From one to another!
Milling precision for precision tools
For high-accuracy, economical manufacturing of precision tools with batch sizes starting at 1, the Wilhelm Bahmüller company uses a type C 42 U five-axis machining centre from Hermle in its precision tools division.
‘Bahmüller – Invest in Success’ – both the name and the claim stand for highly innovative, top-of-the-scale precision machining for both development and production of special machines and tools. The internationally active Bahmüller Group has around 330 employees and an annual turnover of 70 million euros. A large part of this involves the precision tool division. In cooperation with manufacturers across the globe, this division is devoted to the development, production and selling of precision tools, tool clamping technology and cutting process solutions. This means that the tools are used on modern, high-performance machines requiring high degrees of reliability regarding concentricity, attenuation properties and changing compatibility. Or to put it another way: Some of the precision tools used by a manufacturer or supplier of precision tools are not only manufactured according to their specifications by the Plüderhausen specialists, but provided as process-enabled complete packages.
Searching for partners with the aid of the ‘benchmark tool’
Hans Binder, Manager of the precision tool division at Wilhelm Bahmüller Maschinenbau-Präzisionswerkzeuge GmbH, adds: “We have been gathering competence and specific know-how as well as experience in the development and production of precision tools for over five decades. With our 30-strong specialist unit, we feel we are well set up to exploit the steadily growing market for high-performance special tools, and to this end we have invested heavily in state-of-the-art five-axis machining technology.” Before actually making the investment, the company conducted an intensive evaluation phase in which potential machine and technology suppliers were contacted and confronted with a specially developed ‘benchmark tool’. This included high-precision milling of insert seat / cassette seat surfaces on special tools for exact and secure holding of indexable inserts or cassettes fitted with indexable inserts. Requirements such as this and reliable final / hard machining of heat-treated / hardened tooling steels with HRC 60 proved to be too much for some candidates. In contrast, milling trials on a Hermle five-axis machining centre C 42 U returned first-time success: After a short start-up phase, four out of five milling tests produced acceptable samples of the desired quality!
This was what led to the purchase of the C 42 U five-axis machining centre. To cater for the very high precision requirements, it was supplied with the following extras: Precision package I (X-Y-Z axes) and II (A-C axes), electrical heat compensation, sealing air for the glass scale, tool measuring system, touch probes, ZM 50 tool magazine and larger cooling lubricant tank. With the long traverse paths of X-Y-Z 800-800-550 mm and the 440 mm swivelling rotary table, together with the total of 92 tools, the C 42 U machining centre was able to master all relevant machining of standard and special tools.