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PurposeThis study aims to provide understanding of the influence of external factors, such as gravity, during sintering of three dimensional (3D)-printed parts in which the initial relative density and cohesion between the powder particles are lower compared with those present in the green parts produced by traditional powder technologies. A developed model is used to predict shrinkage and shape distortion of 3D-printed powder components at high sintering temperatures. Design/methodology/approachThree cylindrical shape connector geometries are designed, including horizontal and vertical tubes of different sizes. Several samples are manufactured by binder jetting to validate the model, and numerical results are compared with the measurements of the sintered shape. FindingsSimulations are consistent with empirical data, proving that the continuum theory of sintering can effectively predict sintering deformation in additively manufactured products. Originality/valueThis work includes the assessment of the accuracy and limits of a multiphysics continuum mechanics–based sintering model in predicting gravity-induced distortions in complex-shaped additively manufactured components. 

The prediction of microstructure evolution and densification behavior during the spark plasma sintering (SPS) process largely depends on accurate temperature regulation. A loop feedback control algorithm called proportional integral derivative (PID) control is a practical simulation tool, but its coefficients are often determined by an inefficient “trial and error” method. This paper is devoted to proposing a numerical method based on the principles of variable coefficients to construct an optimal linear PID controller in SPS electro-thermal simulations. Different types of temperature profiles were applied to evaluate the feasibility of the proposed method. Simulation results showed that, for temperature profiles conventionally used in SPS cycles, the PID output keeps pace with the desired profile. Characterized by an imperfect time delay and overshoot/undershoot, the constructed PID controller needs further advancement to provide a more satisfactory temperature regulation for non-continuous temperature profiles. The first step towards a numerical rule for the optimal PID controller design was undertaken in this work. It is expected to provide a valuable reference for the advanced electro-thermal modeling of SPS.