Different styles of presses are used for a variety of reasons in the metal forming industry. The press that you choose to use in your shop will depend on your industry, your parts, and more factors in the roll forming process. In this post, we will discuss the different types of presses that are used in the roll forming industry.
The Types of Roll Forming Presses
There are three main types of presses that can be used on a roll forming line, and for each of those three categories, there are different styles of presses.
Air pneumatic presses: In the air pneumatic, bladder style presses are common, which have a bladder in between the top plate and the movable ram. Alternatively, there is an air cylinder mounted to the top of the ram or as an under-driven gets pulled down from underneath.
Hydraulic presses: Hydraulic presses are similar to air pneumatic presses in that a hydraulic cylinder could be mounted on the top or on the bottom.
Mechanical presses: Mechanical presses could have a mechanical crank. The crank could be on the bottom, which is an under-driven press — a very popular press in the roll forming industry.
When and why would a customer consider one type of press over the others?
Typically, air presses are the most economical presses for the type of tonnage you can get out of those. As of a lower-cost type of scenario, an air press is the most economical way. A downside to air process is that in the case of a bladder style press, the tonnage rating is at 100 PSI at a half-inch stroke. Most bladder presses can go about three inches a stroke, and the more stroke on a bladder press, less tonnage you get. Just because you have a 20-ton press, you're not actually getting 20 tons. If you use an air cylinder type, you may not be able to get that much tonnage out of that cylinder.
For hydraulic presses, there are a few different styles, including the HHP, which looks like an air press, but just has a hydraulic cylinder, and the HX series where we mount a cylinder on a die. This flexibility makes a hydraulic press a good option for custom work because the cylinder doesn't care which way we cut things: up, down, left, right. An HHP press is about double of an air press in the same tonnage range.
When we get to the mechanical presses, the under-driven presses are fairly expensive compared to an air press and maybe a little bit more than standard hydraulic presses. Regular OEM mechanical presses can be somewhat cost-effective, especially for pre-punching for the bed size that you need and the strokes per minute depending on a combination of some tonnage and the application.
There are certain applications we wouldn't want to do in an air press that would need to do in a mechanical press or a hydraulic, such as forming or embossing. We don't want to do that in an air press because even though there's typically bottom stop ram stops, you don't want to bottom one of those presses out. Also, the speed of an air press is so fast that it could cause some issues in regards to some of that forming. We just take care of it all in the cutoff. We may look at a hydraulic press, self-contained hydraulic press, or a mechanical press.