From one to another!
Manufacturing special tools economically
How the Czech special tool specialist Hofmeister s.r.o. met its customer's requests for special machining tools economically with the help of Hermle machining centres
Czech made cutting tools and recognised competence in manufacturing of precision parts that extends beyond Czech borders – This brief summary could be used to describe Czech company Hofmeister s.r.o. founded in 1990 by Vaclav Hofmeister. While he concentrated initially on manufacturing injection moulds together with devices and auxiliary equipment for various production industries, his successor Jindrich Hofmeister focussed on supplying the Czech metal machining industry with cutting tools, also providing precision parts. The Hofmeister brothers' company in Pilsen, Czech Republic has about 110 skilled employees today, with about 60 in mechanical manufacturing alone. The other employees are divided into other departments including Sales, Application Consulting, Design, Programming, Logistics and Administration. Hofmeister s.r.o. sees itself today first and foremost as a problem solver for all conceivable tasks related to machining. It is supported by a wide range of standard commercial tools of various manufacturers and also more particularly by its own competence for special tools. CNC manufacturing of precision parts for various segments of industry represents a third mainstay with cross-divisional function, supported by both tool competence and machining knowhow. As such, it offers benefits for both customers and in-house manufacturing at Hofmeister. Hofmeister enjoys excellent standing in the Czech Republic, as attested not least by all the standard QA certifications, a number of awards for intensive training of employees and entrepreneurial performance as well as patents and utility models, for example for a "multifunctional drilling tool".
Synergistic effects recognised and consistently used
Jindrich Hofmeister made it unmistakably clear that these achievements, which are widely recognised today by markets in the Czech Republic, Slovakia, Austria and Germany, are ultimately the result of excellent employees and a highly productive machine park: "When we started with the tool product range, we wanted to build up a well-rounded portfolio so we could meet all our customers' needs. It turned out, however, that we needed more and more special tools to meet the growing demand for higher quality machining, and to be able to do so economically. So we decided to manufacture needs-oriented special tools using standard tools and indexable inserts, and that literally took us into the black. To be able to manufacture special tools economically and at the required quality level, we rely on precision machine tools from Germany, as specific examples two 5-axis CNC high performance machining centres from Hermle. They have allowed us to expand our machining possibilities decisively while at the same time creating capacities that we make full use of with tool manufacturing and machining services in 2 and 3-shift operation". The Hermle C 20 U machining centre was purchased in 2008, the C 40 U in 2011. The C 20 U machining centre, like the larger C 40 U, is especially useful for manufacturing the basic holders of complex special tools much faster, consistently more precisely and above all much more flexibly than was possible before, all thanks to 5-axis technology. The earlier, more traditional approach to manufacturing involved several steps on multiple machines, which naturally resulted in transfer tolerances and with them quality problems, which in turn had to be remedied with added expense for clamping systems, setup, handling and rework.
Complete 5-axis machining of complex tools
"That's not an issue any more today due to complete machining on Hermle machines in most cases," noted Pavel Kozmin, responsible for Development, Design and Quality Assurance at Hofmeister, visibly pleased with the improvement. He and his colleagues in Manufacturing also had high praise for the performance, great flexibility in application and usage and the stability and long-term precision of both Hermle machining centres, the C 20 U and C 40 U. Hofmeister tools and special tools are sold in the Czech Republic through 10 dealers, so every day there are new machining challenges to master. It's a matter of quick response and implementing customers' wishes in a timely manner. This is one of the reasons why Jindrich Hofmeister and his employees decided not only to use two machining centres from Maschinenfabrik Berthold Hermle AG, D-78559 Gosheim that were different in size (working area) but also chose different equipment for the two machining centres. Thus the C 20 U 5-axis high performance machining centre is equipped with an NC swivelling rotary table 280 mm in diameter, a main spindle running at 18000 rpm, 30 tool pockets, the Heidenhain control unit iTNC 530, an ICS system for internal cooling and finally an HSK-A63 tool holding fixture. This machining centre is used for most tool base bodies and challenging customer workpieces, while the larger C 40 U 5-axis CNC high performance machining centre is reserved for machining long overhanging tool holders and special long parts.
Mastering an extensive range of parts with two machining centres.
The Hermle C 40 U machining centre is equipped with an automatic arbour holder system plus expanded pneumatic system to be able to manufacture even very long special tool base bodies and thin, delicate precision parts dimensionally true. The Hermle C 40 U machining centre also has an NC swivelling rotary table 420 mm in diameter, a main spindle running at 10000 rpm, a tool magazine with 38 pockets, an ICS system, a Heidenhain control unit iTNC 530 and an HSK-A63 tool holding fixture. Both Hermle machining centres are also equipped with Renishaw touch probes and tool monitoring/breakage control systems have been added for multi-shift operation to ensure maximum possible process safety and reliability. Jindrich Hofmeister noted in conclusion: "Currently our manufacturing consists of 50% special tools and 50% demanding customer parts, with a growing tendency towards special tools. Because of this we have now expanded from consistently manned three-shift operation, adding minimum operator one-shift operation on the weekend. With the extensive tool magazines already included as standard features in the Hermle machining centres, we are then able to finish complex tool and parts machining with longer runtimes and multi-machine operation on the weekend. This boosts throughput and makes manufacturing more economical, plus customers can have the special tools they ordered even sooner".