Net compaction pressure of metal powders

Conclusions

• 1. The following formula is proposed for calculating the net specific pressure σ_n in the compaction of powder materials:

  $$\sigma _n = \left( {1--- \frac{{16m\mu {\rm K}}}{{\pi d^3 \gamma }}} \right)\sigma ,$$

  where m is the compact weight,μ the coefficient of external friction, K the coefficient of lateral pressure, d the die-opening diameter,γ the density, andσ the specific compaction pressure.

• 2. Numerical values are given for the net specific pressure and net specific work of compaction in the pressing of iron, copper, aluminum, cobalt, nickel, and tin powders to various densities.

• 3. The net specific work of compaction is dependent on the size of the rubbing die surfaces and characterizes the compressibility of a given material at a given compaction velocity.

• 4. Values of compaction efficiency are quoted for various compact densities. For instance, at a porosity of 40%, compaction efficiency for all the metals investigated is about 85%.

• 5. It is demonstrated that, with increasing die diameter, compaction efficiency rises.