Page 9 - MetalForming January 2010

report that no parts cleaned by the Universal 81C have ever failed a cleanliness test. Durr Ecoclean: 248/960-4630; www.durr.com
How to Cut Cost from Powder Coating Finish
Information provided by Dallas Cooley, vice president of sales, Georgia Powder Coating Inc.; www.georgiapowdercoating.com
I have been in countless meetings dis- cussing problems with powder-coated parts with people who work in purchas- ing, quality control and production. Each meeting typically begins with, “Dallas, what do you think this (problem) is, and how do we prevent it?”
Here I’d like to present some questions each reader of this magazine should ask before a new part that is to be pow- der coated enters production.
• Is there a hole in the part that would allow the part to be hung from a metal hook? The powder-coating process requires the part to be grounded and suspended in air in order for powder application, typically achieved by a metal hook.
• Will the part hold water during the pretreatment process? Will the water run off, or will it build up in corners, areas not welded solid, etc.? This can be a problem, since powder coating and water do not mix.
• Does the part have any crazy angles? Powder coating is an electrostatic process and the coating may not flow well into any corners 90 deg. or tighter. Have a pow- der-coating expert look at the part draw- ing to determine if the part is “powder- coating friendly” to save time and money in the long run.
Once a part enters production, here are key items to look for:
• Do you have overlapping seams not welded solid? This part feature repre- sents the most common problem we see.
Powder coatings will only cover what you can see—this is commonly misunderstood because the process is electrostatic.
• Is the part rusting or oxidized? This may seem obvious, but unless the part is going to be media blasted before powder coating, you must keep rust or oxi- dization off of the parts. One way to do this is to apply on additional water-sol- uble oil to the parts.
• “If you feel it, you will probably see it!” is a rule of thumb that holds true on weld seams, weld splatter, gashes in the mate- rial or any other surface imperfections.
• Does the part have mill scale? Mill scale is a loose coating of oxide that forms on iron or iron products when heated. Be sure to remove any mill scale before coat- ing, as it will prevent good adhesion.
• Carefully remove any residual weld- spatter spray, silicone or any other sur- face contaminants that may not be removed in the pretreatment stage but will bleed through the coating.
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METALFORMING / JANUARY 2010 7