Machining gears with highest precision

Precision boring mill by UnionChemnitz at work

Special gearbox manufacturer RSGetriebe was faced with a challenge that is familiar to many: „The tight tolerances required by us could not be met using a classic boring mill. A jig boring machine was not an option for us – due to the disproportionately high investment costs on the one hand and the limited degrees of freedom on the other,“ explains Thorsten Mehlhorn, President and COO of RSGetriebe. Instead, the gearbox manufacturer in Sonthofen, Germany decided to invest into the precision boring mill KCG 125 recently developed by UnionChemnitz.

The precision boring mill unites the advantages of a classic boring mill with those of a jig boring machine. The accuracy of the new machine tool was significantly increased in comparison to a classic boring mill by the help of various amendments. At the same time, the precision boring mill is characterized by high flexibility. The boring spindle allows for the machining of contours deep within the workpiece.

Comprehensive optimizations

Thomas Grimm, Senior Sales Manager at UnionChemnitz, explains the development of the precision boring mill: „The KCG 125 is based on our reliable planer type boring mills. These offer the best preconditions for highly precise machining results in terms of design. As a result of many small optimizations and the introduction of a special thermal management we have developed a machine concept with which we are the first manufacturer to enter a vacant market segment.“

Several highlights of the machine guarantee the highest precision regarding both positioning accuracy and geometrical precision. Those include optimized ribbing for an increased stiffness of the machine bed and column, linear guideways of the highest quality standards and hand-scraped guides. Various optimizations also result in an outstanding thermal stability of the machine. Among those are ceramic hybrid bearings for the main spindle and longitudinal compensation of the boring spindle.

Precise and flexible machining

RSGetriebe in Sonthofen is a German manufacturer of high-quality special gearboxes for a broad range of industries. The high-performance gearboxes, which are manufactured tailored to the customers' requirements, are used in industries such as the plastics and machine tool sectors or for test stands in the automotive industry. „Our workpieces have to be machined with a precision of under 0.005 mm regarding parallelism and coaxiality of surfaces and boring holes at times,“ says Thorsten Mehlhorn, President and COO of RSGetriebe. In addition to housings for milling units, KCG 125 reliably machines all gear housings at RSGetriebe. Gearboxes with volumes of 1.5 to 2 m3 and weights of up to 6 t can be manufactured in Sonthofen now.

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 says. After the machine has been in operation for half a year in Sonthofen, Thorsten Mehlhorn's summary is positive: „The KG series by UnionChemnitz with its increased accuracy is a very interesting investment option in comparison to a jig boring machine. The machine's precision is nearly identical and it offers much higher degrees of freedom and greater traverse.“

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