The bulk density and the tap density of reduced iron powder.

What is bulk density and the tap density?

In powder compacting operations, often take filling capacity, which is filled with a certain volume of mold powder amount to control the density of presses and single heavy, this requires every time with the quality of the powder should be strictly the same cavity.
However, it is different for different manufacturers to fill a certain volume of iron powder. Therefore, it is stipulated that the volume property of powder is described by the density of loose packing or vibration density.
The density of loose packing is the powder quality in the unit volume of the powder under the specified conditions, and the unit is g/cm2.
The vibration density is packed in a vibrating vessel, and the powder density is measured after vibration.

The difference between the bulk density and the tap density.

Apparent density is accumulation of powder natural density, it depends on the resistance of the adhesion force, relative slide between particle and powder body the extent of the space is filled with small particles while typing or vibration can make the powder particles accumulate more closely (e.g., tap density), but there are still a lot of powder body hole which is called the pore volume of pore volume.
The ratio of pore volume to the apparent volume of powder is called porosity.
Therefore, the porosity of loose powder is higher than that of vibratory powder.