Issue link: https://www.e-digitaleditions.com/i/993770
Finding the right coating technology for a high-volume chain application Q I'm not yet a powder coater. I've been trying to find a powder coating solution to a surface finishing problem. I manufac- ture a small wireformed chain that is 0.031-inch to 0.105-inch in diameter. The chain is used in decorative applica- tions. Several plated surface colors are available (black, olive drab, yellow chromate, and so forth). Recently, a high-volume customer requested some other color options in pastel colors of red, blue, green, white, and so on. I have been to several local powder coat- ing facilities, and none can offer a com- plete coverage guarantee on my chain. The chain has surface contact points that move against each other, which when racked cause the deposited pow- der to slough off before it can be cured. I've heard about an electrodeposited immersion process that might solve my problem, but no one knows where to find the process. This customer would like me to pro- vide about 5,000 to 9,000 feet of this chain in each color option per month. I really need to find a source for this pro- cess or set up one myself to continue to supply to this customer. What sugges- tions can you make? Thanks for your assistance in resolving this matter. G.D., Seabrook, N.H. A Unless a powder person among our readers knows of a method, I would say your information is correct in that powder coating chain is not a good application. You need some type of a plating sys- tem, be it electrocoat, autophoretic, or anodizing. At one time, autophoretic was limited to only black. I have not dealt with this process for some time, so I don't know what is current. You can get e-coats in some colors, but I don't remember ever seeing pastels. That's not to say they aren't available. Anodizing can be done in colors, but again that is not really my bag. —G.T. Measuring powder coating textures Q I would like to know if there is an effective way to specify and accurately measure powder coating textures? I'm currently examining establishment of a world- wide powder coating standard specifi- cation for our company. How do mul- t i p l e p o w d e r c o a t i n g v e n d o r s worldwide control texture? S.H., Greensboro, N.C. A There is no standard for tex- ture in powder coatings. T h e r e a r e s t a n d a r d s f o r smoothness (Powder Coating Insti- tute Smoothness Standards), but these don't cover textures, only different degrees of orange peel. We have even tried to establish texture standards for clients by using surface roughness measurements (that is, media blast profile methods). However, these only provided the height of the texture and not the shape (sharpness or round- ness) of the texture. Therefore, the only accurate way to specify the amount of texture is to use color-panel standards. This means you maintain and supply actual coated test panels that show the color and texture you require for your coating. These standard panels are attached to the purchasing document, along with any other coating performance stan- dards, when you're selecting coatings or contracting for coating services. These standard panels will provide the color, gloss, and texture for your prod- uct and can be matched by the coating formulator or the coating contractor. They should be communicated to both the coating supplier and outside coating contractor, as application variables will affect the texture on your actual product. For instance, the sharpness or round- ness of a particular texture can be influ- enced by the applicator of the coating. Applicators can apply the coating at thicknesses that are outside the range provided by the coating formulator, causing the texture to be remarkably different than expected or formulated. Therefore, even if you have a powder that is properly formulated to provide the amount and style of texture you need, you must be sure that the applica- tor coats your product within stated limits to attain this final texture on your actual product. —N.L. Removing powder coating from reject parts Q Can you tell me what is the b e s t p r o d u c t t o u s e t o remove powder coating, for instance, if you mess up on a part and need to do it over? I have used aircraft paint remover, but it's just not cutting it. Any help you can give me will be appreciated. Thanks. T.J., Paintsville, Ky. POWDER COATING, June 2018 51 George Trigg GRT Engineering Nick Liberto Powder Coating Consultants Questions & Answers