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Avoiding peeling in painting aluminium castings for motorbikes

Motorbikes components in aluminium casting alloys suffer peeling of the present coating (one layer of polyester). The components works at about 130°C and are exposed to weathering and pollution. What kind of coating system may be recommended? We were thinking to silicon powder coating applied over a surface prepared with conversion coating.

Andrea Vecchi
engineering services - Carpi, Italy
April 21, 2010

Hi, Andrea; chromate conversion coating is ideal. Look into RoHS-compatible trivalent chromates per MIL-DTL-5541 [⇦ this spec on DLA].

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Ted is available for instant help
or longer-term assistance.
April 21, 2010

For years we supplied 500 kls per month to a company coating aluminium casting for motor car cylinder head covers. I would imagine that epoxy although it tends to chalk (don't motorbike enthusiast always clean their bikes on a regular basis?) has superior adhesion and is the only powder you can grind back to the metal (show off lettering) without edge cracking and in addition has excellent corrosion resistance.

Terry Hickling
Birmingham, United Kingdom
April 21, 2010

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