When powders and granular materials are exposed to vibrational energy, the sample particles move relative to one another and fill in the air spaces between the particles. This causes the bulk density to increase. Materials being processed and shipped are exposed to vibration in many ways. Process equipment can vibrate as it moves or handles the material. Shipping methods like trucking or rail create vibrations in packaging.
Depending on the material, this packing of the particles can also increase the bonds between the particles and create strength in the powder mass. This increase in strength can be a problem as more energy will be required to initiate flow in the material after exposure to vibration. Many companies add flow agents to their materials to prevent increase in strength due to packing and pressure. However, these flow agents can make the increase in bulk density due to vibration more pronounced. In other words, powders that flow better will also flow better due to vibration and will pack more efficiently.
The REVOLUTION Powder Analyzer measure vibrational packing in three steps. First the material is prepared by aerating it in the sample drum for some time. Then the material is subjected to vibrational energy for a fixed time period. Finally the strength of the material in assessed by rotating the sample drum until the material breaks.
The EVOLUTION Powder Tester can also be used to test vibrational packing. With the EPT, the material is loaded into the test cell and exposed to vibrational energy with or without pressure on the material. The unconfined yield strength is then measured.
Link to instrument-specific test pages: