Novel Powder Metallurgy Compacts with Internal Structures

A novel manufacturing technology was previously developed, with a utility patent applied for, which is capable of producing a hollow component in only two steps that is completely enclosed in metal. The technology leverages the powder metallurgy press-and-sinter technique to densify metal powder into a solid body completely encapsulating an internal structure. These internal structures most often are composed of a metallic shell containing a paraffin wax core. Firstly, metal powder is pressed ("compacted") around a solid metal shell containing a soft wax-filled core to form a metal compact or part containing an internal structure. Subsequent heating ("sintering") of the compact at particular conditions allows for the paraffin to melt out of the compact, thus producing a hollow metal part.Currently, the stress state of the body, shell, and core is unknown and shell mechanical failures often result from overly high compaction pressures. To address this, a finite element model will be developed which simulates the compaction of a metal, paraffin-core internal structure. The model will employ nonlinear material models for both the metal powder and wax core to allow for an accurate prediction of the powder densification. The model results will then compared against experimental density maps of internal structure compacts. Once validated, this model will become a valuable design tool as it is capable of predicting the stress in both the shell and core materials. Further work will focus on the fundamental understanding of how the internal structure disrupts the conventional compaction of the metal powder. By gaining this fundamental level of understanding, progress towards developing the technology into a commercial-ready product will be accelerated.