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Plate Roll forming and Rolling Plate

Variable Geometry Plate Rolling Machine
roll forming process
roll forming

About Steel Plate Roll forming

Steel plate rolling involves passing a piece of steel plate through one or more pairs of rollers in order to reduce the overall thickness of the material. This process also ensures that the workpiece thickness is unchanging throughout. This procedure is categorized according to the temperature of the steel plate being rolled. If the temperature is above the recrystallization point the process is called hot rolling and if below it is called cold rolling.

Hot Rolling

Hot rolling processes have more weight than any other manufacturing process available. Finished products are usually of very high quality but can be left covered in mill scale due to the high temperatures during processing. This oxide is removed via pickling to leave behind a smooth surface. This method is usually employed to produce sheet metal or other materials, including:

  • Automotive parts (frames, wheels, water heaters, etc.)
  • Agricultural equipment
  • Compressor shells
  • Metal buildings
  • Guard rails

Cold Rolling

Cold rolling increases a material’s strength, improves the surface finish and maintains tighter tolerances. However, cold rolling cannot reduce the thickness of material as well as hot rolling can, especially in a single pass. Cold rolled sheets and strips come in various conditions:

  • Full-hard
  • Half-hard
  • Quarter-hard
  • Skin-rolled

Full-hard cold rolling reduces a material’s thickness by up to 50%. Each respective condition then reduces thickness as we go down the list, finishing with skin-rolling that reduces thickness by no more than 1%. This last condition is used more commonly to provide a uniform finish. Common applications of cold rolling include smaller parts such as:

  • Metal furniture
  • Motorcycle parts
  • Lighting fixtures
  • Hinges

2 Tips for Plate Rolling

Tips 1#: The Math Behind Plate Rolling

The plate rolling process entails two groups of important variables. The first group hinges on the machine, such as the number of rolls, their diameter, position, and how they move. All these depend on the machine being used. The second variable group deals with the workpiece involved, such as the maximum plate width (W), maximum plate thickness (Th), and minimum workpiece diameter (Ø), as well as the type of metal and its yield strength (YS). These variables can be plugged into an equation: W x Th2 x YS/g = K, where K is the constant and g is a parameter that takes into account the workpiece diameter and the machine geometry.

Applying such equations requires detailed application information, of course, but the important takeaway here is the factor Th2. Note that the sheet thickness value is squared, implying that a small change in thickness can have a dramatic effect on roll parameters.


The minimum diameter is the smallest diameter you desire to roll your material into because it is a great driving factor for the size of the machine that will be appropriate for your workshop’s certain needs.

There’s a rule of thumb to determine a steel’s minimum bend radius: Divide 50 by the material’s tensile reduction percentage as specified by your supplier. This value will vary by grade.

If the steel has a tensile reduction value of 10 percent, divide 50 by that value: 50/10 = 5. Next, subtract 1 from that answer: 5 – 1 = 4. Now, multiply that answer by the plate thickness. If the material is 0.5 in. thick: 4 × 0.5 = 2. So in this case, the minimum inside bend radius is 2 times the material thickness.

Click for a Bend Radius Chart for aluminum and stainless steel for recommended minimum bend radii.