Determination of Angle of Repose for Powder Coatings by Angle of Repose Tester

1. Scope and description

As a collection of powders, powder coatings not only have free-flowing properties, but also have the properties of hindering flow and facilitating accumulation due to the friction between powder particles and their own gravity . When the free-flowing powder coating falls slowly from a high place and naturally accumulates into a cone on the horizontal plane , when it reaches a static state, the angle (that is, the angle of inclination) formed between the surface of the cone and the horizontal plane is called the angle of repose or the angle of repose. , Angle of repose. As shown in Figure 8-1-3.

The angle of repose is an important data reflecting the fluidity of dry powder. The angle of repose of a shell of electrostatic powder spraying is 35°~45°. When the angle of repose is below 40°, the dry powder has good fluidity and is easy to use. If it is greater than 45°, then The dry powder has poor fluidity.

2. Instruments and Materials

(1) Funnel: The mouth of the funnel should not be too large, preferably about 5mm; 

(2) funnel rack,

(3) Disc; 

(4) Protractor: including the shelf, the specific measuring device is shown in Figure 8-1-4.

3. Measurement method

Place the funnel frame and funnel according to Figure 8-1-4, make the funnel mouth align with the center of the powder receiving disc table, not too high from the disc, then pour the powder into the funnel, and then flow from the funnel to the powder receiving disc Pile up on the disc table until the disc table is full and overflow from the edge of the disc , and keep the θ angle at the maximum, and then measure the θ angle with a protractor. Repeat 3 times, and the average value is the angle of repose. If the accumulated powder is irregular in shape, it can be measured according to the two-point line at the vertex and the edge of the disc.