Utilization of rheological tests for determining of injection parameters of the compositions containing metal powders
Andrzej Skalski, Dionizy Biało, Ryszard Pilawka
Quarterly No. 2, 2010 pages 95-99
DOI:
keywords: viscosity, metal powders, injection molding, fillers, thermoplastic compositions, mixing
abstract This paper presents the results of investigation on the preparation of thermoplastic composition (mass) made of a special binder and fine-grained metal powders. Rheological tests of these materials is also presented. Such compositions are used to manufacture micro parts with dimensions in the tens or hundreds micrometers range for micro systems and micro devices. In this study iron and stainless steel powders with a granularity of 1, 4 and 16 μm were used. Components of the binders were wax, polyethylene and paraffin. Powders with binder were mixed in a blender-type 2Z at 125°C. During the mixing torque of mixing was recorded. The measurement of the torque was carried out up-to homogenisation of the masses. Based on the results maximum powders loading Vp of compositions was determined. During the tests loading of compositions by powders was in the range of 45 to 65% vol. The investigation of compositions viscosity were carried out on ARES rheometer with the measuring head arrangement in plate - plate system at constant shear rate and temperature of 100÷140°C. The study has shown that with increasing filling Vp increases the mixing torque and viscosity of the masses. The largest viscosity and mixing torque were obtained for the smallest grain powders of 1 μm. Moreover with increasing temperature decreases the viscosity of the composition. The authors attempted to find out how the viscosity affected the micro channel filling by the masses during injection. The test were carried out for selected micro channel with 0.077 mm2 cross-section. It was found that the reduction of viscosity strongly increases the length of the micro channel filling.