Not all materials are suitable for automatic feeding machines. The conveyability of a material can be determined by measuring and analyzing certain characteristic parameters. The characteristic parameters of automatic feeding machines include: angle of repose, bulk density, particle factors, electrostatic constant, moisture sensitivity, explosion risk, toxicity, and corrosiveness.

(1) Angle of Repose
When evaluating the conveyability of a material, flowability is one of the most important parameters. It is typically represented by the angle of repose, which is the angle between the slope of the cone formed after the material is poured from a certain height and the horizontal plane. A smaller angle indicates better flowability, and vice versa. However, for certain special materials, the angle of repose may not accurately reflect flowability.

(2) Bulk Density
Bulk density refers to the weight per unit volume of a material in a loose state. Since particles or powders contain both material and air, bulk density can vary depending on the stacking method. Therefore, it is essential to measure the bulk density under actual conditions.

(3) Particle Factors
The weight, particle size distribution, shape, and hardness of particles are key factors that affect material flowability and the design of the conveying system.

(4) Moisture Sensitivity
All materials have hygroscopic properties. Materials sensitive to moisture may clump or agglomerate when they absorb moisture, altering their flowability. In severe cases, they may adhere to pipe walls or filter surfaces, leading to blockages in pipes or filters.

(5) Explosion Risk
When fine particles mix with air and reach a critical concentration, the presence of a spark may cause an explosion. Dust explosions require several necessary conditions: oxygen, critical concentration, and a spark. While the concentration of materials during conveyance in automatic feeding machines is difficult to control, oxygen and sparks can be managed. Using inert gas to isolate oxygen and eliminating static electricity to prevent sparks can help control the risk of explosion.