MMC Roll Form

The Roll Forming Process: Step-by-Step Guide

Ryan Hernden

This guide covers all of the steps in the roll forming process, from material preparation to punching and notching. Read on to learn more!

A Strip of Aluminum Going through a roll forming press

Roll forming is a fast and cost-effective method of turning flat metal strip into hollow and semi-hollow shapes like cable supports, shelving and racking system components, and even gutters.

This process is often chosen for making lengths of ferrous and non-ferrous angle, ‘U’ section channel, and more complex forms. Holes and other cuts can also be added to increase the utility of the shapes being made. The process can be complicated and, like any manufacturing process, requires thoughtful planning regarding material selection, the number of presses needed, and more.

This blog post highlights the general step-by-step process of roll forming, but keep in mind that roll forming manufacturers will integrate their own unique technologies and methods.

1. Material Preparation

tin alloy rolls

The raw material for roll forming is flat strip metal, which is rolled to a set thickness at the mill before being coiled for delivery.

The coil is slit to the width needed for the product being made and is re-coiled either at or before reaching the roll forming manufacturer.

Keep in mind that rolling puts a very slight camber on the pre-slit coil, and depending on which part of the original coil the material was slit from, the material can have a slight taper across the width. The width can also vary slightly, depending on how well the strip was slit. These factors can influence the shape of the finished product, so it’s important to partner with a roll former that is careful to use only quality material.

2. Material Feeding

metal coil being straightened with a decoiler

Roll forming lines vary based on the manufacturer, but the first machines in a line are the decoiler and straightener. Once the manufacturer receives the pre-slit coil, it’s mounted on the decoiler and fed into the straightener, where the material is straightened and smoothed out.

Alignment is critical when positioning the coil on the decoiler and feeding it into the straightener. If the strip is not precisely centered and aligned with the roll forming stands, several problems could occur. The primary problem is that the bends won’t be positioned correctly, and the rolls will apply a lateral deformation that twists the profile out of shape. Producing high-quality section depends on getting this step of the setup right.

3. Progressive Bending/Shaping

Roll forming a complex profile

Once the coil is straightened, it’s ready to go through roll stands. Each stand consists of a pair of (usually) horizontally mounted rollers arranged one above the other. These are separated by a gap just large enough for the strip to pass between them. These rollers have a profile machined into them. As the strip is pulled through the gap, the profile bends the strip up or down as needed.

It’s not practical or desirable to apply the entire deformation needed at a single roll stand, which puts a lot of stress on the material, potentially resulting in warping, work-hardening, and/or cracking. Doing this would also place unnecessarily high loads on the forming rolls and wear them prematurely. Instead, the roll forming machine consists of multiple stands, each of which applies part of the total bend required.

For example, if the goal is to form metal strips bent at a 90-degree angle along their length, each roll stand might apply a 10-degree bend. Notably, most metals, particularly steel, have some elasticity that makes them spring back to their original shape. Thus, achieving a 90-degree angle might require overbending the strip by 10 degrees. (The exact amount of overbend depends on the elastic modulus of the material and is determined during roll design.)

While most sets of rollers in the line are on horizontal axes, others can be mounted vertically or at angles. These will apply additional bends, potentially even folding over the outer edges of the strip to create a hollow section.

The complexity of what can be produced on a roll forming machine depends on the number of roll stands and the properties of the material being shaped. With more stands, a line can put in more bends and can provide the more gradual deformation harder, more strain-resistant alloys need.

4. Punching, Notching, & Holes (Optional)

A machine is punching holes into sheet metal

Many of the products made by roll forming work better and are easier to install if they incorporate holes, notches, and other cutouts. These can be put in after the product has been formed and cut to length, but doing so risks compressing the shape. There may also be significant part-to-part variation unless some tooling is made for the purpose.

A more practical alternative is to put these features into the strip while it’s flat. This is done at a pre-punch press. As with other metal punching operations, this uses matched pairs of punches and dies to shear through the sheet. Where it differs from other punching operations is that the strip is in constant motion because stopping the strip would slow down the process and create challenges in how the metal deforms.

To deal with this, the press tooling moves in the same direction as the strip as it goes up and down. Punching frequency is set by the spacing needed between features in the finished strip and the speed at which the strip is moving.

If every piece being formed needs the same cutouts at the same spacing, pre-punching is the logical way to put them in. However, if each piece being formed and cut needs something different, punching may make more sense as a secondary operation after roll forming.

5. Cutting to Length

a worker inspects a roll form metal part on a factory floor

As the rolled profile emerges from the last roll stand, it may go through a straightener to take out any camber, bow, or twist that has developed. (These problems are more common with asymmetric profiles.)

The final operation is to cut the profile to length. This is done with either a fly cutoff saw or hydraulic shears. As with the pre-punch press, to avoid any buckling or bending, these move with the strip, synchronized to its speed, as they work.

6. Learn More From MMC

MMC Roll Forming is an industry-leading manufacturer with over 50 years of experience producing custom roll-formed products. Our 14-roll mill setup allows us to perform up to 21 passes for complex profiles and consistent cross-sectional shapes. We also have in-house pre-piercing, cutoff, and notching operations, as well as offline fabrication and assembly services.

Please contact us today to learn more about our unique process and capabilities, or visit our blog for more roll forming resources.

© 2025
 MMC Roll Form. All Rights Reserved.