Pressing pressure P=P1+P2, side pressing coefficient =side pressureP2÷pressing pressure P=powder Poisson's coefficient u÷ (1-u) = tg2 (45º-natural sloping scaleΦ÷2).The bigger the side pressure is, the bigger the ejection pressure will be. The coefficient of cemented carbide powder is usually at 0.2-0.25. Pressing hard cemented mixture, pressing pressure is at 1200-1400kg/cm2, and side pressing only 1/3-1/4 to pressing pressure.

 

Indicate: Poisson's coefficient is the specific value of horizontal deflection and portrait deflection when material stretched or compressed in the pressing, and material will deform.

 

Pressure distribution in the pressing process: The mainly reason leading nonuniform pressure distribution is that friction among powder particle and friction between powder and die walls. The higher the height of the pressure is the more nonuniform the pressure distribution will be. Realize the double sides pressing or increase the compaction diameter can reduce the inhomogeneity of pressure distribution.

 

Unit compaction pressure=total pressing pressure/ produce compression area, for a hard cemented sample as an example:

Unit compaction pressure=P/ (20*6.5*1.22)

 

Indicate:

1)Unit is KN/mm2；

2) Shrink coefficient take 1.2 as an example, various powder take different shrink coefficient

3) Under normal conditions, shrink coefficient is dropping with pressing pressure, increase pressing weight can also decrease the shrink coefficient.