Panel Appearance
Roof and wall panels are highly visible "appearance" components. Most are fabricated from prepainted coil, so care must be taken to avoid damaging the coil's coating during the roll forming process (see lead image). This is achieved by having enough roll tooling passes and by chromed roll tooling.
In addition, roll forming can contribute to oil canning, which is the waviness in the flat areas of roofing and siding panels. Generally, the period and amplitude of the wave depend on the continuous width of the flat, so that must be monitored closely. The panels need to be straight, especially on the sides of standing seam panels, so that they can be joined. Therefore, flare must be minimized.
R, A, AG, and other panels run on wide roll formers (44- to 48-inch-wide roll space mills) that produce a panel with 36-in.-wide coverage. The most common standing seam panel widths are 12 and 18 in., and there is no center forming. To change widths quickly, you can produce standing seam panels on a duplex-style mill. The panels also can be run on conventional, raft-style roll formers. Portable mills have made big inroads in this market, because contractors can produce panels on-site, oil canning and all, and put them right on the roof.
