Powder injection moulding (PIM) is a multi-stage process to manufacture metallic or ceramic complex, functional parts in large quantities and with high material requirements. The flow in PIM filling process is a complicated non-isothermal problem with viscoelasticity effects and instabilities. The exact description of the whole process of the flow is very difficult. The existence of a yield stress on PIM-feedstock depends on particle interactions within the polymer matrix. Further factors, like powder loading and dispersion during the measurements, are influencing the rheological characterisation of PIM-feedstocks. Additionally, inertial and gravitational effects can have an influence for systems with a very low viscous matrix. Quantifying yield stress, however, must be done carefully because the value obtained depends on the analytical technique used. Knowing the flow behaviour of PIM-feedstock is necessary for successful filling simulation of PIM. In this context, the yield behaviour of a stainless steel feedstock was studied using a plate-plate controlled stress rheometer (CSS). The rheological data obtained from CSS were compared to the measurement made on a slit-die rheometer in controlled shear rate mode (CSR). Controlled stress rheology is more sensitive and provides more accurate results of yield stress than CSR.
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