Description of the test principle
Due to the high contact normal pressure as well as the high surface expansion rates which can be reached due to specifically designed die cavities, this test stand is very well suited to determine friction coefficients for massive forming operations. The application of the normal stresses and the measurement of the friction forces are conducted separately in the sliding compression test. After insertion of the test specimen, the specimen is compressed. Subsequently, after completing the compression, the plate is, as described schematically in the following figure, slid in relative motion against the specimen whilst the compression force is maintained. However, it is also possible to vary the compression force during the sliding cycle. Likewise, the sliding velocity can remain constant or be varied.
With the described sequence, it is thus possible to determine friction forces in dependence of different loading cases. By direct measurement of the friction forces during the sliding cycle, it is possible to determine the friction force in dependence of the sliding distance. Different tribological systems as well as tool and work piece materials can be investigated, therefore enabling a good reproduction of the occurring industrial conditions in cold forming operations.