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Chrome Plating (ASTM B604-91) Specification Questions

October 10, 2012

Q. Hi All

A quick bit of background. My company currently manufacturers products for the marine sector that require plastic chrome plated parts, up till now we have just specified platable ABS with a finish of chrome plating. As these parts are exposed to the marine environment you can guess that the durability of the various parts has been somewhat variable!

I've been researching standards and it seems that ASTM B604-91 service condition SC5 is the standard we want to achieve, however I have a few questions regarding specifying this:

1. There are three type of chrome plating methodologies mentioned in the standard, micro-cracked, microporous and regular, I am unable to determine the advantages / disadvantages of each one.

2. In the ordering information section of the specification, nowhere does it specify that you need to specify either double or triple layer nickel and the classification numbers have a d which it says stands for double or triple layer nickel coating. Is the layers of nickel coating intrinsic to the classification number or do I need to explicitly specify it?

3. Microporous Nickel coating, other posts I have read on this site specify that for the best environmental protection the last layer of nickel should be microporous, I wasn't sure if the Nickel compositions specified in B604 for the top layer was microporous and if it's not do I really need to worry about it?

4. CASS testing, we have only ever performed normal salt spray testing on our products for a duration of 28 days. ASTM B604-91 specifies CASS testing for three 16 hour cycles, I have no reference to how harsh this is, I was wondering if anyone knew how long exterior automotive parts are subjected to CASS testing?

I realise this is a long post and I appreciate any feedback you can give.

Thanks

Grant

Grant Ottaway
- Auckland, New Zealand