build up plating at the corners of surfaces, resulting in a “dog bone” effect that can be detrimental to achieving smooth, high-speed motion. Another benefit of the EN process versus electrolytic plating is the ability to coat all surfaces of the complete motion assembly—including counter-bored bolt holes that can rapidly corrode if not coated.

For your next application requiring precise motion and extreme durability, consider adding an EN coating to your bearing surfaces and linear motion components. Rollon engineers can help you select the exact EN formula to meet very specific requirements for corrosion and wear resistance. Keep in mind that nickel plating can be applied to a variety of metal surfaces, including bearing steel and aluminum, achieving 1.3 to 3´ the corrosion resistance of 440C stainless steel.