The angle between the horizontal and the sloping surface of a powder pile formed under defined conditions.
Also called: repose angle; powder pile angle.
How do you calculate angle of repose from a powder cone?
For a conical pile, use its vertical height and horizontal base radius. The angle is measured from the horizontal, not from the vertical. Height and radius must use the same length unit, and the inverse tangent must be expressed in degrees if the result is reported in degrees.
In a platform-based calculation, the radius may be fixed by the apparatus. A 100 mm diameter platform has a 50 mm radius, for example; use the radius appropriate to the actual geometry.
Angle θ = arctan(h / r), where h is pile height and r is base radius
Comparing angle-of-repose measurements
Only after checking how the piles were formed and measured. Keep the apparatus geometry, pile-forming method, sample preparation and material condition with the result. Comparing an angle from a defined platform with an angle from an unspecified heap leaves the measurement basis unclear.
Powder state also matters: settling, consolidation and aeration describe different conditions. An angle is one observation of the resulting pile, not a complete account of powder behaviour under every stress or feeding condition.
Does a smaller angle prove that a powder will fill better?
It describes a shallower pile for the stated measurement. That alone does not establish stable discharge, packing or capsule fill-weight variation. An angle test and a density-derived index observe different things, so their numerical scales are not interchangeable.