Honza, E.

Klein, A.

Mueller, T.

Piotter, V.

Plewa, K.

English

KITopen

KIT – Universität des Landes Baden-Württemberg undnationales Forschungszentrum in der Helmholtz-GemeinschaftCONSIDERATIONS ON THE PRODUCTIONOF MICRO AND PRECISION PIM PARTSV. Piotter, E. Honza, A. Klein, T. Mueller, K. PlewaKarlsruhe Institute of Technology (KIT)Institute for Applied Materials – (IAM-WPT)Hermann-von-Helmholtz-Platz 1D-76344 Eggenstein-Leopoldshafenvolker.piotter@kit.eduAcknowledgements This work was carried out with the support of the Karlsruhe Nano Micro Facility (KNMF, www.knmf.kit.edu), a Helmholtz Research Infrastructure at Karlsruhe Institute of Technology.Further thanks go to external institutions, especially the DFG, and all supporting colleagues at KIT.Influence of powder loadingAn important influencing factor in powder injection moulding effecting considerably the applicability of the whole manufacturing techniqueis the achievable part precision after sintering.To investigate interactions of parameters and influences of process conduct a research tool with two movable pistons had been build.One result was that the powder loading showed a positive effect on accuracy up to about 68Vol% for a typical 17-4 PH feedstock.Crossing this boarder influence became detrimental.Further trials showed that subsequent compression by piston movement led to significantly smaller membrane thicknesses compared tocavity filling by injection only.Parts with thickness variation To investigate filling behaviour and dimensional accuracies a new samples design had been created: A massive cylindrical ring with a thin membrane onthe top. The challenge was to produce membranes as thin as possible and investigate the square sections and reproducibility of thickness profiles. Thepistons enabled a subsequent compression of the feedstock in the membrane cavity and a defined adjustment of the membrane thickness.The process conduct had been defined like that:• Pull back the piston to provide a relatively wide membrane cavity• Fill this cavity by injection of feedstock• Push the piston forward up to the final small membrane thicknessResults of the first trials showed that:• Membrane filling only by injection is possible down to thicknesses of ca. 400µm• Using the injection+compression process smallest membrane thicknessesreached so far are in the range of 250µm after sintering. For these trials a simple cylinder geometry which can beregarded as a quasi full material sample had been chosen.As feedstocks different formulations containing 60Vol% to70Vol% 17-4PH steel powder (d50 ca. 4µm) mixed with a typicalMicroPIM binder system had been used.cylindrical sample, Ø = 2.015mmExperiments revealed that best accuracies can be reached if the injectedfeedstock pushes back the piston in a quasi balanced force state.To investigate influence of the powder loading the mean diameters and standarddeviations had been determined as a function of the powder content: Diametersincreased whereas S.D. decreases. If powder loading approaches 70Vol%accuracy drops down. i.e. a critical filler content has been reached here.schematic drawing of twin-piston toolmeasuring positions

Considerations on the production of micro and precision PIM parts

https://publikationen.bibliothek.kit.edu/220096982/3816599

Considerations on the production of micro and precision PIM parts

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