VCCA Home Forums TECHNICAL - GENERAL Body - Sheet Metal, Paint & Wood powder coating

a while back a friend of mine had a frame and some running gear parts powder coated really looked good . including the springs which he took apart and marked so that would go back like they came apart . we both knew that after a while the coating would ware off even though it is tuff but while talking to some of the local car people i get some mixed reviews . some said that they would not do the springs again as they felt the heat from powder coating caused them to loose some of the tention and sagg . does any one have any experience on this subject . no use in trying if others have had a problem . the friend has not put the body on the frame to check his yet it may take a while thanks

I don't see any reason to powder coat any steel alloy that functions as a spring. You start to change the temper of some steel alloys around 472 degrees F. That is above what most powders flow out. I have a oven that will flow out most powders at 350 degrees after less than 30 minutes. Any real tempering or annealing processes usually start somewhere around the temperature that steel goes non-magnetic whick is close to a very low red, visable in a dark room.

When using the Eastwood powercoating kit, they recommend baking the parts at 450 for 10 to 20 minutes, then curing it for another 20 minutes at 400 degrees.

So far, I'm seeing that the powder can flow as low as 375 degrees... (confirming your comments MrMack).

Bottom line is that you don't want to heat up anyting that is annealed (like springs) if you want them to retain their original function.
Use paint instead.

---Bill

Different powders have different recipes. A common one is 400 degrees for 10 minutes. This means the part must be 400 degrees for 10 minutes, not like putting cookies in the oven for 10 minutes.
Different metals as well as different thicknesses of the same metal can take significantly different lengths of time to reach cure temperature. Most powder coating ovens do not have an accurate method of monitoring the temp. of the ITEM. The operator will GUESS how much longer and hotter he must run his oven to get the ITEM up to the desired cure temperature. Sometimes he is right and sometimes he is wrong. Most powders have 100% overbake tolerance built into them. The powdercoater will often use this as free reign to cook the heck out of your part to make sure he gets a good cure.
If springs can start to lose temper at 475 degrees, I would say that powdercoating, not properly monitored, could be a bad deal.
Our cure oven has a thermocouple which can be clipped onto the part to keep track of its temperature during the cure. Thus, no need for overbake.
I hope this helps.
Mike

thank you guys and doll good info . may be we can get some actual results from someone that has tried it . the powder coating on the springs was done by a comercial coater and by looking at their setup i dont think they monitor their temp. too close and what mike said may apply .

True, I think that a home done powder coat job is done when the powder melts and gets a good flow out, an old electric kitchen oven with a thermostat will get any metal part up to temp fairly fast,

pre heat to 375 degrees and ,,, well just follow Martha Stewart's directions......