Where theworld gathers for metal finishing
Q&As since 1989
-----
Paint peel off from alloy wheels
Q. We would like to eliminate the paint peel off problem in Alloy wheel where it is painted with black paint. This happens especially during puncture process where wheels are handled with metallic tools. Is there a CED black painting process for aluminium surface or any of sort of casting in black color?
GOPINATHAN NARAYANANmotor company - HOSUR, KARNATAKA, India
2006
A. Black CED coating can be done on aluminum surface. However, normally it is epoxy base and will chalk with time. You can most certainly try acrylic base CED and that is quite glossy.
But remember paint will be paint and is not meant to sustain the hammering which anyway side mechanic will do.
Mohali, Punjab, India
2006
A. It depends on surface finishing of your raw wheel. If it's good then paint adhere strongly by ED process. Acrylic ED paint will help more in colour retention & chemical resistance so nowadays it is more preferred over epoxy.
Why not you go for black powder as a primer?
Thanks,
- India
2006
----
Ed. note: Full name and city please, cousin. This forum is a place of camaraderie, a dozen Surya's from India have posted here, and we don't know which one of you posted this :-)
Q. We are a manufacturer of aluminum wheels for the automotive industry. We are currently experiencing an issue with paint "peeling" or "flaking" when machined from the spoke of the wheel. When the wheel is clear coated the paint appears jagged. It appears the base paint is "peeling up" and the clear lays it back down but leaving the appearance of a jagged edge. Any thoughts or suggestions? Thanks.
Randy Baucom- St. Mary's, Ohio USA
August 3, 2015
A. Hi Randy. Every layer must adhere properly. Holding paint on in shrink wrap fashion won't work and is an early indication that it won't offer corrosion resistance anyway. It will probably by necessary to do adhesion testing on the base paint, making sure the wheels were properly chromate conversion coated for good adhesion of the base coat to the aluminum.
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
August 2015
UV Additive for Epoxy
on
Amazon
(affil links)
A. Proper surface prep and degrease should lead to good adhesion. Scuffed/sanded/or blasted, with a good epoxy seal prime and acrylic urethane topcoat (automotive paint) from PPG or DuPont is what we use and have zero problems with. The wheels I sandblasted and painted have held up just as long as any powder-coating I've seen and maybe better depending. I've seen some powder-coats turn to chalk with UV exposure.
Brandon Magee- Santa Rosa, California, USA
September 2, 2015
Thanks Brandon. Yes, epoxies will chalk with UV exposure whether they were applied via e-coating, powder coating, or wet. Powder coating, wet paint, and e-coating differ greatly in application method, but much less so in the characteristics of the final coating that is applied.
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
September 2015
Failure in CASS testing of Wet acrylic paint on aluminium rims
Q. We do wet painting on surface of aluminum rims which has been diamond cut polished. so the coating is a liquid acrylic paint sprayed over the aluminum substrate.
Our pretreatment process uses Chrome conversion coating passivation process. the paint is baked to 160 °C x 15 mins. The coating thickness for the clear coat is no less than 35 microns.
We are failing the CASS test.
Please advise root causes.
- Manila Philippines
December 30, 2019
Q, A, or Comment on THIS thread -or- Start a NEW Thread