Equipped by SCHUNKNeed for Speed

For a long time now, rims have been much more than just wheels, choosing the right rims is para­mount for many car enthu­si­asts. The person­ality of modern car owners is not only reflected in the choice of model, but also in the indi­vidual design of the wheels. Whether pink or gold, small or large, simple or eye-catching – there are no limits to your imag­i­na­tion.

ROC Fertigung24 in Freuden­stadt has been turning the dreams of wheel enthu­si­asts into reality since 2017. The mate­rial used is mainly aluminum, at the indus­trial estate on the B294 around 30 tons are sold per month. This results in forged wheels of up to 25 inches in diam­eter. All this variety would not be possible without the exten­sive range of tool­holders from SCHUNK.

Flaw­less rims due to sturdy tools

“Our parts are first turned and then milled,” explains Managing Director Lukas Betz. The basic shape is first turned from a blank on a hori­zontal CNC lathe. This is then machined on 5‑axis milling machines from DMG. In doing so, ROC Fertigung24 relies on a consid­er­able range of milling cutters in a wide variety of sizes. By the end, the finished rims include some highly deli­cate details, all of which also have to have a flaw­less surface finish because the rims are painted.

This means that nothing can go wrong during milling. The require­ments for tool holders and tools are high. “The tool has to be stable for us and have a certain unclamping length. However, long cantilevers are sensi­tive to vibra­tions,” explains Betz. “That’s why you need absorbent holding systems. This is where SCHUNK’s hydraulic expan­sion tool­holders are the right choice because they dampen the vibra­tions.”

ROC Fertigung24 share­holder Tobias Haug concurs: “There is nothing better for us.” With SCHUNK, we have found a partner at an equal level, which is also avail­able for consulting. At the begin­ning of the collab­o­ra­tion, for example, it was not clear whether heat shrinking tech­nology might be the better choice for tool­holders instead of hydraulic expan­sion tech­nology. We conducted exper­i­ments together.

It quickly became clear that, compared to heat shrinking, use of hydro-expan­sion and polygon clamping tech­nology offered a better energy balance on the one hand, and better processing results on the other. An addi­tional posi­tive effect was that the tension could be applied more quickly by means of mechan­ical action. Thus, the numerous tool changes were not only more sustain­able, but also more effi­cient.

Produc­tion in just three days

Because speed is one of the core topics at ROC Fertigung24: “Many of our customers assemble their rims indi­vid­u­ally via our online config­u­rator using their CAD data,” says Mr Betz. “Then, when an order comes in, we get it ready within three days.” This speed is also expected from SCHUNK when some­thing doesn’t fit. “We can count on fast service there,” Betz said.

“Our total tooling concept comes into its own here,” stresses Hermann Winterer, the SCHUNK tech­nical consul­tant in charge, glancing around the machine shop of the rim manu­fac­turer. Betz explains, “We have every­thing here from 700 size jaw chucks to all tool holders, TENDO E compact, TENDO P, TENDO LSS, and a wide variety of inter­me­diate bush­ings increasing flex­i­bility.” The clamping tech­nology compo­nents are used in six DMG Mori DMU75 monoblock 5‑axis milling machines, among others.

Depending on how much or little removal is required, ROC Fertigung24 moves at both ends of the spec­trum when it comes to tool­holders, for example with the small TRIBOS Mini polygon tool­holder for ultra-fine machining or the slim TENDO Slim 4ax for machining close to inter­fer­ence contours. Other SCHUNK clamping tech­nolo­gies are also used at ROC, such as the SINO‑R expan­sion tool­holder and the extremely slim TRIBOS‑S polyg­onal tool­holder. Mechan­ical tool­holders such as ER collet chucks and WELDON arbors complete the manu­fac­turing require­ments.

The right tools for the job

In the case of the TRIBOS Mini, the outstanding dynamic runout of < 0.003 mm is partic­u­larly impor­tant for ROC Fertigung24 — after all, the noble rims demand the maximum surface quality. Micro-blowouts on the tool cutting edge is avoided by the excel­lent vibra­tion damping of the TRIBOS polyg­onal clamping system.

„With SCHUNK we can rely on quick service.“

Lukas Betz, ROC

With the TENDO Slim 4ax, ROC Fertigung24 some­times machines very deep in the Z axis. Rim experts benefit from the fact that it is the only tool­holder in its class with a heat-shrinking contour according to DIN 69882–8. Its robust base body prevents lateral deflec­tion during the cutting process. The enor­mous clamping pres­sure inherent in all SCHUNK TENDO hydraulic expan­sion tool­holders also enables ROC to machine job after job without compro­mising reli­able torque trans­mis­sion. The enor­mous clamping pres­sure creates a displace­ment of oil, grease or grease residue into the dirt groove and the clamping surface remains dry.

When it comes to clamping, the company still sees poten­tial for joint devel­op­ment in the future. Due to the large over­hang of the tool and the depth of the rims to be machined, the clamping table has to be very narrow. At the same time, however, it must also provide perfect support at high rota­tion and centrifugal forces. “Unfor­tu­nately, physics restricts us here,” says Mr Winterer. So far ROC Fertigung24 has relied on a home-grown solu­tion, but is looking to close coop­er­a­tion with SCHUNK. “Of course, it would be better if there was some­thing from SCHUNK,” says Managing Director Haug. “We’re on it,” assures Mr Winterer.