Letter 36068

384 hour salt spray FAILING-Spec. WSS-M21P17-B3  

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I have submitted parts with Plating Specification WSS-M21P17-B3. The salt spray tests is for 384 hours. Thickness minimum is .00031" (inches). The parts passed minimum thickness and measured @ .00055"-more than the minumum requirement. The salt spray however failed @ around the 200 hour mark.
Is 384 hours acheivable?
If it is, why did these parts fail?

Don Istvan
- Canton, MI, USA

Dear Sir:

according to:
S437 WSS-M21P17-B3 :Electrolytic zinc plate, w/trivalent clear chromate, Leached and sealed, Integral torque control lubricant Trivalent 96W/384R

S437 WSS-M21P17-B3+wss-m4d240-a2(nylon):Electrolytic zinc plate, w/trivalent clear chromate, Leached and sealed, Integral torque control lubricant + type 2 nylon Trivalent

concerning 384R acheivable, I know lots of Taiwan mfg can do it easily!
the products failed @200SST:I think mostly arise from trivalnet Cr and sealer!

Best regards,

Brian Chang
Kaitex Enterprise Co., Ltd - Taiwan

Don:

The WSSM21P17 B3 specification calls out a specific finish that can only be applied by licenced applicators. These applicators are audited on a quarterly basis, and parts routinely pass the both the white and red corrosion requirements, with and without thermal shock.

I suspect the finish you are evaluating is something other than what is approved by Ford Motor Company.

Please contact me for more details

Mike Wyrostek
Macdermid - Waterbury, CT, USA

I'll agree with everyone but would like to point out a couple of other issues. First to Mike: Yes a specific product is specified however, exceptions are frequently granted to products that produce a finsih that passes the performance requirements of the specification. This is partially due to legal issues (I prefer not to be more specific then to say that they revolve around areas of anti trust actions and collusion) and practical respects (the use of only licensed shops would greatly reduce the pool if potential suppliers especially in some geographic areas).
From a technical standpoint, no matter what products are used, if they are not properly applied and the entire plating process not properly operated they will fail. High organics in zinc plated deposits will cause failure to red corrosion. Improper handling of parts will cause failures. Also be sure the testing protocol is being properly followed.

Gene Packman
- Great Neck, NY

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