Warm compaction has the advantages of low cost, high density, high strength and so on, which makes its industrial application more and more extensive. The temperature and pressure are two important processing parameters for warm compaction.

 

Temperature

The maximum density can be obtained by using the process of warm compaction in a certain temperature range. While the factors that affect the range of temperature are the pressing force and the height of the powder. The greater the pressing force is and the higher the height of the powder is, the lower the optimum temperature and pressure temperature are.

 

 

With the height rises from 1. 0cm to 3. 8cm, the optimum temperature decreased from about 140℃ to 80~100℃. For a certain powder metallurgy part, the higher the height of the powder, the smaller the effective pressure is, and the height of the powder depends on the density of the loose assembly.

 

Pressure

When the temperature is different, the performance of the polymer is different, which makes the fluidity of the powder different. Therefore, for the alloy powder mixed with some kind of polymer, there is a temperature range with the maximum loosening density. Once over the temperature range, the powder filling behavior will deteriorate. If the temperature exceeds the optimum range of temperature, the pressing force will be too high, and the density will decrease, which is related to the increase of the springback after the powder metallurgy parts are out of the mold. 

 

The optimum temperature depends on the maximum compressibility of the powder and the minimum springback. From the point of view of lubrication, the greater the viscosity of the polymer, the stronger the bearing capacity of the film, and the better the lubrication effect. Of course, the viscosity of the general assembly leads to a decrease in effective pressure. When the polymer is at the glass temperature, the viscosity varies by several orders of magnitude. Therefore, the temperature and pressure temperature should be chosen near the vitrification temperature, and the temperature fluctuation should be strictly controlled.