„Productivity increased by up to 80 percent“

EMZ: Boosting productivity in the manufacture of locking mechanisms

With a new B 20K welding controller, emz-Hanauer GmbH & Co. KGaA has been able to boost its productivity in the manufacturing of locking mechanisms for domestic appliances by up to eighty percent. This is possible, in particular, thanks to the servo-controlled movement of the electrode holder, which is therefore no longer linked to the press cycle time.

emz-Hanauer GmbH & Co. KGaA, a company located in Nabburg in the Upper Palatinate in the south of Germany, develops and produces components, assemblies and complete systems that combine elements from the worlds of sensor technology, electronics and mechanics. The components are used in home technology to control heating, water and solar installations, in the field of environmental technology, for example to record waste volumes, as well as in locking mechanisms for domestic appliances. For this segment, emz-Hanauer is the global market leader and provides locking mechanisms and sensors, for example for dishwashers, fridges, washing machines or ovens. The secret behind the success of this family-run company, which celebrated its 70th anniversary in 2018, lies in its very high level of vertical integration. For many years, this has also included its welding operations. “Resistance welding is a very important area for us and one in which we have developed considerable expertise and which we want to keep in-house in the future,” explains the head of the welding shop, Helmut Schönberger. “We are primarily concerned with solid-wire welding on springs or contacts that we then install in the corresponding locking mechanisms that we also manufacture ourselves, for example for washing machines.” emz-hanauer manufactures 25 million components of this type every year.

Independent movement

“In our case, the major challenges in resistance welding lie, on the one  hand, in the large number of different materials used for welding or which we weld onto,” explains press fitter Thorsten Lindhof. “At the same time, we have to deal with components made from particularly thin materials onto which we have to weld contacts with diameters of a few tenths of a millimeter with pinpoint accuracy. Since April 2018, this and many other tasks have been successfully accomplished by the Bihler B 20K welding controller. One of the highlights: The electrode holder can be controlled via the servo motors and is no longer coupled to the movement of the press ram. This means that the holder can be closed even before the ram has traveled fully downwards, for example. “This permits a significant increase in the available welding time per stroke and consequently also leads to higher throughput rates,” emphasizes Schönberger. “In this way, we have been able to increase production speeds by up to 80 percent.” With the new B20K, it is also possible to define the set values more accurately and the welding process is more precise. The quality of welding has also improved.

Convenient and reliable

Other features of the B 20K have proved to be of great value in practical application. These include, for example, path measurement on the closing of the electrode holder, which adds further security to the process. The stored welding parameters can also be set considerably faster than in the past and the touchscreen makes all aspects of operation extremely convenient. Last but not least, the final system check can be performed with extreme precision using the handwheel. The system is then ready to start production, for example of lock contacts. The B 20K uses silver-nickel solid wire to weld the components, which are made from silver-plated brass and copper-beryllium. They are then sealed.

Investing in the future

After just a few days of training at Bihler in Halblech, the B 20K controller was successfully commissioned at emz-hanauer – and even now offers enormous potential for the future: “The new B 20K welding controller is an acquisition that will strengthen our welding shop in the future,” says Schönberger to sum up. “With it, we can optimize the manufacture of our current products and we are also in a position to manufacture completely new products successfully – without having to make any further large-scale investments.”