Abstract

Low-pressure powder injection molding (LPIM) is a cost-effective technology for producing intricate small metal parts at high, medium, and low production volumes in applications which, to date, have involved ceramics or spherical metal powders. Since the use of irregular metal powders represents a promising way to reduce overall production costs, this study aims to investigate the potential of manufacturing powder injection molded parts from irregular commercial iron powders using the LPIM approach. To this end, a low viscosity feedstock was injected into a rectangular mold cavity, thermally wick-debound using three different pre-sintering temperatures, and finally sintered using an identical sintering cycle. During debinding, an increase in pre-sintering temperature from 600 to 850 °C decreased the number of fine particles. This decreased the sintered density from 6.2 to 5.1 g/cm3, increased the average pore size from 9 to 14 μm, and decreased pore circularity from 67 to 59%.

Highlights

  • Powder injection molding (PIM) has been emerging as an alternative technology to conventional powder metallurgy thanks to its numerous strong points, such as high shape complexity and productivity, good precision, and adequate surface quality [1,2,3]

  • In ceramic injection molding (CIM) or metal injection molding (MIM), ceramic or metallic powders are mixed with a polymeric binder to form molten feedstocks that are injected into a mold cavity at a given injection pressure

  • The low viscosity (

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Summary

Introduction

Powder injection molding (PIM) has been emerging as an alternative technology to conventional powder metallurgy thanks to its numerous strong points, such as high shape complexity and productivity, good precision, and adequate surface quality [1,2,3]. Each processing stage is important, powder-binder formulation and binder removal are critical steps driving the PIM parts’ final chemical composition and mechanical properties [6,7]. In conventional high-pressure powder injection molding (HPIM), the binder, which consists of a blend of low- and high-molecular-weight polymers ( called primary and secondary binders, respectively), is removed in two steps. During the MIM process, several chemical reactions such as oxidation, reduction, carburization, and decarburization may occur during debinding and sintering, affecting the parts’ magnetic, electric, physical, and mechanical properties

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