There are several types of powder compaction. At Dansk Sintermetal A/S we only use conventional powder compaction in fixed tools.
In the process the powder is placed in the powder holder at the top of the press, which can both be hydraulic or mechanical.
A specific amount of powder drops by gravity into the filling shoe, which distributes the powder in a hollow in the die.
Normally a pressure of 5-7 t/cm2 of projected surface area is applied across the pressure face, the powder is compacted between a set of upper and lower punches to a density of 85-90 % of the solid material. As the powder grains are extremely irregular in shape they lock into each other during compaction thus clinging together mechanically, while there is cold welding between the contact surfaces on the individual powder grains.
Thus the compressed grains form an imprint of the tool, a so-called "green component", which is then expelled from the tool and pushed away by the filling shoe while the next filling is taking place.
The green components are of a size and shape roughly similar to that of the finished component - though compensation is made for sintering shrinkage - and are strong enough to be handled and conveyed on to the next process, which is sintering.