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Hemming tools are among the most popular press brake tools that manufacturers produce. They are available in standard, modified standard and custom-designed tools for particular applications. Hemming tools not only create a safer working environment in the press brake, they also cut manufacturing time by reducing or eliminating part flipping, part handling, secondary machines/operations, and provide a more ergonomic way to form parts. Hemming tools can also greatly reduce press brake set-up times and reduce costly scrap.

However, with so many hemming tool options, you might be unsure which one is best for your application. Let’s explore what types are available, the bends they excel at, and what their limitations are.

Know What Hemming Tool is Right for Your Bend

Solid hemming tools have no springs and are a part of Mate’s standard product line. They can be easily programmed into the machine controller and offer inexpensive, flexible hemming. The main advantage of a solid hemming tool is that it can be offered in fractional sets. Fractional sets offer an advantage over spring-loaded tools because they can form hems within the sheet metal part itself. A 24-degree tip allows for tighter bend angles than conventional hemming tools. Solid hemming tools can also bend parts without the fluctuation caused by springs; so, in essence, you can use these tools to make forms outside of the “hemming application.”

While solid hemming tools have advantages, they also have drawbacks. They require a longer stroke to flatten the part under the punch, which can require more manufacturing time. It’s also generally harder to produce down-flange bends/hems and a smaller flattening area. However, because they can reach 24 degrees and with a knurl on the flattening surface avoid part slippage, a solid hemming tool is better than a non-knurled flattening set.

Spring-loaded hemming tools are the most common and perform best overall. While there are some exceptions, spring-loaded hemming tools cannot be fractionalized since they contain springs and pockets. Spring-loaded hemming tools can handle front and back thrust on the tool and machine ram much better than solid hemming tools. Unlike the solid hemming tool that flattens the part using the punch, the die in a spring-loaded hemming tool flattens the sheet metal edge. As a result, they are far more productive and safer to run than a solid hemming tool. Standard spring-loaded hemming tools also come in a variety of “relieved” die configurations that allow for “more desirable” down flanges, with other features bent close to the hem.

Staged hemming tools refer to a bend operation in which a hemming tool is split into two separate tools: one for the acute bend and another strictly for the flattening operation. Until the invention of spring-loaded hemming tools, staged hemming tools were the most common for hemming operations. Staged hemming tools can still be the least expensive, most productive and simplest way to hem. Some companies use two brakes to achieve this operation. By using a roller between two machines, you can create an assembly line to maximize production. If two machines aren’t possible, then a single stacked hemming tool is most often used in place of the stage tool set. It is also possible to design and stage a spring-loaded hemming set with other “V” dies and punches.

Pneumatic hemming tools use air cylinders instead of springs in the hemming tool. This is an effective way to allow the machine controller to determine when the tool is in its open or closed position. The biggest advantage of pneumatic hemming tools is that the bottom die can rest in the closed position until required, allowing the tool to act as a regular die and create consistent bending. This makes pneumatic hemming tools more productive and attractive in settings where the machine constantly hems in and out of regular bends. Many brakes now have this feature built into the machine itself right from the factory. They can be designed to keep the hemming unit in the machine while the tool remains in the “bottom” position, allowing it to become a die holder where standard “V” dies can be used in a tang slot.

Integrated Machine Hemming is a setup in which manufacturers integrate the hemming feature directly into the machine bed. Some manufacturers also build a moving bed that allows the dies to have a plate bolted onto the die face, creating the effect of a solid hemming tool integrated into the tooling. Integrating hemming into the bed allows only full-length hemming and “window hemming.” The moving bed system allows fractionalized bending and is a low-cost tooling option, making it very attractive. If you make a lot of hems, highly consider this type of machine/brake. This is especially true for industries such as hospital and restaurant equipment, where safety hems are required on part edges.

Modified Standards and Custom Hemming Tools are custom-designed hemming tools for a specific task. Custom hemming tools remove many secondary operations, free up machines, reduce or eliminate part flipping, and offer safer operation than “homemade” tools. Many custom hemming tools can integrate multiple functions and bends into a single operation.

Your Mate fabrication specialist can meet with you in person to help you determine which hemming style is best for you and which machine is best suited to your manufacturing needs. Your Mate Fabrication Specialist can show you opportunities to create a safer work environment, increase workflow, reduce scrap, and, in turn, increase profitability!