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"Chrome Plating Steel Parts Scrap Rate"

February 13, 2018

Q. I work in an automotive company and we calculate costs for different parts including chrome plated steel parts like bumpers or grills.

To achieve a good and valid cost calculation we need as much details as possible. Right now I am working on a steel chrome calculator and template. We already include polishing, the electroplating process, material costs and visual inspection.

The problem we have right now is that we know there will be a scrap rate when electroplating steel parts. (From some suppliers we got Information that the scrap rate when electroplating plastics is between 10% and 20% because after the plating process every small flaw in the plastic part can be seen. And they have to throw the parts away) But we assume the scrap rate when electroplating steel is not as high.

Does someone know the average scrap rate? As mentioned above we mostly calculate big parts like bumpers and grills. We really need just an estimation.

Obviously you don't need to throw plating parts away. What is the process to rework an electroplated steel part to chrome plate is again? Or is it possible to polish most flaws in chrome plating steel?

Jelle Boehm
- Portland, Oregon, USA

February 2018

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A. Hi Jelle. Interesting question. In the old days of widespread chrome plating of auto bumpers it was common practice to allow a bumper two tries before it was rejected and scrapped. If it didn't look right on the first go-'round, the bumper was marked, the chrome was stripped, a nickel strike was added, and the nickel plating and chrome plating re-done. If a marked bumper was then rejected it was scrapped. I think the final reject ratio was probably very low (probably about 1% or less) because of this procedure, but obviously a twice-plated bumper costs significantly more that a once-plated bumper anyway.

I don't know current practice, but it would surprise me if bumpers with two layers of plating are acceptable anymore, and it would also surprise me if stripping the nickel off a bumper and starting over is cost effective.

It is possible to polish out some defects like small chrome burns, and I know this is routinely done on certain components like aluminum chain guards for motorcycles, but I haven't seen it done on bumpers, perhaps because the mass production economics are very different.

A final element to add confusion instead of enlightenment is that the percentage of rejects is surely related to the size of the article being plated because one cause for rejects which seems almost impossible to completely eliminate is gas pits. The chance of a large bumper having an unacceptable gas pit or unacceptable area of gas pits is much higher than the chance of a small part suffering that problem.

I hope this discussion continues with some input from current bumper platers :-)


pic of Ted Mooney
Ted Mooney, P.E. RET
Aloha -- an idea worth spreading
finishing.com - Pine Beach, New Jersey

February 27, 2018

A. Hi, Jelle,

Calculating an "average" scrap or rejection rate may be a rather difficult project. There are a number of factors that determine a given part's suitability for a successful re-chrome. Substrate composition and condition are significant factors. Excessive corrosion and pitting on a steel bumper or grille can result in rejections that would otherwise be highly suitable for re-plating. Customer expectations can be a determining factor, as can be the current "book of business" that a given plating facility may have (some facilities will reject "marginal jobs if their current workload is already more than they can handle in an expeditious manner.) With so many variables to consider, you may be better suited to contact a number of different plating facilities to get their specific scrap rates. When you find one that you are comfortable with, use their numbers to complete your template.

Having said that, we generally have a scrap rate of less than 2% when it comes to steel bumpers or grilles. When electroplating plastic, our reject rate runs at 1/2 of 1% ( that translates into a success rate of 99.5%). I cannot imagine why your sources have reported scrap rates of 10-20%. For purposes of your template, you could probably use a 2% scrap rate for either plastic or steel and feel reasonably confident in your calculations/budgeting.

Hopefully, other plating facilities will chime in and share their numbers with you. Good luck with your project.

Mike Robbins
- Las vegas, Nevada, USA

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