As a specifying engineer or purchasing agent, you need to find the perfect material to suit your specific job needs, but still want to keep your budget in line. One advantage of roll forming is that it’s the most economical process for shaping certain materials -- especially in parts with complex bends or precise angles.
Almost any material you use for other metal bending processes can be used for roll forming, but not every material is born to be roll formed. When considering alternatives to traditional materials, remember that several processes are applied to sheet metal during production -- rolling, coating, slitting, and so on. The consequences of using the wrong roll formed material can include:
- Production stoppages
- Angry quality engineers
- Unhappy customers
- Lower profits
Those are stress factors nobody wants to deal with!
Good & Bad Materials For Roll Forming
One question we often hear is, “Is my specified material OK to use for roll forming?”
Roll forming metal is a very common practice, so let’s start there. While mild steel may be the most common raw material for roll forming, any ductile metal is considered fair game. Traditional materials include:
- Galvanized and galvannealed steel
- Stainless steel
But every so often we hear about using different source material. Here are some rules to keep in mind:
1) Don’t Use Anything That Has Poor Ductility
You can check out our metal properties PDF chart for a look at ductility and common roll-formed materials.
The top priority for most projects is to build something that’s structurally reliable and won’t fall apart (and fall on people). What makes a material unsuitable for roll forming really comes from a formability standpoint.
2) It Can’t Be Too Brittle; It’s Got to Be Malleable
Anything hard or brittle, like cast metal or certain metals that are heat-treated to increase hardness, isn’t formable.
The most common material we repeatedly see specified even though it’s unsuitable for roll forming is a heat-treated aluminum alloy used for extrusions – 6061. When you’re specifying a T6 or, to a lesser extent, T4, you’re losing bendability, making it harder for your manufacturing to avoid cracking the metal.
That’s why metal extrusion is usually the process of choice for 6061-T6: You need to form and heat treat it at the same time. That’s not possible with a roll forming line.
Non-Metal Attempts at Roll Forming
Someone has to be the first to try something. Here are some non-metal roll forming attempts we’ve heard about:
You can’t roll form foam rubber for the opposite reason you see with heat-treated metals. Something as soft as rubber simply won’t hold its “final” shape after it’s rolled. Next!
Plastic or polymer can be rolled, but it’s usually extruded instead. The problem with these materials is they may bend or break during roll forming.
Certain types of cardboard also can be roll formed, but you have to be careful about the thickness you specify. If it’s more than ¼”, for example, your vendor’s machines will have trouble handling the material.
Helping You Choose the Right Material
Judging a metal (or other material) requires an understanding of the roll forming process itself as well as the properties of the material. Before making a final decision, metal roll forming companies look at the material’s:
- Mechanical properties
- Surface quality
- Uniform flatness tolerances
- End-use requirements
As new grades of stainless steel and other metals come into popularity, we’ll let you know about our experiences with them and whether you should specify them.
As for your current projects, let us know if you’re struggling with material choice or other design decisions specific to converting to roll forming. That way you can make sure you’re fully leveraging the cost-effectiveness and repeatability of roll forming!
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