A validation procedure for numerical models of polytetrafluoroethylene (PTFE) powder pressing

Abstract

The proposal of this research project is to develop an experimental procedure for the validation of numerical models during polytetrafluoroethylene (PTFE) pressing. These Finite-Element models are applied during the simulation of the compaction stage of PTFE, which strongly influences the mechanical properties of the final compacted part. Besides, this simulation has extreme importance for the tool project, process optimization and reduction of production cost. However, the satisfactory simulation is not trivial to perform due to the high complexity and precision required, because the granules of material are under a complex loading path during the compaction step of the part. Thus, two validation procedures are proposed. The former was developed by the group of research, until now, in ceramic materials, which is divided into two stages: uniaxial pressing followed by isostatic pressing. The latter will be developed during the present project and consists of pressing the granular material uniaxially, measuring the circumferential strain on the die-wall external surface. The validation procedure is performed by the comparison of experimental parameters obtained from tests - reaction force in the actuator, displacement of the actuator, normal stress in the sensors arranged radially, tool deformation and the final geometry of the piece - with results from the numerical simulation by the finite-element method. Thus, one can expect that the validation procedures demand robustness of the numerical model so it can represent the proposed experiments, making possible its future application in industrial processes.