How to specify Chrome Plating for fastenersApril 25, 2012
Q. I have some common fasteners (nuts and bolts) that I am wanting to specify the chrome plating for on a drawing. The chrome plating is decorative (corrosion resistant/looks).
We had a small issue with some common purchased nuts. This caused us to look at the fact that we just specify Chrome Plate for the plating callout. Never had an issue in the past, but seeing this made me realize that we should have an appropriate callout on the drawings for the fasteners for the chrome plating.
The base material is carbon steel.
The testing requirements are: 48 hrs 98% relative humidity. Freshwater, not saltwater. With no more than 10% surface showing signs of corrosion or no spot of rust larger than 1/8" diameter. Not too hard of a test.
I want to properly specify the plating on the drawing for inspection and the vendor.
At the same time, I want to make sure that I do not "over plate" the part, causing it to be unnecessarily expensive.
The fasteners will be common fasteners made by large volume vendors in China.
Is the following callout sufficient? Or do you have any suggestions?
Also, I have to make sure that it is RoHS compliant.
Parts are to be nickel chrome plated per ASTM B456 [link is to "Download ASTM Standards" from ANSI.org] Class 1.
Nickel plating shall be 0.00004" - 0.00009" thick
Chromium plating shall be 0.000005" - 0.00001" thick
Chromium shall be Trivalent Chromium (Cr III) for RoHS compliance.
Can you let me know if this is accurate/makes sense?
I was not sure if a base plating of Copper needed to be applied? Assumed no.
Thanks for the help, it has been a long time since I have dabbled in the complex world of plating. Seem to have forgotten more than I had learned......
Product Engineer - Hartford, Connecticut, USA
A. Hi Brian. The first quick thought is that there is a typo there. If your nickel plating were 10x as thick it would still be thin :-)
Ted Mooney, P.E. RET
Brick, New Jersey
A. Yes I see that the nickel is a "bit" thin. Thanks for catching that.
How's about I substitute a nickel callout of:
Nickel plating to be: 0.0008 - 0.0012" thick
Would this make the above callout on a drawing make sense?
- Hartford, Connecticut, USA