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sive stress. There are several potential causes. The coil can contain oil canning from the mill. Slit coil can release residual stresses from rolling that cause oil canning. Too wide, too thin or too weak is likely to oil can. Manufacturing machin- ery problems can cause oil canning. Long panels are more likely to oil can. Oil canning can be more noticeable on darker panels than lighter- colored panels. Mishandling panels (dropping, hitting, damaging) can cause oil canning.

Tuschall: Differing thermal forces can create waviness or defl ection, which can be induced by the sun, extreme heat and cold. Installation of panels on substrate surfaces or open framing that are not fl at or the presence of a screw head used to connect a metal stud wall will read through the metal panel and cause defl ection with-in the panel.

MCN: How can oil canning be prevented …

During manufacturing …

Hance: The science of leveling metal strips has two main goals. The fi rst is to make the metal's surface fl at and ripple-free. The second is to neu- tralize hidden internal stresses that cause twist and bow in parts during secondary operations, such as stamping.

Parvin: Tension-leveled coils, standard-sized panel widths that minimize slitting or re-cutting, and re-squared sheet stock. Tension leveling is an additional rolling process to refl atten coil material.

Stermer: Maintain tooling in good working order. Watch for wear on the tooling.

During handling …

Stermer: Use care not to jar the panels. Cush- ion panel transporters with wood or other cush- ioning material. Crates should protect panels.

Hance: Edge handling to avoid buckling pre- vents oil canning. Carrying of panels in the fl at or twisting of the panels during lifting, can induce a wavy appearance to a previously fl at panel. Twisting can occur if one corner of the cladding panel is used to lift the panel or to remove the panel from a bundle.

Parvin: Proper handling is important at every step. Panels have to be handled and lifted in a manner that will not “wrinkle” the panel. Panels should be carried, shipped and stored on edge when practical.

Tuschall: Bundles of metal panels must to be lifted with proper spreader bars and stored on fl at surfaces to keep the panels straight as pos- sible at all times.

Lynn: Proper handling should be addressed in every step of the process from production to fi nal installation. Panels should not be carried “fl at” or lifted by a single corner. Clean gloves and proper footwear should be worn by handling personnel to avoid scuffi ng the fi nish.

During fabrication …

Tuschall: Properly maintained and adjusted levelers, rollformers, cutters, shears and brakes will reduce the waviness prior to fabrication.

Lynn: Metal-forming equipment should be well adjusted, operated within design limits and oper- ated by experienced sheet metal crafters to mini- mize stresses caused by the fabrication process.

installed cost will escalate up. Panel widths that are greater than the baseline will oil can more but will cost less. Stiffening ribs, striated and stucco em-

bossed panel fi nishes assist in the reduction of oil canning. At CASS Sheetmetal, we recom- mend the striated fi nish, which in essence is a series of fl at lines +/ - 1-inch-wide placed into the

Hance: There are “leveling” devices designed to move excess material from the fl at areas to the edges where it might be taken up by a cor- rugation or joint.

Parvin: Make certain that rollforming equip- ment is well adjusted and that suffi cient space and access between the area rollforming will occur—if rollforming is done on-site—and where the panel is moved to the wall or roof requires minimal changes in direction. If the metal is shipped to the job formed, direct access to the installation point needs to be part of the initial project planning. The reduction of oil canning starts with the

selection of high-quality tension leveled steel and producing a panel profi le that balances mate- rial and labor cost effectiveness with desired end-use aesthetics. The market place/industry base line standard is +/- 16 inches on-center for standing seam panels. Panel widths that are less than the baseline may oil can less; however, the


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