Abstract

The quality & properties of the final sintered product in Metal Injection Molding (MIM) is largely influenced by
the type of the powder & its properties such as particle shape, particle size distribution (PSD) packing density
and the powder-binder composition. The powder considered in the study is an iron powder of particle size d50 -
3 μ (Finer grade used in MIM industry) & d50 -45 μ (Coarser grade used in Powder metallurgy especially in
press & sinter applications). Here is an attempt to compare the properties of feedstock prepared with finer,
coarser, and a chosen combination of both to understand the advantages and dis-advantages of each powder
including its cost benefits. The chosen powder combination was mixed with a proprietary thermoplastic binder
system which acts as a matrix to hold the powder particles together. The highly loaded metal powder system
varying in powder particle size and shape with same binder matrix was mixed at predetermined ratio and
injection molded to tensile specimen to characterize metallurgical and mechanical properties. The molded
specimens were sintered in an inert atmosphere in a batch furnace. The experimental results indicate that the
finer particle size is beneficial in terms of the stability of the feedstock during injection molding, improving the
sintered density, deformation behavior and mechanical properties of the compact after sintering.