Powder Injection Molding of Metal and Ceramic Parts

Segregation measurement of powder injection molding feedstock using thermogravimetric analysis, pycnometer density and differential scanning calorimetry techniques

“…In the compaction method, the dry powder mixture is poured into a die, compacted by the application of pressure and then sintered to obtain the required final properties. In the powder injection molding method (PIM), a polymeric binder is used as a temporary vehicle for transportation of metallic or ceramic powder into a mold cavity and as a media supporting the powder particles until the final processing debinding-sintering steps [1,2]. The segregation of particulate materials is a well-known and generally unwanted phenomenon that occurs during processing, transportation and handling of powder or feedstock mixture [3,4].…”

“…Although the particles size distribution may stay unchanged after phase separation, this type of segregation leads to a change in volume fraction of powder from point-to-point in a feedstock. Regardless of the segregation process (segregation of particles and/or phase separation), fluctuation of the particle distribution in feedstock may lead to distortions, cracks, voids, warping and heterogeneous shrinkage of the sintered parts [1,2]. To evaluate the intensity of segregation from point-to-point on a component or from part-to-part on a batch of components, several methods are available including measurement of density, heat capacity, thermal conductivity, electrical conductivity, binder burnout, rheology or microscopic examination [17][18][19][20][21][22][23][24][25].…”

The influence of particle size distribution on the properties of metal-injection-moulded 17-4 PH stainless steel

“…There has been a limited amount of work on the effects of particle size and particle size distribution on the mouldability and sinterability of MIM powders. Most work available (Bricout et al, 2013;González-Gutiérrez, Stringari and Emri, 2012;Mannschatz, Muller and Moritz, 2011;Schwartzwalder, 1949) puts considerable emphasis on the influence of particle shape, tailored particle size distribution and powder loading on the flowability of MIM feedstock and hence the final mechanical properties of the sintered parts. Mamen et al ( 2015), however, studied the effect of particle size on the sintering behaviour of tungsten parts produced by MIM, but failed to report on the mechanical properties of their sintered parts.…”

Rheology of Highly Filled Polymers

“…Particular applications of highly filled polymers in the ceramic and metallurgy industries are ceramic injection molding (CIM), metal injection molding (MIM), and fused filament fabrication (FFF) [14,15]. FFF is a special variant of material extrusion (ME) additive manufacturing (AM).…”

“…In CIM, MIM, and FFF, a polymeric blend is used as a carrier or binder material for stiff powders during the fabrication of ceramic and metallic parts with complex geometry. Since the final part obtained at the end of these processes must be metal or ceramic, the filler content should be larger or equal to 50 vol% [15]. Measuring the rheological behavior of these materials is crucial to ensure that the correct processing conditions (e.g., for injection molding or extrusion) are used.…”