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Quality assurance in suspension development at BMW

In the premium car segment, Bavarian automobile manufacturer BMW is synonymous with innovation and driving pleasure. In living up to this claim, BMW attaches great importance to comprehensive quality assurance right from the development stage of vehicle suspension, beginning with the testing of individual suspension components such as helical compression springs. Relevant parameters include spring characteristic curves, distribution of resulting forces and intersection points.

BMW covers these testing requirements with an AllroundLine 20 kN testing machine from ZwickRoell of Ulm (Germany). This four-column, floor-standing testing machine features hard-chromed guide-columns and precision ball-screw with ball-nuts adjusted for zero backlash, guaranteeing high accuracy. AllroundLine also offers variable crosshead installation, giving the option of a second test area.

For use at BMW an additional upper fixed crosshead has been incorporated into the testing machine. A 6-channel measurement platform with mechanical overload protection is mounted on the lower fixed crosshead. To enable precise determination of upper intersection points, the moving crosshead is equipped with a 2-channel measurement platform. Measurement and control operations are handled by in-house ZwickRoell product testControl, allowing time-synchronous acquisition of measured values from all measurement channels at high resolution and measurement frequency, plus real-time processing. The measured values obtained provide information on quality-determining properties such as spring characteristic values and intersection points of resultant forces, together with transverse forces occurring in helical compression springs, delivering an important contribution to quality assurance.