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Ted Mooney, P.E. RET
Pine Beach, NJ
The authoritative public forum
for Metal Finishing since 1989
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Valve mfgr. needs replacement for hexavalent chromate in China and Italy
Q. Our company has to soon be compliant with GMW3056, which restricts the use of Hexavalent Chromate on our parts. I am looking for a substitute for yellow zinc plating (per ASTM B633-85, Fe/Zn 5, Type II) and zinc part with Olive Drab Chromate. They both have to meet a 48 hours of salt fog. Is Trivalent Chromium a good replacement? The parts will be made in Italy and China.
Jeffrey L [surname deleted for privacy by Editor]automotive valve mfg. - Florham Park, New Jersey
2003
A. Probably the easiest thing for you to do is to change the current hexavalent chromate conversion coating to a trivalent version. The trivalent chromates do not exactly reproduce the same colors as the hexavalent chromates, but they are capable of providing 48 hours of salt spray resistance before white rust. I suggest you obtain the latest version of GMW3044, which is the standard that covers electrodeposited zinc coatings (with and without supplemental chromates, lubricants, etc.). It explains the requirements for specifying zinc + chromate coatings. Global Engineering Documents is the official provider of GM standards.
Toby PadfieldAutomotive module supplier - Michigan
2003
A. The hitch with GMW3044 is in section 8, it specifies: Suppliers to this specification must be approved by the respective GM Specialist Teams/TDGs ... Although these approved suppliers are growing daily, I haven't found any overseas suppliers. Additionally our local plater (who in fact could supply to this spec) doesn't see enough Automotive business to justify the hassle of getting approved. Our ad hoc solution has been to specify as ASTM B633 or ISO 2081 with the condition that the coating meets GMW3059. Are there any standards out there that specify trivalent chromates other than GMW3044?
David McNorrillAutomotive Supplier - Aiken, South Carolina
2004
Australian Standard for Trivalent finishes like Corro Triblue + Rogard Sealant?
Q. I am currently writing an internal standard for Trivalent plating using Corro Triblue with a Rogard Surpreme Seal 500 Sealant. Is there an official Australian standard on Trivalent finishes or just the individual motor companies standards like WSS-M21P17 for FORD?
Darren Wrightautomotive - Adelaide, SA, Australia
2005
A. Hi Darren,
As far as I am aware, there are only the automotive specifications at this time (WX100 S437, GMW3044, etc.)
plating - Adelaide, South Australia
2005
Need Barrel Zinc Plating to GMW3044
May 12, 2009RFQ: Must be on GM Approved Sources list. Chicago area.
Dean B [surname deleted for privacy by Editor]hinge mfg. - Brookfield, Illinois, USA
Ed. note: Sorry, this RFQ is old & outdated, so contact info is no longer available. However, if you feel that something technical should be said in reply, please post it; no public commercial suggestions please ( huh? why?)
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