Imagine you apply the brakes of your car. The pads are pressed against the discs and your car is braked. There is a good chance that the brake calliper of your car has been mechanically manufactured with high precision and tightest tolerances on a two-spindle MFZ 2-2 or a three-spindle MFZ 2-3. MFZ is short for the “Horizontal multi-spindle machining centres” of Saalfelder Werkzeugmaschinen GmbH (Samag). Important components of these centres include a gear rim of an exceptional dimension as part of the drive of the tool changer fitted to the machine top, various BRECO® und BRECOFLEX® polyurethane timing belts as well as further drive elements from the Mulco range. Especially for tool changes, the MFZ series offers advantages compared to chain magazines, to a high degree thanks to its high-precision timing belt drive, because its constructive design is paired with a reduced number of movable elements. Due to their high flexibility, Samag two- and three-spindle machining centres for aluminium, cast and steel machining have particularly gained a foothold in the automotive parts supply industry known for its typical large series production and increasingly reduced innovation cycles. In relation to customised machines and transfer lines, the conversion and make-ready times of the MFZ type machines are extremely short.
Standing in front of an approximately 24 ton MFZ machining centre in the Samag production hall in Saalfeld, with the outer cladding not yet fitted, the especially striking feature is the star-shaped tool magazine with its up to 100 (type MFZ 2-2) or 90 (type MFZ 2-3) tools in 10 holders, each with a cassette holder and the attendant tool holder rail accommodating nine plastic holders on top of the machine. Mounting is on an aluminium pulley developed and manufactured by Mulco, with a notable diameter of 1400 mm. It is vertically driven by a BRECOFLEX 100 AT 20 polyurethane timing belt of 4200 mm length.Tool change in 4 seconds
„In the course of machine development, we passed through several stages of drive solutions until we found today’s timing belt drive from Mulco“, explains Dirk Neubert from Samag’s Design Department. The high tensile strength, stiffness and bending fatigue strength of the timing belt are a guarantee for high positioning precision and a fast pick-up tool change in max. 4 seconds. For series production, the individual tools are predominantly called up in the order of the preset program sequence and stored in the tool magazine at their coded positions. As soon as a cassette is finished, the disc magazine is indexed to the next cassette position, accommodated and driven by the huge pulley. The time between cuts during tool changes within a cassette takes only 4 seconds.Dipl. Eng. André Schmidt, consulting drive specialist from the Mulco Partner Wilhelm Herm. Müller GmbH & Co. (Hanover) affiliate in Schkeuditz, stresses the special strong point of drive solutions from Mulco: “Pulleys and timing belts produced by the Mulco Group are optimally harmonised. The same applies to the entire Mulco range, comprising timing belts, pulleys and further accessories the customer requires. We were part of Samag’s development from the design phase on, and made use of the entire range and know-how of Mulco”.
“Fork lift truck principle”
MFZ machining centres from Samag are in demand from medium-sized and large companies, because high flexibility go hand in hand with good value for money. Designer Dirk Neubert counts on innovative, thought-through and technically proven detail solutions: along this thinking pattern, the hydraulic weight compensation of the 3D unit in the heart of the machine weighing more than 2 tons was designed in accordance with the “fork lift truck principle”. 4 BRECO 50 ATN 10 timing belts do the job. According to Dirk Neubert, polyurethane timing belts for this drive application were his first choice, as they not only combine high tensile strength but also absolute resistance to chemical substances, paired with abrasion resistance and excellent length constancy. Also the freedom from maintenance is another significant criterion for use.Hanover, June 2007
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