To increase the vertical range of manufacture in its own facility, RSGetriebe invested in a new machine tool. The goal was an expansion of the production capability in order to reduce the need to buy in components from third-party suppliers. “In addition to the size of the workpieces that are to be machined and the necessary cutting capacity, flexibility in particular was an important factor. On the one hand, the objective was to be able to machine as wide a range of workpieces as possible – not only milling unit housings, but also all gearbox housings. On the other hand, we especially needed better accuracies for the milling head production“, reports RSGetriebe’s President and COO Thorsten Mehlhorn. Some of the workpieces have to be machined to tolerances of less than 0.005 mm, especially as far as the parallelism and coaxiality of surfaces and boreholes is concerned.
„The accuracies we need cannot be achieved on a conventional boring mill – at least not without a suitable measuring strategy,“ explains Thorsten Mehlhorn. With the KCG 125 made by the boring mill manufacturer UnionChemnitz, RSGetriebe has found a solution that reliably achieves these accuracies, without having to make a costly investment in a jig boring machine.
The precision boring mill KCG 125 made by UnionChemnitz unites the advantages of a classic boring mill with those of a precision machine. The precision of the newly developed machine tool could be increased many times over compared to a normal boring mill thanks to comprehensive optimization measures. At the same time, the precision boring mill is characterised by a high degree of flexibility. Even contours deep within the workpiece can be machined with the boring spindle.
A number of machine highlights guarantee the highest possible precision, both with regard to positioning accuracy and to geometric accuracy. These highlights include optimized ribbing for greater rigidity of the machine bed and column, the use of linear guides of the highest accuracy classes and hand-scraped guideways. The increased table stability (GGG50) along with the precision-ground table surface allow for the most challenging of workpieces to be machined. Furthermore, high precision measuring systems are used in all machine axes.
Thanks to all of these measures, even the most challenging of workpieces can be machined with repeatable precision. The new precision boring mill has been in operation in Sonthofen since March 2015. In addition to milling unit housings for boring mills, all gearbox housings are reliably machined at RSGetriebe with this machine. Gearbox sizes with a volume of 1.5 – 2 m3 and weights of up to 6 t can now be manufactured in Sonthofen.
A particular challenge that the boring mill faces at RSGetriebe is the mix of different materials that have to be machined. UnionChemnitz therefore equipped the precision boring mill with wet and dry machining capability accordingly. „With these two machining modes, both steel and cast iron workpieces can be machined, which greatly extends the fields of application of the KCG 125“, says UnionChemnitz’s Senior Sales Manager Thomas Grimm.
In order to ensure stable temperatures during the machining process, the precision boring mill is equipped with an air-conditioned housing including a roof and an extraction system. Therefore, even larger temperature variations in production halls do not affect the constant machining conditions. An operating platform is situated within the air-conditioned housing. “From here, the work area is easily accessible and the whole process can be monitored manually. That is a great advantage for our machine operators in their everyday routine,” Thorsten Mehlhorn observes.
Since efficiency is an important factor in the manufacture of gearboxes, a pick-up station for changing heads has been installed. The tool changer has 60 pockets. The switching of milling tools takes place fully automated during the machining process. RSGetriebe’s President and COO Thorsten Mehlhorn: “Thanks to the pick-up station, the automatic tool changer and the different milling units, we have significantly reduced process times.”
„We custom-manufacture all gearboxes to meet the customer’s specific requirements. Even the basic configuration covers a large variety of applications. If necessary, they are flexibly adapted by our engineering department”, Thorsten Mehlhorn describes the production process at RSGetriebe. From cutting the materials to size to the gearwheel itself, all components pass through the ISO 9001:2008 production process. The depth of production at RSGetriebe is around 75 %.
Thanks to the precision boring mill, this vertical range of manufacture could be increased even further. „We have to buy in fewer third-party components. Furthermore, we have considerably improved the quality of our workpieces while simultaneously reducing the cost per unit. Thanks to the greater degrees of freedom, we have been able to greatly improve the setup times“, says Thorsten Mehlhorn.
Accordingly, Thorsten Mehlhorn’s conclusion is very positive: „The KCG Series from UnionChemnitz with its increased accuracies is definitely an interesting investment in terms of price compared to a jig boring machine. The accuracies achieved by the machines are almost identical, but the KCG provides a much greater degree of freedom and greater traverse“.