Curated with aloha by
Ted Mooney, P.E. RET
The authoritative public forum
for Metal Finishing 1989-2025
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Seals wear paint and plating off airbrake components
Q. We are developing sheet metal Ram Assy for air brake systems of commercial vehicles. A tube is welded to a steel formed Ram (drawn part). To avoid corrosion we want to coat the assembly. Problem is that whenever the system is actuated , the tube travels through a plastic seal which rubs the steel tube. Over some period of use , the movement removes any plating or painting we do. Please help.
SHARAD GUPTAPRESCO-MEC AUTOCOMP PVT. LTD. - FARIDABAD, Haryana, INDIA
2004
A. What platings have you tried? Electroless nickel, hard chrome, titanium nitride? Did you try nitriding? Please tell us what happened if these were tried, and what specs you followed in the processing (thickness, etc.) Is it a lubricated application (is there brake fluid or other substance on the other side of the seal)?
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2004
Q. Thanks for your response.
Yes we are trying Arcor coating, i.e., nitriding. But it is costly and commercially unviable. We have not gone for hard chrome as it will also be very costly. There is no fluid on either side.
We are looking for a cost efficient process. We missed to give an information. The tube is grind finish (0.3 microns surface finish) and we need to have 0.6 micron finish after coating.
SHARAD GUPTA [returning]- Faridabad, Haryana, India
2004
A. Hi again. A sketch would help us understand, but you seem to have an abrasive situation in a dry environment, which can't be met with soft surfaces like paint, but require a metallic coating. Zinc plating is cheap, but I'm not yet picturing your situation adequately to know if that is feasible.
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
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