Process

We follow the IS13620 and ASTM775 standards for the process of applying a fusion-bonded epoxy coating to steel bars and it involves four major steps as mentioned below:

Surface preparation: Steel Cleaning Process - Airless (Wheel Blast) Shot Blasting Process.

In this step, the reinforcing steel is cleaned to a near white metal by using the blast-cleaning method. Shots and Grits are used as an abrasive material in Shot Blaster. The shots help in cleaning the surface of the bar while grits provide an anchor (40 – 100µm) to the bar surface.

Heating: Pre Heating the steel bars at a specific temperature

The next step is heating the blasted bars to the required temperature as specified by the Epoxy powder manufacturer (around 230°C) by passing them through an electric induction heater.

Powder Application: Coating - Fusion Bonded Epoxy Coating

The heated bars are then passed through an Epoxy coating booth where the epoxy powder is applied electrostatically. As the powder leaves the gun, an electrical charge is imparted to the epoxy powder particles. These electrically charged particles are attracted to the grounded steel surface providing uniform coverage of the coating. When the dry powder touches the hot steel, it melts and flows over the surface and at the same time quickly gels as a film (200 –300 µm thick) on the reinforcing bars and on and on its deformations while the residual heat cures the coating.

Cooling: Passing through Cooling Tunnel

The coated bars after curing are passed through a cooling tunnel, where water is sprayed on to the bars to cool them. The bars are then kicked off on to the final inspection rack for testing and inspection. The testing on coated bars is carried as per ASTM775 or IS 13620 or as per requirements. The acceptance tests usually conducted include thickness measurements, flexibility test, and holiday test. We will provide patch up compound and brush for cutting bar welding joints and PVC binding wire as an optional.