Lexan PC Painting Process Variation

[cte74]

I have two mating components that are rubbing against one another on tight tolerance bearing surfaces causing a sticking condition. I have DOE'd the issue and nailed it down to variation in the hard coating of a painted Lexan component but can't root cause were the variation is coming from. Is there anyway of process modifications that would cause the skin of the component to anneal or harden during the curing process of the paint? My instinct is telling me that there was variation in the oven curing process that made the skin of the component softer but I can't recreate the failure. My plastic supplier is telling me that nothing has changed but I have seen this issue on one lot only after months of production. Any suggestions or direction would be appreciated.
Thanks,
cte74

 

[yanish]

cte74,
One thing I would look at is the paint used in the process. Lexan is very susceptable to chemical breakdown. If any new chemicals are used in the process, even in small amounts, drastic changes to the integrity of the lexan could be made. If the skin of the the component appears softer, there is a good chance the polycarbonate resin has been degraded.