The relationship between the bulk material and the frequency of vibration best suited to stimulate that material is proportional to particle size. As a general rule, the smaller the particle, the better it responds to higher-vibration frequencies.
The relationship between amplitude of vibration and the bulk material is based on cohesive and adhesive forces. As the particle size increases, the amplitude required to cause the bulk material to move increases.
Particles that are fine and free flowing (low cohesive) tend to respond well to small amplitudes of vibration; free-flowing particles that are larger respond to larger amplitudes.
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