Definition - What does Oil Canning mean?
This is the uneven metal flow on the surface of a drawn, thin gauge metal product. It is similar to a two-position twist in a part when the metal tries to relieve these stresses. In metal roofing, it is observable as the deformation that leads to buckling or waviness across the surface of a flat metal sheet or wall material with high width to thickness ratios. Understanding oil canning is useful in providing a better installation method in roofing.
Corrosionpedia explains Oil Canning
As seen from the walls of deep drawn shells (square or rectangular), it is caused by the imbalance of metal flow during a drawing process. It is caused by uneven stresses due to improper installation of a roofing metal sheet. The frequency (amplitude and period) of oil canning will depend on the flat metal sheet width. A larger blank will provide stretch-forming, which prevents the occurrence of this phenomenon.
Since oil canning cannot be totally eliminated or cured by beating or reshaping, it can be easily minimized or prevented by material handling (ensuring that the sidewalls are not subjected to radial compression), proper panel design, material selection (type of metal coil), and the proper installation process; or absorb the stresses developed during a cold-forming production process.
The appearance of oil canning can be enhanced by the viewing angle and the environmental conditions like sunlight and temperature at different times of the day and the season. Since it does not have an effect on system performance, unless it forms from an extreme external influence, it is simply an aesthetic problem.