<I>In-situ</I> Measurement of Non-uniform Sintering Shrinkage of Complex-shaped Powder Compacts

The metal powder injection molding (MIM) process enables extremely complex parts to be net-shape-molded. However, the need for producing complex-shape products with high dimensional accuracy brings about problems of dimensional accuracy and nonuniform deformation. To quantify the nonuniform deformation during sintering, and thus improve the dimensional accuracy, the measurement of two- and three-dimensional sintering shrinkage is required by all means. However, the conventional dilatometric measurement techniques enables only one-dimensional deformation in a simple shape specimen.The authors have developed an “in-situ monitoring system of sintering shrinkage” that uses digital image processing and enables the measurements of two- and three-dimensional changes during sintering on a non-contact and real time basis. In this paper, the nonuniform and anisotropic sintering shrinkage of two types of complex-shaped powder compacts prepared by metal injection molding was measured with MR-DICM (Multi-Reference Digital Image Correlation Method), which was an improvement of the digital image correlation method and newly developed for the computation of sintering shrinkage. The distribution of shrinkage in complex-shaped powder compacts of stainless steel (SUS304) was precisely determined from room temperature to 1543 K.