Angle of Repose or Poured Angle
- It is a parameter usually used for the calculation of interparticle force that affects mostly powder mobility.
- The simplest and easiest method for the calculation of the (θ) is the “poured” angle.
- A funnel with a wide outlet is attached at a distance of 10 cm above the bench, where a piece of paper is placed directly below the funnel.
- The powder is poured onto the funnel when it is locked. The powder flow through and gather on the paper. The diameter of the cone (D) and two opposite sides (L1 + L2) are measured with rulers.
- It is calculated from the equation
Angle of repose (θ) =
arc cos [D/(L1 + L2)] or tan-1(2h/d)
- The connection between flow properties and angle of repose has been established.
Limits:
The angle of repose (θ) is Less than 25° = Excellent Flow
If it is More than 40° = Poor Flow
Conclusion:
| The angle of repose (θ) | Flowability |
| Less than 25° | Excellent |
| 25 to 33° | Good |
| 30 to 40° | Passable |
| More than 40° | Very Poor |
| 56-65° | Very Poor Flow / Very Cohesive |
| > 66° | Approximatively no flow |
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Reference:
https://link.springer.com/10.1007/978-3-319-73568-9_15
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