Epoxy coating plants commonly coat bars that are pre-cut in straight lengths of around 40 to 60 feet. The bars are then cut and bent to meet project specifications. The bars are carried through a conveyor system and subjected to the epoxy coating process.
To prepare steel surfaces for the epoxy coating process, blast cleaning is done to remove rust, scales and other contaminants from the steel surface. The end result of blast cleaning is a rough surface finish called a profile. The profile increases the effective surface area of the steel and provides better anchorage for epoxy coating when it is later applied to the steel bar.
Blast cleaning involves the release of compressed air on to the steel surface, propelling abrasives like steel grit, garnet, or coal slag to hit the surface, resulting to pock marks that cleanses and roughens the surface.
After the rebars have been blast-cleaned, they are heated and sprayed with dry epoxy powder. When dry epoxy powder is ejected from spray nozzles they are imparted with electrical charges that are automatically attracted to the already grounded heated bars. The dry powder melts and flows into the steel’s heated surface, anchoring to the ribs and deformations in the surface. The heat also induces a chemical reaction that transforms the epoxy powder molecules into complex cross-linked polymers, forever changing the material into its final state.
A 30-second curing process solidifies the epoxy coating, with an air or water quench introduced to reduce the temperature quicker for easy handling.
The process of manufacturing epoxy coating, and the coating process itself, are efficient and environment-safe, with little material lost to the atmosphere, even lesser waste, and zero contaminants. Because of the environmental consideration and to comply with environmental safety standards, epoxy coating remain a viable choice to protective coating.