Roll forming is often viewed as a cost-prohibitive process for metal fabricators. Typically, metal fabricators turn to stamping, press braking and extrusions for their needs, and roll forming is cast aside without consideration.
Yet roll forming can be the most cost-effective method to achieving a quality product. Roll forming has the ability to reduce your product’s weight, simplify design and cut secondary fabrication needs that can be handled inline.
Even if you’ve never designed for roll forming, it may be time to consider what its capabilities can do for your bottom line. This roll forming guide has everything you need to determine whether roll forming is your best option, manage costs and take the next steps in designing a roll formed product.
Determine if Roll Forming is Right
for Your Design
Before you begin optimizing your roll form design process, be sure roll forming is the best option for your needs.
Roll forming runs coiled metal through a series of roll tooling, which gradually shapes your product into the desired cross-section profile. This is the most effective option for high volume production, rather than one-off parts, like press braking or stamping.
Roll forming has the capabilities to perform inline secondary operations, such as stamping and punching, which also reduces the need for tool maintenance. This process has no length restrictions other than the length of coil fed into the machine, and is able to handle high strength steels with ease.
Stamping uses dies to form shapes from blank metal sheets. Unlike roll forming, stamping may be more cost-effective for smaller productions and one-off parts. This process may incur additional costs if your part is longer than 10 inches.
Stamping is not ideal for high-strength steels and could leave marks from galling and scratching, so you may want to avoid this for finished products that need to appear polished. While lengthy parts could be more costly to stamp, it may be a less pricey route if your part is small and simple, and does not have any holes, trimming or notching. Stamping also typically creates more scrap metal, as it requires blanked sheets instead of coils.
Press braking uses dies to form sheet metal along a straight axis. Similar to stamping, press braking is suitable for small production parts.
One advantage of press braking is its relatively low tooling cost, if no secondary operations are needed. Press braking is often the least expensive metal fabrication option. However, this process tends to be slow, which can drive up labor costs, and the finished product can be left with marks from galling and scratching.
Extrusion is a common engineering fallback due to low tooling costs and its success creating lightweight products. However, for a high volume run or complicated design, roll forming is often a less costly option due to its ability to complete inline secondary operations.
One of the biggest differences between extrusions and roll forming comes down to the ability to execute secondary operations, such as punching. The extrusion process requires the part to endure a secondary aging process in an oven before any secondary fabrication process occurs, whereas roll forming can complete many of these operations continuously.
Length restrictions of extrusion are also trickier than roll forming, which is only restricted by the length of steel coil. Extrusion length restrictions are dependent upon the work piece and its profile.
One last consideration when choosing between roll forming and extrusion is the material strength. Roll forming is able to handle high strength steel, while extrusion mainly utilizes aluminum for its high malleability.
Evaluate Capabilities and Costs of
the Roll Forming Process
Once you’ve chosen roll forming, you’ll need to understand what the capabilities and cost considerations of the process offer before you can begin considering designs.
Choosing the correct material could save money and time off the bat, and understanding what materials are capable of being roll formed is the first step. Aluminum and steel are ideal for roll forming, as they are able to retain their physical properties after being manipulated and conditioned. However, the list below outlines the materials that are able to be roll formed.
- Stainless steel
- Galvannealed steel
Tip: Aluminum extruded products can often be redesigned for roll forming using steel, a stronger metal. This method can lower costs by reducing material needed to achieve the same strength tolerance.
Upfront roll form tooling costs can create a bit of sticker shock, but the long-term savings that roll forming can provide are tremendous.
For those who cannot afford the initial costs, amortization is an effective payment solution. Spreading out the investment of tooling needs allows manufacturers to take advantage of roll forming’s high-volume, long-term production solution for less.
Roll forming may alter your sourcing needs, so be prepared to re-evaluate your current relationships and identify partners that can accommodate high volume production.
An experienced roll form partner can help you evaluate your sourcing needs and identify the best solution.
The high production volumes typical to roll forming allow for smaller margins of error, so manufacturers need to stay alert for overproduction and forecast accurately. For designs with short lifecycles, or for a single highly customized part, roll forming is not ideal.
As you begin to form an inventory management plan for your roll forming project, study your options. Maintaining close tracking of high inventory volumes is essential to eliminating waste.
Consider offsite inventory and management, which reduces the amount of in-house storage space needed, as well as the labor costs. In turn, this allows for higher inventory.
Overseeing Cash Flow
Considering how each factor associated with roll forming will impact profit margins is pertinent to balancing cash flow. Some cost considerations include:
- Raw materials
- Production time
Take the time to add up the costs of every item necessary for the production of your part, as the margin of error for roll forming is small.
Follow Best Practices for
Economical Roll Forming Design
While roll forming opens a whole new set of opportunities for design, there are a few specifications and restrictions it will be best to stick to as you form your ideas.
Be creative with your desired shape. Roll forming makes it possible to produce a part with 7-10 bends, if necessary, through progressive rolling. Don’t restrict your designs.
Consider symmetrical designs, as this is less prone to distortion than an asymmetrical piece.
Design corners with large radii, as the smaller a corner gets, the more it is prone to cracking. However, roll forming can reach a sharper radius than other methods.
Avoid designing deep or narrow channels on your roll formed product, as the can be difficult to achieve with roll forming machinery. Average size machines are typically most effective at forming channels at or less than four inches deep.
Produce a “flower” pattern design that outlines the bend progression of your part.
Utilize roll forming’s unique capabilities to complete inline secondary fabrication processes, such as stamping, punching and cut to length.
Combine part components inline, as well, to eliminate additional tooling, labor and material needs.
In general, keep tolerances loose without sacrificing quality in order to keep your part affordable, and understand fabrication functions that may affect tolerances:
- Multiple bends create multiple angle tolerances that add up, which affect part dimensions and tolerances as a whole.
- Tolerances between holes, while seemingly minute hole to hole, can add up.
- Hole clusters can add to tolerance inaccuracies, as well. In this instance, a single die with multiple punches can be used to reduce inaccuracies.
- Bent holes warp easily, so avoid placing a hole near a corner when possible.
- Inside dimensions may not be as precise as outside dimensions due to strip thickness.
Work with a Roll Form Engineering
Partner and Expert
Turning to help from an experienced roll form engineering partner can save you time and money from start to finish. Experienced roll form engineers thoroughly understand the capabilities and restrictions of roll forming, and can provide the most economical recommendations.
If you’re considering choosing roll forming for your next project, a seasoned engineer in roll form design can add a dash of creativity to the design process, and can, in turn, cut costs through innovation.
Additional Roll Forming Help
Looking for a simple, cost-effective roll form design fast? Or maybe you’re looking for some guidelines. Download the free Standard Profile Engineering Guide to access designs for C-sections, Z-sections, standard hat channels and more.