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How to determine the bending capacity of the plate roller

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Capacity in a plate roll has been well engineered into the design of the machine and careful considerations must be taken most importantly with material yield strength and thickness.

Rolled plates are most commonly used as cylinders, conical shapes; column wraps (stiffeners), bridge supports, or industrial duct systems.

Guide to Determining the Bending Capacity of a Plate Roller

The metal plate can come in various shapes, sizes, and types. A metal plate is essentially a much larger section of a flat bar and can be cut to virtually any width, length, and/or thickness. The plate rolling machine can bend all types of plates including Aluminum, stainless, and carbon steel.

Plates/sheet metal can be made from several different processes and materials. The most common plate is the “universal mill plate” which is designated as A36 material with a yield point (PSI) of 36,000 minimum.

The plate rolling capacity of the plate bending machine is determined by several factors. In order to determine the plate rolling capacity of bending rolls must first determine the hardest yielding material you will be rolling, the thickness and width of that material, and the smallest diameter to which you will be rolling it to.

Maximum bending thickness

The thickness that can roll is tied directly to the width of the plate is bending. For example, the largest plate rolling machine can bend up to 10-foot-wide material x 2½” thick A36 grade material. As the plate becomes smaller in width, it can bend thicker material. But to successfully bend on a plate rolling machine the width of the plate needs to be under the maximum capacity of the plate rolling machine.

Minimum bending diameters

Understand that as a certain capacity plate rolling machine grows in plate width capability the bending rolls, by design, grow in diameter. The larger the diameter top roll the less the diametrical bending capacity of the roll itself. So another factor to consider when plate rolling is the diameter the plate is being rolled to. One cannot roll the plate/sheet metal to a diameter that is smaller than the top roll shaft on the bending rolls.
As a rule, the smallest diameter can easily roll material down to 1.5X the upper roll diameter (with smaller diameters achievable in multiple passes).

Consequences of Pushed Over Capacity

Often operators or fabrication shop owners will push their machines over capacity. Although all plate rolling machines are designed for a range of safety above their designated range, eventually it will damage the machine, and in some cases severely.

One of the first and most common issues with used CNC plate rolling machines is bent rolls. When rolls are pushed beyond their limit over a shorter range of their surface they can be easily deformed.
Another common issue when rolls are overstressed at their full capacity is breaking the top roll at the tapered end that fits into the drop end. This area of the top roll is the weakest and can succumb easily to highly overstressed scenarios.