Abstract

A necessity to distinguish between the influence of powder shape and size (particle size distribution) is especially demanding for highly filled metal powder feedstocks employed in additive manufacturing and powder injection molding. As their processability is evaluated through rheological behavior, the study focuses on the effect of powder size/shape on a wall slip, which is a typical phenomenon determining flow performance of these materials. Water and gas atomized 17-4PH stainless steel powders with D 50 of about 3 and 20 μm are admixed into a binder containing low-density polyethylene, ethylene vinyl acetate, and paraffin wax. Mooney analysis to intercept the slip velocity of 55 vol. % filled compounds reveals that wall slip effect appears to vary significantly with size and shape of metal powders-round shaped and large particles are the most prone to the wall slip. However, the evaluation is affected by the type of the flow streams resulting from the geometry of the dies-conical dies reduce the slip up to 60% in case of fine and round particles.

Highlights

  • A necessity to distinguish between the influence of powder shape and size is especially demanding for highly filled metal powder feedstocks employed in additive manufacturing and powder injection molding

  • Additive manufacturing is merging with powder injection molding (PIM) in the field of production of highly precise metal items and gaining relevant attraction due to a combination of processability of plastics and mechanical, electric or magnetic properties of metals,[1] there are still fundamental issues not answered satisfactorily

  • An entire manufacturing process consists of four steps of an equal importance, which lead to the final metallic items of tight tolerances and high quality.[2]

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Summary

Introduction

Additive manufacturing is merging with powder injection molding (PIM) in the field of production of highly precise metal items and gaining relevant attraction due to a combination of processability of plastics and mechanical, electric or magnetic properties of metals,[1] there are still fundamental issues not answered satisfactorily. As their processability is evaluated through rheological behavior, the study focuses on the effect of powder size/shape on a wall slip, which is a typical phenomenon determining flow performance of these materials.

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