There are four main metal forming services used in the manufacturing industry today: press braking, stamping, extrusion, and roll forming. Each of these forming methods has distinct advantages and disadvantages, so choosing the best service for your application will rely on quite a few factors.Whether you should use roll forming, press braking, or another metal forming service depends on a number of factors, including (but certainly not limited to):
- Order volume
- Forming speed
- Run length
- Secondary operations
- Value-added services
- Surface appearance
- Part length
- Material thickness & strength
- Shape complexity
Each of the previously mentioned forming operations will perform quite differently for each of these factors.
Metal Forming Services: advantages & Disadvantages
Let's take a closer look at each of the four main metal forming methods, and see what some advantages and disadvantages are that each offer.
Roll Forming Services
Roll forming tooling costs may be higher compared to other forming services, but roll forming allows for more in-line fabrication, medium to large runs, and higher volume orders.
Due to the more gradual forming sequence, roll forming produces extremely tight tolerances as well as an attractive finish. The process allows you to add tooling to create any shape, no matter how complex.
Because the material is coiled and fed through, there are no limits on length.
Roll forming easily handles high volume orders, and is more cost-effective at high volumes. It allows for in-line fabrication (lower labor cost) and can easily form high-strength steels while accommodating for springback.
There are only a few distinct drawbacks to the roll forming process:
- Small orders are more expensive compared to other metal forming services, like brake forming.
- Tooling can be expensive, though tooling costs can be offset in the long term thanks to saving in labor costs on a per-piece basis.
- The roll forming line must be setup by an experienced operator.
- Roll forming produces end flare due to linear stresses, an issue where one end of the part flares outward, though you can speak with your manufacturer about how to control flare as there are many ways to approach it based on part geometry.
Roll forming performs best for projects that require medium to high volumes, tight tolerances, and an attractive appearance. You can learn more about it via the button below:
Press Braking Services
Press braking is both efficient and cost-effective compared to other metal forming options, but only when working with small volumes and shorter part lengths.
A brake press is normally easier to set up than other metal forming services (depending on the number of dies needed for the complete forming sequence). It usually saves you both time and overall cost.
Brake press tooling is also often less expensive than roll forming or stamping.
Larger orders can (and do) get expensive quickly, because the brake forming process is so labor intensive. Brake presses are also unable to handle longer parts due to their relatively small sizes and designs.
Press braking runs into a few challenges in its forming process as well:
- It’s difficult to provide value-added features like holes or punched shapes during the forming process. If your product requires different features or fabrications, press braking may only be the first step in making your part.
- Multiple close bends, angles, radii, and hems are a challenge for press braking, due to the way the press forms the metal. The brake dies aren't made for complex forming.
- A brake press requires an operator (or two for longer parts), and brake press strokes are slow and sequential. So, despite having lower initial tooling costs, the amount of time and labor costs will quickly drive up the overall cost of large orders.
- Press braking is not a delicate process; the force of the die shaping the metal often leaves scratches and tool marks, though if aesthetics don’t matter for your application, then you won’t need to worry about this as much.
- Press braking is not as accurately repeatable as other forming styles, with some referring to it as an "art" rather than a science due to its inconsistency. Tolerances are not as tight as with other types of metal forming, and the final product is very dependent on the accuracy of the steel blank used, and how the blank was created.
Press braking might be an ideal solution if your job doesn't require tight tolerances, if you don't necessarily care about initial appearances, and if you have small order volumes.
Metal Stamping Services
Stamping has been the go-to process for many years due to its ease and affordability.
In addition to being an easy and affordable solution, stamping offers:
- Short cycle times
- The ability to produce complex and fabricated parts
- No need for a skilled operator
Stamping cannot produce long parts, it fights with springback, and it leaves tool marks and scratches on the products.
In addition, metal stamping equipment has difficulties with:
- Multiple lengths being required for the same profile, with each different length requiring a different stamping die, driving up tooling costs.
- Forming long parts, though this can be compensated for by hiring workers to connect two or more pieces.
- Changing stamping patterns; with stamping tools, changes to the punching patterns cannot be made.
- Maintaining low costs in the long term, since the tooling to form longer parts becomes much more expensive than shorter parts.
The cost of metal stamping is highly dependent on your specific project needs. Jobs with shorter parts, parts of the same size, and no need for initial aesthetics may benefit from stamping.
You can think of the extrusion process like a Play-Doh squeezer or a pasta machine. The material is forced through a die while still soft to create the desired shape.
The consistency of the die means an extruded part will have very tight tolerances.
Unlike press braking and stamping, extrusion allows for multiple cross-sections, wall thickness control, and incredibly low tooling costs.
There are four main disadvantages to extrusions:
- There are no value-added activities during the process. Extrusion does not allow for any type of fabrication while the metal is being formed, meaning that any added holes or features require secondary operations.
- It requires a secondary artificial aging process. Since the metal is pushed through the die while soft, it requires a trip through an aging oven once formed.
- Thin parts are a challenge. Although it is possible, extrusion isn’t the best way to form thin parts. As the parts are extruded, they are prone to tangling and deformation.
- It requires a tremendous investment in equipment and tooling. The chemical structure of steel means it's difficult to make soft enough to force through the die, and because of this, steel extrusion is confined to only a handful of specialty companies globally, each requiring high order volumes to take a project.
Extrusion is best for projects with thick walled (.060” +) aluminum, non-steel, non-fabricated parts.
Deciding Between Roll Forming & Competing Methods
We can't stress enough that each metal forming method has distinct advantages and disadvantages, and the nature and goals of your project will heavily influence your choice.
- Roll forming is fantastic for medium to high volumes, tight tolerances, and good looks.
- Press braking gets the job done when you have a small order that doesn't require tight tolerances or a pleasing aesthetic.
- Stamping is a viable option when your part is short, you have multiple parts with similar sizes, and looks don't matter.
- Extrusion is a niche solution for aluminum parts with thick walls that need tight tolerances or multiple cross-sections.
If roll forming sounds up your alley, you might as well do it right. The free e-book below is a great initial tool for understanding how to make a more manufacturable and successful roll formed part:
(Editor's Note: This article was originally published in January 2016 and was recently updated.)
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