“Heat-formed steel” and “cold-formed steel” are two terms that describe the different methods of manufacturing painted steel roof panels.
The photos below are examples of what can happen to cold-formed panels after only a few years of exposure to the elements. And not just roof panels. The photos below are both sidewall panels.
The panels above were made on a cold winter day. And when the flat steel sheets went through the forming process, rather than bending with the steel, the paint cracked.
It was only a matter of time before rust started showing in the tiny cracks.
But it is important to note that cracking doesn’t just happen on cold winter days. The steel needs to reach 50°C – 75°F or else it will crack.
If steel panels were painted after they were rolled out into their unique profile, cold-forming wouldn’t be a problem.
But that’s not how it works.
Instead, the 5-ton coils come pre-painted from the factory.
So what is the alternative to cold-forming?
The solution is to add an extra machine, that we call a heat box, to the assembly line.
In the second it takes for the steel to pass through the heat box, it goes from room temperature to over 50°C!
The oven temporarily softens the paint, which allows it to flex and bend with the steel as it goes through the roll former.