The effect of powder characteristics on pressure sensitivity of powder injection moulding compounds

Abstract

A B S T R A C TPressure effect on the rheological behaviour of powder-polymer compounds intended for powder injection moulding was determined. A single-piston capillary rheometer modified by addition of a second chamber with a restricting needle valve generating backpressure increasing the pressure in the melted material during the flow through the die was employed to determine pressure sensitivity coefficients. The results obtained for three compounds varying in the characteristics of powders used confirmed that compounds at the loading level close to the maximum packing are more sensitive to pressure than polymer binder. It is shown that pressure sensitivity coefficients of these materials are strongly dependent on powder characteristicsparticle size and particle size distribution. The highest coefficient (32.9 GPa -1 ) was found for compound containing broad particle size distributed powder having a perceptible portion of small particles.

On the possibilities of merging additive manufacturing and powder injection molding in the production of metal parts

“…The changes in flow from a pseudoplastic to a dilatant indicate that particles could not form layers and slide over each other as shown, e.g. by Hausnerova (2011). During rheological tests on a 20/0.5 capillary, a binder separation accompanied by an accumulation of powder particles on the walls was observed for the PIM DMLS feedstock.…”

Effect of carbide powder characteristics on the PVT behavior of powder injection molding compounds

“…As we have shown recently [10][11][12] in the papers reporting pressure and temperature dependent flow properties of cemented carbide compounds, it is not only powder loading, but also powder particle size distribution and mean particle size influencing considerably a bulk compressibility of PIM compounds. Therefore, the aim of this research is to evaluate the influence of such powder parameters on pressurevolume-temperature behavior of PIM compounds.…”

An evaluation of the pressure-dependent melt viscosity of polyphenylsulfone

“…The detailed description of the experimental set-up can be found for example in Ref. 16. It should be noted that the comparison of Utracki's method, calculations from Bagley plots and measurements on a modified single piston rheometer provided by Goubert et al [17] and Pantani and Sorrentino [14,18] proved that the last mentioned approach is the most reliable.…”