Metallurgical fact: The temper of most aluminum alloys are changed anytime the temperature exceeds 300 deg. The temper clock starts clicking when the temperature crosses through around 300 deg. and clicks faster the higher the temperature is raised. Most paint powders require the temperature to be above 400 deg F. for at least an hour.
It is unfortunate that your Powder Coater did not have the integrity and or the experience to tell you this fact before he took your money. I have seen this happen hundreds of times over the years and have made posts on this forum warning of the consequences of the powder coating. Most of the powder coaters in the Phoenix area also do not believe and will deny that they are ruining parts with their process. Again, NEVER POWER COAT ANY PRECISION ALUMINUM PART!! There is nothing you can do once the part has been cooked and the dimensions are altered by heat treating.
A powder coater down the street from me ruined a bikers Harley heads. The biker confronted the owner of the powder coat shop and wanted him to buy him new heads. The powder coat shop owner told him to get lost. The bikers came back, wrecked his shop and put the guy in the hospital. This shop never reopened.
Another power coat shop ruined a batch of aluminum parts that one of my customers manufactures. The customer took the powder coat shop to court. The court awarded my customer over $10,000.00. This shop closed its doors.
Also, the baking process that many automotive engine rebuilders are using to clean engine parts also changes the temper and alters the dimensions of the heads, engine blocks that they clean. This process raises the temperature of the components that they clean to around 600 deg. F. Most of the guys that are using these cleaning processes and the companies manufacturing the cleaning equipment are uninformed and not aware that they are changing the metallurgical properties of parts they are cleaning!
