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Replating chrome onto existing chrome

adv.
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Quickstart:
     There are two general types/applications of chrome plating:
       • Decorative chrome, which is actually a very thin plating of chrome over a relatively thick layer of nickel plating, and
       • Hard chrome, which is very heavy chrome plating for wear resistance and oil retention.
     Please see our Intro to Chrome Plating if interested.
     While decorative chrome would almost always be stripped and redone, it is common to try to save the old hard chrome when replating.

Q. we need to do replating of hard chrome on chrome plated components (rods) which are already post polished and ground.

⇩ Related postings, oldest first ⇩

Q. I was after some feedback on how to plate hard chrome plating over existing chrome in a HEEF 25 type solution. We have tried a few different ways and none seem to be giving us consistent enough results to keep persisting with them. The plate seems to cover about 90% of the job beautifully but a few small areas blister or flake. We know of other people who consistently obtain perfect results. Our suppliers seem to know very little about the product in terms of procedures that need to be followed to obtain good results.

I would greatly appreciate any suggestion.

Regards,

RECOMMENDED CHROME PLATING BOOKS for Shops, Specifiers, & Engineers "Chromium Plating" by Weiner & Walmsley (1980) avail from eBay, AbeBooks, or Amazon "Hard Chromium Plating" by Robert K. Guffie (1986) avail from AbeBooks, or Amazon "Electrodeposition of Chromium from Chromic Acid Solutions" by George Dubpernell (1977) avail from eBay, AbeBooks, or Amazon "Hard chromium plating: A Handbook of Modern Practice" by John David Greenwood (1971) avail from eBay "Chrome Plating Simplified" by Clarence H. Peger (1977, looseleaf) very rarely avail from Amazon but copies are available in a few libraries) "A Chromium Plating Bath With The Fluoride Ion" by Alfred Perlenfein (2013) avail from eBay, AbeBooks (as an Amazon Associate & eBay Partner, we earn from qualifying purchases) A. Mr. Adams, One of my clients is plating hard chrome over hard chrome in HEEF 25 type of process whenever he doesn't get required thickness in an automated line. If you are not stripping chrome Please follow the steps below. 1. Give good pretreatment prior treatment. 2. Pass low current for about 15 minutes i.e around 25 % of the total current you generally pass. 3. After the above step plate the substrate to the required thickness, but pass around 20 % less current density than your regular current density and give more time. The above steps should help you in getting good plating as my client is already getting. N.K.Praveen Kumar - Secunderabad, India A. You probably need to go to tech services at the manufacturer for the best information. You need to be careful with the caustic clean and the acid etch as it is easy to mess up the surface. We used to use a short reverse in the plating tank followed by a voltage ramp up to the final voltage/amperage. If the part has any considerable size, are you letting it come to temp before starting. What temp are you using? Tank anode or conforming? James Watts - Navarre, Florida A. I don't have anything specific to HEEF, but this should work: 1. Soak clean to remove any grease, oil, etc. Rinse. 2. Reverse current in chrome 1 to 2 minutes about 6 volts. 3. Direct current starting at zero volts, then ramp up to full plating current over about 5 minutes. Jeffrey Holmes, CEF Spartanburg, South Carolina

A. John. You cannot do the etching in HEEF 25 solution, but if you have a regular hard chrome plating solution you can do the etching in that solution. Etch for two minutes, don't rinse the area when you move the part from the tank to tank. Let the part take the solution temperature with no current, raise the current to 0,5 A / dm2 for 5 minutes, raise the current once again to 2,5 A/dm2 for 5 minutes. Look at bubbles in the chrome solution they will be a little bigger than when you chrome with right current. Raise the current very slow to the plating current. All activation steps: read Mr Watts suggestion.

Regards

Anders Sundman
4th Generation Surface Engineering
Consultant - Arvika,
Sweden

Thank you to everyone for your responses. I have gotten in contact with tech advisors in U.S and they have faxed me appropriate information very similar to the responses posted. I greatly appreciate your time and efforts to make response. So far the jobs we have tried are working out well. Thanking you again.

Multiple threads merged: please forgive chronology errors and repetition  🙂

Q. Sir,

If chrome plated parts are undersize in grinding then is it possible to replate chrome instead of deplating & then plating?

Thanks for suggestion on my query of chrome over chrome.
I have followed steps & found good result. There is no pull off of plating after grinding.
You have sorted out my major rework problem.

Also I want to know about adhesion testing of plating.

Ed. note: Hi Dhanajay. Please search the site for 'adhesion test chrome', and post your followup questions on one of those threads so this thread can remain being about chrome on chrome. Thanks.

Multiple threads merged: please forgive chronology errors and repetition  🙂

Q. Recently we machined chrome plated shaft ID beyond allowable limits. Can anyone advise me how to chrome plate over chrome without any failure.

Regards

G G