Eliminating Agglomeration Resulting from the Grinding Process

The investment in a liquid nitrogen cooling system has proven to be a very cost-effective solution to the powder agglomeration problem.

The grinding of solid materials to produce powders is a common manufacturing step found in many industries.In the coatings industry,grinding may be used in the preparation of pigments and of powder coating.Of particular focus in this article is an application solution successfully deployed in the production of powder coating. In the powder coating industry,several different types of polymeric matrices are dealt with.These include epoxies, epoxy polyester ,polyester series , acrylics and polyurethane.

Each material has its own mechanical and physical properties, but, when converting any of them from feedstock chips to ground powder, the friction of the grinding process itself generates a sufficient amount of heat to cause a quality problem resulting from the agglomeration (“clumping”) of partially melted powder particles or heat-induced changes in ground material properties. This problem is worse when the ambient temperature is high.

The quality burden on the manufacturer is two-fold:

• First, it becomes necessary to inspect all batches pro-actively, immediately after processing and again after a short storage period;
• Second, any failed material requires re-processing – followed by a second round of inspection (possibly leading to additional re-processing and re-inspection). The economic and productivity benefits of minimizing – or totally eliminating – the problem are intuitively obvious.