Roller Hemming Robot: Hand Hammers to ABB Heads

Every car door, bonnet and boot lid is two steel or aluminium panels held together along the edge by a fold called a hem. The outer skin is bent over the inner panel, and how neatly that fold sits decides how the gaps on the finished car look. A roller hemming robot makes the fold by running a roller along the edge in several passes. This post follows the job from hand work and big hemming presses, through table-top hemming machines, to robot roller hemming and ABB's own hemming tool, with a news hook from ABB's latest survey of car makers.

ABB robots handling closure panels at a hemming station, from ABB's Excellence in Hemming brochure. Photo: ABB

How car panels were folded by hand and by press

On early cars, bodies were built by craftsmen. Panel beaters shaped sheet metal over wooden frames and folded the edges with hammers and dollies, one car at a time. In Philadelphia, Edward G. Budd developed the first all-steel car bodies, and after talks that began in 1913, the Dodge brothers bought 70,000 all-steel open touring bodies from his company in 1916. Pressed steel panels made bodies stronger and faster to build, but every closure still needed its outer edge folded over the inner panel.

Austin 7 bodywork in progress at Queensland Motors, South Brisbane, 1927, with the wooden frame showing. Photo: State Library of Queensland via Wikimedia Commons (public domain)

Mass production moved that fold into hemming presses. A hydraulic press with a die for each part closes the whole flange at once, usually with 60 to 180 tons of force. As the last forming step in stamping, it largely decides the outer quality of doors, hoods and trunk lids. Presses are fast, but each die is made for one panel and costs a lot, and they work best on flat, simple shapes. Inventors looked for something smaller. A 1957 US patent from Aetna Standard Engineering is among the earliest that later roller hemming patents cite.

A steel bodied truck built by the Edward G. Budd Manufacturing Co. in Philadelphia, 1917 to 1918. Photo: US National Archives via Wikimedia Commons (public domain)

Table-top hemming machines came next for medium to high volumes. Like hem dies, they fold the flange in two stages, a pre-hem to about 45 degrees and then flattening, and can reach cycle times as low as 15 seconds, but each machine is dedicated to one panel. An ABB Flexible Automation brochure said more than 150 lines worldwide used its table-top and hem die equipment. Robot hemming patents appeared in the 1990s. A 1993 US patent from Triengineering Company is cited too, and ABB filed for its own folding tool in March 1999. That patent, granted in 2003 to inventor Jan Persson, describes a roller on a pivoting arm whose pressure is set by a gas filled bellows.

A table-top hemming fixture with robots in an ABB closure line. Photo: ABB

How body shops use robot roller hemming now

In robot roller hemming, a standard industrial robot carries a hemming head and bends the flange of the outer panel over the inner one in progressive steps. The force is much lower: Automotive Manufacturing Solutions put it at perhaps a hundred kilograms at the point of contact, against about a hundred tonnes in a press. The same cell can hem several different parts, and small changes in panel conditions can be fixed in the robot program instead of in a new die. With a tool changer, the robot can also apply adhesive or sealant to the hem flange or move panels with a gripper, which links hemming to robotic gluing and sealing.

An ABB roller hemming head mounted on the wrist of an orange ABB robot. Photo: ABB

ABB sells its own roller hemming tool for closures in the body shop. ABB says it can hem doors, hoods, deck lids, tailgates, fenders and sunroofs, and that it can also hem the wheel house, the arch around a wheel opening on the body itself. The tool controls hemming pressure along the whole flange length and is less sensitive to variations in flange angle and length. A library of roller tips lets it reach tight corners. In 2012 ABB's Alan Stapelberg described two head types, one push only and one push-pull that can reach in and hem an inner surface, moving at about 1,000 mm per second on straight runs. ABB says the roller method costs less to buy and maintain than other systems.

ABB's roller hemming head for doors, hoods and other closures. Photo: ABB

In late September 2026 ABB Robotics published its Automotive Manufacturing Outlook Survey of 473 industry decision makers. Of those, 51 percent said EVs and their parts are easier to build than a year ago, 41 percent said EV manufacturing costs had fallen, and makers expect hybrid output to grow even faster than EVs. "Manufacturers are no longer asking whether they can build EVs," said Joerg Reger, head of ABB Robotics' automotive business line. He added that they now focus on building them "alongside other powertrains", and a plant like that needs hemming cells that can switch between panels.

ABB robots moving panels in and out of a hemming fixture. Photo: ABB

Where roller hemming robots go next

Cell layouts are getting more flexible too. American Machinist described ABB roller hemming cells with several robots, where one robot hems the upper section of a panel while others do the sides and bottom. Programs for those robots are planned in RobotStudio. ABB says the hemming path can be programmed offline there, which cuts the time spent programming and testing on site during commissioning. Several robots sharing one fixture also need to be coordinated, the kind of job ABB handles with MultiMove.

A large fleet of robots in the BMW Leipzig body shop. Photo: BMW Werk Leipzig / Wikimedia Commons (CC BY-SA 2.0 de)

For people who own cars, the hem matters at the repair shop as well. When a door skin is replaced after a crash, the new skin has to be folded over the old door frame again, usually by a technician with hand tools, much as panel beaters did a century ago. In factories, pressure control along the flange, as in ABB's tool, helps when a line switches between panels of different shape or flange length.

A hood panel held in hemming tooling, from an ABB hemming brochure. Photo: ABB

The open problems are cost, quality and skills. A roller hem takes longer than a press stroke, so high volume lines need several robots per part. Paul Meeson of Stadco said in 2012 that he had seen robot hemming make 250,000 units a year, and that 50 to 60 percent of a robot hemming investment can be reused when the part changes. The finished hem must look as good as a pressed one, because customers see every door gap. Plants also need technicians who can tune roller paths and pressures and read the data from each cell. Large ABB arms such as the IRB 6700 could carry a hemming head in a new cell as a possibility, with SafeMove zones keeping people clear of the rollers.

An ABB IRB 6700 lifts a solar module for a folding roof at dhp technology. Photo: ABB

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