Full definition
Maximum angle that the free surface of a piled granular material forms with the horizontal before it slides. Typical values: dry sand 30°, iron ore 35-40°, coal 38°, clinker 40°. Determines the load cross-sectional area (surcharge angle) and maximum allowable conveyor inclination, generally limited to 2/3 of the angle of repose. Fundamental parameter in capacity calculation per CEMA and DIN 22101. Measured in the laboratory using a tilting-table method.