The coil coating process
The metal substrate (steel or aluminium) is delivered in coil form from the rolling mills. Coils weight varies from 5-6 tonnes for Aluminium and up to 20 tonnes for steel.
The coil is positioned at the beginning of the line, and then unwound at a constant speed, passing through the various pre-treatment and coating processes before being recoiled.
Two strip accumulators found at the beginning and the end of the line enable the work to be continuous, allowing new coils to be added (and finished coils removed) by a metal stitching process without having to slow down or stop the line.
The following steps take place on a modern coating line:
- Mechanical stitching of the strip to its predecessor
- Cleaning the strip
- Power brushing
- Surface treatment by chemical conversion
- Drying the strip
- Application of primer on one or both sides
- Passage through the first curing oven (between 15 to 60 seconds)
- Cooling down the strip
- Coating the finish on one or both sides
- Passage through the second curing oven (between 15 to 60 seconds)
- Cooling down to room temperature
- Rewinding of the coated coil.
Copyright AB Wilh. Becker