A Comprehensive Guide to the Oil-canning Effect
You’ve seen the commercials for the latest and greatest wide-load trucking technologies that promise to completely eliminate the oil canning effect. It feels like there must be an innovator out there who will find a way to finally stop oil canning once and for all.
What is oil canning in applications?
Oil canning also referred to as distortion, is a warping effect that takes place during the punching process. After sign blanks have been punched from the coil, the edges are rounded off. The shape changes from a flat, straight edge to a rounded edge. The edge can bend outward or inward. The severity of the distortion depends on the order and the direction of the bending. Oil canning becomes more pronounced as the steel is thinner. The thinnest steel available on today’s market—5052-H14—is about .020 in. thick. Unfortunately, anything thinner will result in brittle steel that will break before it bends.
How to prevent oil canning
1) Go for Thicker, Higher-Quality Material – Thicker metal results in less edge rounding, so the roof will be less likely to warp.
2) Plan in advance for Correctly Sized Fasteners – Adequate fastening and a stronger structure are integral to eliminating warping. Fasteners should be sized accordingly, typically using .200 or .250 in. fasteners. Using fasteners that are too large can crack through the thinner steel.
3) Use Punches with High Deflection – If you will be punching through thinner material, choose a punch with high deflection. Punches with a deflection value of .020 in. or less are generally recommended for thinner material.
4) Punch in Accordance with Punch Die Size – Punches should be sized according to the size of the intended die. A larger punch size will produce a weaker structure while a smaller punch size will produce a sturdier structure.
5) Use a uniform supporting material – The supporting material should be determined according to the type of punch being used. For example, if the punch is perforated, you should use a supporting material that is also not perforated.
6) Use a Tooling Material that Minimises Stress Wrinkling – Maintaining a uniform tool surface not only ensures better punching quality but also minimises stress wrinkling.
7) Choose an Operating Speed that Allows for the Clearance of Punches – The punching speed should be set based on the clearance between the punch tip and the bed of the material being punched.