SIMULATION OF METAL-POWDER COMPACTION, FOR THE DEVELOPMENT OF A KNOWLEDGE-BASED POWDER-METALLURGY PROCESS ADVISER

The powder compaction simulations described in this paper have been pe rformed to demonstrate suitable modelling techniques for the developme nt of a knowledge-based system (KBS), capable of analysing proposed ge ometries of powder metallurgy (PM) compacts, (i.e. pre-sintered shapes formed from metal powders). The long-term aim is for the system to an alyse and if necessary modify, the geometry of the compact and then ge nerate process recommendations specifying settings for production para meters such as the required compaction pressures and punch geometries and motions. Following a review of the mechanisms of compaction, a met hod 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 app licability of such models is limited, because in practice friction bet ween 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 porou s metal plasticity compaction model. The relevant equations are solved using the ABAQUS(TM) proprietary FE package, in order to generate dat a relating the compaction pressure to the tool displacement for a PM c omponent. Experimental data has been generated through the uniaxial co mpaction of water-atomised bronze powder. Regression analysis was empl oyed to compare this data to the model output data, a close correlatio n 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 rea soning 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 fo rm one of the elements of a KBS for PM currently under development, to advise on the design and process technology for the production of com ponents by means of powder metallurgy. (C) 1998 Elsevier Science S.A. All rights reserved.