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Ask the Expert Question-and-Answer Archive
(Hard Chrome Plating)

by Randy Taylor, Advanced Tooling Corporation.
August, 2010

Chrome Plating

Q. Which factors can cause a separation (missing of plated material) of a Chrome plated part as well as some chrome surface light cracks? Could it be related to the plating application procedure?

A. Factors? 1.) poor prep before plating 2.) out of spec bath chemistry 3.) poor anode design, condition or placement 4.) power supply out of spec 5.) poor DC connections 6.) poor pre-metal finish before plating 7.) operator error ......... just to name a few.

You will have to be more specific to get a more specific answer. Send a digital photograph of your problem and I might be able to give you a more concise answer.

Cracking of the plating deposit is a natural occurring phenomenon in hard chrome plating and not necessarily cause for concern, but we are talking very small micro cracking which should only be visible with the aid of magnification. Visual cracks in hard chrome are usually a sign of trouble. There are a number of causes, again if you can be more specific I'll try and give you a better answer.

Q2. Thanks for your prompt answer.

These are the pictures for the found condition, is it a normal surface cracking shown on the magnification photo?

This on a landing gear axle and as you might see it is a considerable detachment of chrome. There were no overheating signs or any other damage on the axle, just what it is on the pictures.

A2. Thank you for the photo. At first glance it doesn’t look like normal wear to me. It is most likely a failure of adhesion of the chromium coating to the base metal. To begin to sort out the how and why, I’d like to ask a couple more questions.

Can you provide me answers to the following?

1.) landing gear base metal (material & heat treat condition, if known, an example.. 4340M, HT 260 KPSI)
2.) type aircraft, i.e., Jet, helicopter, commercial, or other
3.) Photo is taken after “which step” in the repair process? Or is the photo of a part at disassembly?...I suspect at disassembly but I would like to be sure.
4.) Do you know the approximate age of the part?
5.) Assuming it’s a repair part, do you have access to any previous repair records?

I would enjoy helping you in this case, please get back to me as soon as you can with more answers and I’ll go from there…

Good Luck,

Randy Taylor

 



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