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Maximum possible chrome plate thickness

I am trying to repair a Rotor made out of Stainless Steel 15-5PH and and average hardness of 35.5 HRC. We want to restore dimensions by chrome plating per FED QQ-C-320 class 2, but I have not been able to find out what is the maximum thickness that I can plate on the surface to grind and then polish to it original dimensions. QQ-C-320 gives a minimum but not a maximum, what is the maximum? or where can I find that information?

Rodrigo Gonzalez
Repair and Overhaul Aircraft Parts - Hialeah, Florida, USA
2004

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First of two simultaneous responses -- 2004

Considering your location, you probably are working on a PWA part and they certainly have a maximum. But, they do allow a sulfamate nickel build, machine and a chrome cap. Whoever the OEM is will have a definite specification, at least the 4 companies parts that I worked on. For reference, PWA used to be a max application of 15 thou per side ground back to a max of 10 thou per side. It is a highly stressed plate and you run into cracking and delamination problems at the high build. 3 thou was the minimum to maintain the integrity of the part as it seldom was identically center in the pre machine and the final grind operations. Rotating parts are held to a higher level of QC than non rotating parts as there is a lot more grief if they fail.

You are under 40 RC, so are you prebaking or shot peening?

Are your chrome grinders good, or do you have a lot of failures that get blamed on the platers?

James Watts
- Navarre, Florida

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Second of two simultaneous responses --

Theoretically there is no maximum thickness. Thicknesses up to .030" or .040" are common.

Jeffrey Holmes, CEF
Spartanburg, South Carolina
2004

We are doing chrome plating of cylinder liner used in locomotives.What is the allowable maximum coating thickness in chrome plating?

DEVARSHI GAUR
works manager - Patiala, Punjab, India
December 28, 2009

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Hi, Devarshi. Your question was already answered directly above, so I don't understand quite what you are asking. Can you rephrase your question in terms of what has already been said so that we understand your difficulty? Thanks.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
December , 2009