Simulation of metal powder compaction, for the development of a knowledge based powder metallurgy process advisor

Abstract

The powder compaction simulations described in this paper have been performed to demonstrate suitable modelling techniques for the development of a knowledge-based system (KBS), capable of analysing proposed geometries of powder metallurgy (PM) compacts, (i.e. pre-sintered shapes formed from metal powders). The long-term aim is for the system to analyse and if necessary modify, the geometry of the compact and then generate process recommendations specifying settings for production parameters such as the required compaction pressures and punch geometries and motions. Following a review of the mechanisms of compaction, a method is presented for quantifying the deformation of adjacent spherical particles, in order to estimate the volume change which would result from compaction of particular types of metal powders. However, the applicability of such models is limited, because in practice friction between the powder and the die wall reduces the pressure, producing a non-uniform density distribution in the compact. This effect is modelled through use of a finite-element (FE) simulation, which employs a porous metal plasticity compaction model. The relevant equations are solved using the ABAQUS™ proprietary FE package, in order to generate data relating the compaction pressure to the tool displacement for a PM component. Experimental data has been generated through the uniaxial compaction of water-atomised bronze powder. Regression analysis was employed to compare this data to the model output data, a close correlation being obtained. The long-term aim is to use FE techniques to develop a range of example cases for powder compaction. Such a case-based reasoning approach offers the potential for the proposed KBS to advise on the affects of variations in compaction parameters on the density and therefore the properties, of PM compacts. This work is intended to form one of the elements of a KBS for PM currently under development, to advise on the design and process technology for the production of components by means of powder metallurgy.