Summary for hard-coat anodize touch up Discussion
Hard-coat anodize touch up is discussed as a practical problem for a tool shop that sometimes needs to repair tapped holes or chamfers added after coating. Jeff Frazee asks whether anything can be done short of stripping and recoating the whole part, since he wants wear resistance similar to hard-coat anodize and not just a cosmetic marker fix. Guillermo Marrufo recommends brush anodizing, also called selective anodizing, either by sending the part to a shop that specializes in it or by buying the equipment and training to do it in-house. He notes a key advantage: only the repaired area is affected, unlike strip-and-recoat work. He also warns that stripping and recoating reduces dimensions overall, because anodizing consumes about half the coating thickness from the base material, so repeated stripping can keep removing material.
Q. Dear specialists,
We are a medium sized tool shop with no coating capabilities except your common machine painting, but there are several times we needed to “touch up” some hard-coat anodized parts. Are there any options out there short of sending the part back to the coaters to get stripped and recoated? Usually it’s something simple like a tapped hole or a chamfer that had to be added after coating……. We understand the color may vary a little, but we are looking for something that has similar wear characteristics as hard-coat…… I am pretty sure most people want to grab a sharpie and color the spot in, but that doesn’t work well on working surfaces……. Any suggestions ?
Thank you
Jeff Frazee
Manufacturing – Anderson, Indiana USA
August 28, 2008
A. You should consider brush (selective) anodizing. You either would have to send it out to a shop specialized in brush anodizing or buy the equipment, chemicals, accessories and take the course to do it yourself in house.
An important additional -advantage would be that no other areas but the repaired ones will be affected. Strip and recoat always reduces dimensions overall because anodizing eats about 50% of the thickness of the anodized layer from the base material. Every time you strip you loose at least 50% of the thickness.
Guillermo Marrufo
Monterrey, NL, Mexico
August 29, 2008
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