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WORKHOLDING
SCHUNK improves efficiency for gear manufacturer Clamping devices have a significant influence on precision and cost-effectiveness that can be achieved in the manufacture of gearbox components. For maximum flexibility and efficiency of production, Swiss gearbox manufacturer Rollstar AG recently invested in a large six-jaw pendulum compensation chuck with a jaw quick-change system and jaw quick adjustment. The convenient solution minimises set-up times and delivers perfect results right from the start – faster and more economically than conventional clamping solutions. The SCHUNK ROTA NCR 1250 six-jaw pendulum compensation chuck, which Rollstar uses to manufacture gears on a Pittler PV 1600 turn machining centre, is a large-dimensioned chuck with clever features. Christian Märki, Purchasing Manager at Rollstar considers whether it was a worthwhile investment. “Definitely,” he says. “Due to the machine design, including the clamping devices, we were able to reduce set-up times by half while decreasing the reject rate by 75%.” In particular the investment pays off when Rollstar uses the SCHUNK ROTA NCR 1250 for low-deformation clamping of gearboxes.
AMT AUG/SEP 2020
it comes to thin-walled components and high-quality materials. The company’s aim was to achieve the necessary quality levels, reduce throughput times and lower the overall costs of producing deformationsensitive parts in two operations while ensuring process reliability. Due to the SCHUNK ROTA NCR, parts that were previously manufactured on another machine in a three-jaw chuck with a twopressure clamping system are now being produced faster, more precisely, and with greater process reliability. “In the past, when we clamped a ring gear or a ring with a finished diameter of 820mm in a three-jaw chuck, the circularity or cross-sectional tolerance was higher than 0.1mm,” says Märki. “If we clamp the same component in the ROTA NCR, now we achieve cross-sectional tolerances of 0.02mm to 0.03mm. This high-precision increases the service life of our gearboxes even further because the rolling bearings
are subjected to completely uniform loads.” This means that the gearboxes can be used much longer without any maintenance works, and sudden failures are extremely unlikely. Rollstar gearboxes are valued for their extreme reliability in applications such as in tunnelling and mining, where unplanned downtimes would be very costly.
An expertly co-ordinated system The clamping concept has been developed in close co-operation between Rollstar, Pittler and SCHUNK lathe chuck specialists. The necessary range of components, design requirements and set-up times was systematically taken into account. The decisive factor in choosing SCHUNK was the combination of the sixjaw chuck, jaw quick-change system, jaw quick adjustment, and SCHUNK’s ability to deliver quickly. Finally, the testimonials of other clients, which Rollstar visited, helped seal the deal.
