Intelligent Multi-Tumbler solution produces absolutely consistent shot peening results on spring band clips

Quick, efficient and gentle processing of work piece batches

A leading, globally active automotive supplier increases the tensile strength of spring band clips by shot peening. For this purpose the company purchased a second Rösler shot blast machine for its plant in Poland. The Multi-Tumbler RMT 70 shot blast machine, equipped with a highly wear-resistant Rutten high-performance turbine, was designed for fully automatic operation including loading and discharging of the work pieces. A simulation of the work piece behavior provided valuable design pointers making sure that in the actual barrel the work pieces are perfectly mixed. This guarantees the safe and gentle processing of the work piece batches and shortens the actual peening time.

When it comes to developing and manufacturing of automotive components for lowering weights and reducing CO2 emissions, the worldwide active Mubea group is without any doubt one of the global leaders. The company’s products include components for automotive chassis, car bodies and drivetrains. Besides serving the automotive industry, the Mubea group also manufactures components and assemblies for aerospace and home appliances and offers custom-engineered solutions for other industrial applications. With over 700 different types Mubea also markets the worldwide largest range of spring band clips, generally known as hose clamps. More than one billion of these hose/pipe union connection elements are produced at locations in Europe, Asia and North & South-America.

Simulation helps reduce the cycle time for peening of spring band clips
To make these components, manufactured from high-strength alloyed tool steel, more resistant against the constantly changing loads in vehicles, their tensile strength is improved by shot peening them. For this purpose the Mubea Automotive Poland sp. zo.o. purchased a second Rösler shot blast machine. The Multi-Tumbler RMT 70 allows the fully automatic shot peening of spring band clips in batches weighing up to 1,800 kg. A key factor in the customer’s decision for this machine type was the unrivalled geometry of the blast barrel. A simulation of the work piece behavior in the blast barrel provided valuable design pointers making sure that the work pieces are perfectly mixed. This helped shortening the actual peening time. The unique barrel design also helped prevent any rejects by work pieces getting stuck and, thus, helped improve the overall productivity.

High cost efficiency and reduced requirements for maintenance
To comply with the strict specifications of Mubea Automotive Poland, the Multi-Tumbler is equipped with a Long Life Rutten blast turbine with curved throwing blades in “Y” shape and an installed power of 30 kW. The precisely calculated curvature of the blades generates an extremely high throwing speed along with a precise media guidance. This results in an optimal blasting efficiency. At the same time the turbine requires a lot less energy reducing the energy consumption by up to 25 %. The throwing blades are made from a highly wear-resistant alloy, and their special “Y” design allows using both blade sides. For this reason – depending on the used blast media – the Rutten high performance turbines achieve a 10 to 16 times higher uptime compared to conventional blast turbines. This results in a significant increase of the equipment availability and drastically lower costs for maintenance.

An automation concept that is precisely tuned to the customer’s requirements
To completely automate the shot peening process, the shot blast machine was equipped with a special work piece loading system that includes a weighing cell and the required software integration. This allows calculating the optimum batch weight during the automatic work piece load operation. The PLC adapts the shot peening time to the actual weight of the respective work piece batch. Throughout the peening operation the barrel is completely sealed with a lid. The barrel and turbine RPM are automatically adjusted with frequency inverters. All these features, combined with the optimum mixing of the work pieces in the barrel, make sure that absolutely consistent, repeatable peening results are achieved in surprisingly short cycle times. Of course, the continuous monitoring of all critical process parameters also contributes to the process safety and stability.
The blast media recycling and cleaning system is adapted to the overall system and guarantees the consistently high blast media quality required for the shot peening process.