Press Brake Tooling

Warding off wear

By Julio Alcacer, Rolleri USA

Above: Rolleri’s patented Vario adjustable V-die has been designed to handle bending operations for tough materials like abrasive steels.

Precision tooling helps manufacturers bend abrasion-resistant steels with ease, reduce setup time to minutes

December 2020 - The sheet metal fabrication industry has used abrasion-resistant (AR) steels for almost two decades. The material is coveted primarily for its durability and resistance to wear. Understanding AR steels and what it takes to form them is critical for fabricators that want to use these alloys. Precision press brake tooling manufacturer Rolleri S.p.A., Vigolzone Italy, has designed and built precision press brake tooling since 1987. Offering a wide range of products and services for the sheet metal industry, Rolleri has 17 branches worldwide, including one in Avon, Ohio, opened in 2014.

The Avon branch stocks quality-certified precision tools produced in Italy. Through hands-on experience with AR steels and their different applications, Rolleri combines the right tools with education to help job shops harness the advantages of these specialized metals.

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Built with a high-resistance steel structure, the Vario features a CNC control and automatic pneumatic positioning system.

Understanding terms is a first step. By definition, abrasion is the process of scraping or wearing something away. Hardness refers to a property of the material that allows it to resist penetration from another material. Alloys such as manganese, nickel, silicon and molybdenum can be added to AR steels to increase hardness. These steels are then tempered before being rolled and cut into sheet. The harder the material, the longer it is able to resist abrasive conditions.

Ductility is the ability of a material to withstand deformation under traction without cracking. Malleability is the metal’s capacity to withstand compression. In press brake bending, both tensile strength and compression are present. Ductility and malleability are mechanical properties provided in the steelmaking process. Ultimate tensile strength (UTS) is the maximum load to traction before cracking.

Acute angles

When bending AR steel, there are several things to consider. First, there are no unique rules for these materials. To determine thickness/V-die open ratio, the V-die openings need to be at least 10 times the material’s thickness. A fabricator should always ask its AR steel supplier for an empirical chart of instructions for that specific steel.

The punch radius/material thickness ratio is another consideration. Ratios typically start at four times and can go up to 12 or 14 times the thickness. Springback is also a factor. Operators may encounter springback as high as 15 or even 25 degrees. This means tools must be designed with acute angles for acute bends.

Bending with or against the grain is another critical factor. Before cutting the material, an operator must know how the part will be bent and what direction the grain will go compared to the bending line, then choose the appropriate tools and program the press brake accordingly.

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The V-die is designed to resist press brake force from 85 tons to 100 tons per foot while offering 60-degree V openings.

Using a smaller than recommended radius tip punch will cause the material to crack. This is because pressure will concentrate in a section of surface that’s too small. AR steels require larger-radius upper tools so that the pressure is distributed along a larger surface.

Similar complications involve the selection of the correct die opening due to AR steels’ hardness and toughness factors. Using a V-die opening that is wider than recommended to reduce the pressure needed for part bending will result in greater springback. In some cases, the recoil can be strong enough to prevent the material from achieving plastic deformation and the specified 90-degree angle.

However, using a V-die opening that is smaller than recommended in order to reduce springback will increase the press brake force needed exponentially and may result in cracks in the part.

The solution is to bend the part using a V-die opening that respects the ratio given by the steel supplier and make sure the dies have enough resistance to withstand the force the press brake will apply. Such dies will allow the part to have a 15-degree to 20-degree springback.


Fresno, California-based Scelzi Enterprises installed a Cincinnati 750-ton press brake. Fabricating truck bodies in Hardox 450 (an AR steel product), Scelzi needed a press brake with the capability to produce 90-degree bends in material up to 0.375 in. thick and up to 26 ft. long. It added Rolleri’s Vario adjustable die on the press brake, creating the perfect solution.

The standard Vario adjustable die goes from 2 in. to 8 in. and the heavy-duty version up to 16 in. The tooling solution is designed to resist press brake force from 85 tons to 100 tons per foot while offering 60-degree V openings.

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The Vario reduces the force needed for sheet metal bending by 25 to 30 percent.

“Bending Hardox in the Vario is easy,” says J.R. Romagnoli, plant manager for Scelzi. “The die withstands the pressure and we have no problem with the part opening since all the V-die openings are deep and acute.”

This adjustable die moves in increments of 1 in. and can be operated manually or with a CNC-controlled motor. Changing a V-die opening can happen in 2 minutes for a manually operated 20-ft.-long press brake.

The Vario adjustable die was developed to give manufacturers one tool that could provide a number of V-die openings. It was also designed to give AR steel fabricators the ability to bend parts without cracks. The Vario can resist press brake force and eliminate the costs associated with lengthy setup times when changing V-die openings.

Plate fabricators running long press brakes understand the amount of time it can take to change a die to accommodate different gauges. A 20-ft.-long die change could require up to an hour. If an operator changes openings eight times in a week, one entire shift each week is not producing income but simply moving tools around. In the U.S., that adds up to roughly $2,000 a week in lost income.

The Vario adjustable die solves these inefficiencies even with manual operation. One operator can easily change a V-die opening on a 20-ft. press brake in 2 minutes, and be ready to bend thick plate or AR steel right away. FFJ



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