Powder Metallurgy - Powder Compaction

Powder Compaction

Powder compaction is the process of compacting metal powder in a die through the application of high pressures. Typically the tools are held in the vertical orientation with the punch tool forming the bottom of the cavity. The powder is then compacted into a shape and then ejected from the die cavity. In a number of these applications the parts may require very little additional work for their intended use; making for very cost efficient manufacturing.

The density of the compacted powder is directly proportional to the amount of pressure applied. Typical pressures range from 80 psi to 1000 psi, pressures from 1000 psi to 1,000,000 psi have been obtained. Pressure of 10 tons/in² to 50 tons/in² are commonly used for metal powder compaction. To attain the same compression ratio across a component with more than one level or height, it is necessary to work with multiple lower punches. A cylindrical workpiece is made by single-level tooling. A more complex shape can be made by the common multiple-level tooling.

Production rates of 15 to 30 parts per minutes are common.

There are four major classes of tool styles: single-action compaction, used for thin, flat components; opposed double-action with two punch motions, which accommodates thicker components; double-action with floating die; and double action withdrawal die. Double action classes give much better density distribution than single action. Tooling must be designed so that it will withstand the extreme pressure without deforming or bending. Tools must be made from materials that are polished and wear-resistant.

Better workpiece materials can be obtained by repressing and re-sintering. Here is a table of some of the obtainable properties.