Experimental setup for long term high-precision static friction tests for clamping systems of rotary tables in cutting machine tools

The objective of the scientific investigation is the determination of the coefficient of static friction for clamping systems of rotary tables in cutting machine tools. New developments in this field of research are able to lead to an enhancement in tolerable cutting forces and machine accuracy or to the minimization of the required clamping forces and the constructed space too. In this context the requirement profile of the investigated clamping systems is more than complex. Since they have an immediate influence on the machine accuracy only smallest movements between the friction partners in the range of a few micrometres are tolerable. Furthermore a clamping system needs to withstand more than 100,000 clamping cycles and also braking applications in case of emergency. Against this background an experimental setup consisting of two testing benches was developed. The first testing bench offers the possibility of quick measurements of the coefficient of static friction by a linear movement to investigate a high number of different samples for a selection process. The second test bench in addition offers the possibility of testing the relevant samples by a torsional load for more than 100,000 clamping cycles and in braking applications. In a study the two test benches are validated and compared against each other based on a state of the art clamping system of a tempered steel on the basis of the determined coefficients of static friction. In addition the results of the long term friction experiments and the observed wear are discussed.