Drag finishing equipment increases tooling life

With eleven manufacturing locations in Europe, North-America and Asia the voestalpine Rotec is a globally operating company that specializes in precision steel pipes and tubes. A member of the internationally operating steel and technology corporation voestalpine, the company is constantly looking to improve its processes.

Hannes Winkler, assistant to the plant manager at voestalpine Rotec and responsible for process optimization, said, “To be able to make our products at internationally competitive costs, our company is utilizing continuous improvement processes.”

Recently, the company focused on increasing the tool life of stamping tools. Even before wear became visible, stamping tools like arbors and die plates had to be replaced because of minor fracturing at the edges. Frequently the edges were reworked by hand. But this did seldom extend the usable life of the tools. With around 50 million manufactured components per year tooling supply was a significant cost factor. Therefore, it was not surprising that the process optimization specialist was looking for an automated, repeatable edge radiusing process for prolonging the service life of the tooling.

Edge radiusing of the tools is an ideal application for the drag finishing technology. This unique mass finishing system allows the precise, targeted surface finishing of high-value, complex work pieces. Exactly defined process parameters guarantee absolutely repeatable finishing results. After considering numerous finishing equipment, the pipe company chose the R 4/700 SF system from surface refinement specialist Rösler. The equipment supplier has international branches, including ROSLER METAL FINISHING USA, LLC IN Battle Creek, Michigan,

“The dry solution eliminated the process water cleaning system required with the wet processing solution,” said Winkler. “This reduced not only the capital expenditure but also resulted in lower operating costs. Of course, the quality and long service life as well as the high availability of the Rösler equipment also played an important role in our decision.”

Automated finishing adapts to different tools

At the heart of the compact, plug-and-play drag finisher is a carousel equipped with four rotary spindles, each spindle allowing the mounting of three work pieces. The R 4/7000 SF systems’ carousel and the rotary spindles are outfitted with separate drive motors allowing the setting of totally different rotary speeds for carousel and spindles. The processing bowl is filled with processing media, which in this particular application consists of crushed walnut shells and aluminum oxide. A vibratory motor mounted below the processing bowl ensures the optimum mixing of the processing media. Required bowl changes can be quickly carried out with a forklift truck.

For the actual process the tools to be finished are manually mounted to specially designed work piece fixtures, which in turn are attached to the spindles equipped with quick-connect couplings. To facilitate this operation, the operator moves the spindles to the load/unload station with the touch of a button.

After the respective processing program has started, the carousel with the spindles is lowered so that the rotating spindles are immersed in the processing media. Carousel and spindles are moving clockwise and counterclockwise at the defined rotary speeds. At the midpoint of the processing cycle the rotary direction is usually changed. This guarantees an even radiusing of the tool edges on all sides. Depending on the tools to be finished, the total finishing time varies between 15 and 45 minutes.

Initially it was planned to use the drag finisher for five frequently used tool types. Hannes Winkler said that the mechanical drag finishing system “produced such good results that the usable life of these components could be practically doubled. And in some instances, it could even be increased by a factor of ten. Since commissioning the drag finisher about six months ago, we have increased the spectrum of work pieces to be finished mechanically to around 20 different tool types. This helped reduce the amortization period to well below two years. By continuously adding additional work pieces, the amortization time will decline even further.”

For more information on the drag finishing equipment, visit www.rosler.com.