“I have been experiencing what I call a surface tension pull problem with epoxies, hybrids and TGIC’s in a 90 degree bend area. I know that it is not a Faraday Cage effect, because the parts are inspected before they go into the oven, and all areas are covered with powder. After the parts come out of the oven, the powder has pulled away from the corner during the cure cycle after the powder has “flowed”. This is evident by the random pattern of separation.
To add to the mystery, this only happens with non-textured powder. My requirements are to have both a textured powder and a non-textured. I need some chemical resistance to the finished product. I have been focusing my energies on trying to identify a hybrid powder. The customer has turned down urethane as an option.
What do you suggest? Thanks in advance.”
“The problem you are experiencing is the result of poorly charged powder due to a Faraday Cage. The powder that you see in the corner before cure is not fully charged and falls from this surface when subjected to heat. This situation has happened before. This is a difficult problem to solve, since you need lower charge on the powder particles to get it to go into the Faraday Cage and then when these lower charged powder particles are put into the oven they fall from the surface.
Here are three solutions:
1.Use a tribo charging gun to coat this area.
2.Orientate the part so that the Faraday Cage is at the bottom and hope the powder flows into the corner.
3.Contact your powder supplier to obtain a powder coating formula with lower flow characteristics. (less flow) “