Metal finishing Q&As since 1989

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Duplex Nickel plus hard chrome plating thickness vs Duplex Nickel decorative chrome thickness

2007

We are providing duplex nickel thickness of 8 microns & hard chrome thickness of 8 microns over steel tube (PART A ) to get specified CASS test of 48 hours. The tube is ground to high surface finish before plating.

For another part, ( B) we do plating of duplex nickel of 20 microns plus bright chrome of flash, i.e., 0.3 microns to get CASS life of 24 hours. The tube here is buffed before plating.The thickness is based on IS / JIS std.

Both parts are exposed to exactly similar environment on the motorcycle.

To save cost without compromising quality (life), can we reduce the thickness of PART B ? What should be the thickness ? If not why not? What is the technical justification for the above differences ?

S.W.DESHPANDE
Auto component manufacturing - NASHIK

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Neither chrome thickness is thick enough to provide much corrosion protection. The chrome on A will offer a more scratch resistant surface than B will, but I would bet that the higher duplex nickel on B will give a longer CASS test than A will.
If you have no spec to comply with, B should work just fine if you do not need scratch resistance.

James Watts
- Navarre, Florida
2007

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Discuss this with the motorcycle manufacturer. There may be a difference in function.

Ken Vlach [deceased]
- Goleta, California
Finishing.com honored Ken for his countless carefully researched responses. He passed away May 14, 2015.
Rest in peace, Ken. Thank you for your hard work which the finishing world, and we at finishing.com, continue to benefit from.
2007

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Hi DESHPANDE. 20 microns of duplex nickel is by no means excessive for exterior automotive applications. If your customer prides himself on selling cheap motorcycles, it may be possible to get away with slightly less nickel thickness, but you wouldn't go with less than 20 microns on a Harley.

Real world performance is what dictates required plating thickness. CASS tests are a quality assurance tool to quickly determine when a process has gone south -- they are not something anyone should be designing to, and you would never reduce a plating thickness because you passed a CASS test with a margin of comfort.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
October 2013