Experimental study of the deformation behaviour of compacted metal powders used in a new rapid tooling process

To examine the feasibility of a newly proposed rapid tooling process based on the backing of a metal shell with metal powders, the compressive deformation behaviour of selected metal powders and metal shells was investigated. It was found that the mechanical properties of the powder material and the mixing ratio of powders of different sizes had a significant effect on the compressive deformation behaviour of the compacted powders. Softer metal powders with the same compressive stress tended to produce greater plastic deformation and formed a block under a stress of 138 MPa. Mixing two or more powders of different sizes could significantly increase the deformation resistance of the compacted powders. Minimum plastic deformation was achieved when the fraction of the coarse powder in a binary powder mixture reached 0.77. Initial loading at a higher stress could minimize or eliminate the plastic deformation in subsequent loading cycles. This feature could be used advantageously in powder packing for the proposed new rapid tooling process. Some elastic properties of the compacted metal powders were also determined from the compression experimental data.