05/08/2015

Test run proves decisive

For the production of stampings from high-strength steel with maximum flatness and precision, SKA in Attendorn uses Schuler’s highly rigid fine leveling machine

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Precision stampings not only require cutting-edge press and die technology, but also high-performance levelers: several rollers straighten the sheet metal as it leaves the coil and eliminate any defects – such as cross bows which cannot be completely avoided in production – with the aid of an alternate bending process. The specific requirements for an optimum straightening process are defined by the material and finished component. In order to find the right machine, it was important for SKA and Schuler to define precisely which materials would be used in production for which end products.

“Until the end of the 90s, we used levelers with nine rollers as we used to produce guide rails from relatively soft materials,” recalls Guido Schneider, SKA’s Chief Technology Officer. However, the requirements regarding materials and tolerances for part quality have grown steadily over the years and this necessitated the use of classic multi-roller levelers. But even these machines were not completely suitable for the targeted production portfolio.

Schuler then offered to run tests with different strips of material on a leveler for one day, in addition to providing on-site expertise. “It turned out that the number of rollers was not the decisive factor,” reports Schneider. “In fact, a 17-roller machine with significantly higher rigidity was the better choice for us.”

One year later, in June 2014, the fine leveling machine was finally put into operation upstream of a 400-metric-ton press supplied by Schuler – one of seven at SKA. The overall system not only increased output and part quality, but even decreased energy consumption.

“The line has since been running without any downtime and has not given us any problems,” says Guido Schneider. “Looking back, I have to say that the test day was the decisive factor for us. Schuler proved that the fine leveler could straighten cross bows in exactly the quality we need. In the past, we often had to readjust the die on a press because the material properties changed within a few meters. Obviously, this also depends on the quality of the coil, but the Schuler device can generally balance out fluctuations so well that nothing is noticed in the die or product. I would definitely work together with Schuler again.”