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Flexibility – a must for measuring fixtures and suppliers


Building accurate measuring fixtures for different workpiece shapes and sizes using modular fixturing system Alufix.

Manufacturer Witte (Germany) and Witte Far East (Singapore) have continually extended this system made of high-tensile aluminium and have themselves developed into a system supplier. They are increasingly designing and assembling complicated fixtures like inner and outer meisterbocks as well as cubings for automobile manufacturers using special CAD tools like the parts library Fixmes and the design software Alufix-Expert.
The rising need for measuring fixtures in the automobile industry primarily originates from an increased demand for quality, not least of which are ISO requirements, whereby proof of accuracy in checking equipment is one of the most important. As a result conventional gauges with accuracy of only +/- 0,5 are being replaced by more accurate fixturing systems. These are checked together with the workpieces on high-grade measuring machines so that defined statements about fitting accuracy of the body parts can be made.
The increased quality requirements have led Daimler Chrysler, Bremen, (amongst others) where Alufix has been used since the middle of the Eighties, to increase their use of modular measuring fixtures.
„Our experience with this system was already good for the W202, predecessor of the C-class. Meanwhile it has been extended so that for almost every clamping situtation we have the matching Alufix part“ Engineer Paul Bockhorst, responsible for control planning in the body in white/press department at Daimler Chrysler, Bremen, praised the Witte system.
Right now Alufix is being used for measuring underfloors and sidepanels of C-Class, SL and SLK, whereby the floor group of one model is the same for all variations – sedan, caravan and hatchback, and the sidepanel supports have to be changed respectively. This is where the flexibility of Alufix comes into its own. The exchange of sidepanel supports is done with the help of quick connecting elements. It takes only a few minutes to adapt corresponding workpiece supports. During series production all variations are audited once per shift with the help of series measuring programmes. On the basis of a criteria catalogue this programme checks critical predetermined process data such as attachment of rear axle or attachment of the main floor.