Fließversuche

Fließversuche are experimental procedures used to characterize how a material flows under defined conditions. They aim to quantify flow behavior, such as viscosity, yield characteristics, and workability, for liquids, pastes, suspensions, and sometimes powders. The tests can be gravity-driven or pressure-driven and are performed with standardized geometries or setups to enable material comparisons.

Typical methods include capillary flow tests, where material passes through a small die to yield a flow rate or pressure-driven measurements in rheometers with cone-plate or parallel-plate geometries to determine shear viscosity and yield stress. Non-instrumented or simpler field tests, such as slump tests, flow table tests, or Bostwick measurements, are also used in concrete, pastes, and sauces to assess flowability and consistency. For polymers, melt flow rate tests are a common form of Fließversuch, carried out at a specified temperature and load to obtain an apparent melt flow index. In glass and ceramics, capillary or gravity flow tests help assess viscous flow of melts at operating temperatures.

Applications span several industries. In polymer processing, Fließversuche inform extrusion and molding by providing melt viscosity data. In construction, they evaluate the workability of fresh concrete or cementitious slurries. In food and pharmaceutical industries, they help characterize texture and ease of processing. In powder technology, flow behavior influences handling and compaction. Results are sensitive to temperature, pressure, moisture, particle size, and surface interactions, so standardized conditions are essential for meaningful comparisons. The term is widely used in German-speaking contexts to describe these flow-characterization experiments.