Maintaining component dimensions in metal injection molding (MIM) is difficult because of significant component shrinkage in the sintering step and shrinkage variation. Most of the shrinkage variation in MIM is due to density inhomogeneity in moldings (greens), induced in the injection molding step. Therefore, the focus of this research was to clarify the relationship between injection molding parameters and shrinkage of a ring-shaped component molded into a four-cavity split mold. Material used in research was Catamold 310N in the form of ready to mold granules. An experiment, according to a 2k factorial design, was performed to evaluate the effects of holding pressure profiling on shrinkage at different levels of coolant temperatures and fill rates. Results showed that the interaction of holding profile and coolant temperature has the most influence on the mean shrinkage. This finding offers a possibility to maintain the component dimensions in MIM by using the revealed interconnection between holding pressure profile and mean shrinkage.

Very important property of powder metallurgy parts is ability to join to components produced by different manufacturing technologies or dissimilar materials. Properties of powder metallurgy Nb modified HK30 components are highly influenced by conditions applied during sintering. Weldability of sintered components can be improved using favorable sintering conditions. In this regard, effect of sintering parameters on fusion weldability of Nb modified HK30 is presented in this paper. Investigation of weld joints between HK30, produced by different sintering conditions, and cast HK30 stainless steel is performed. In addition, examination of welds between sintered HK30 and wrought 304 stainless steel is also performed. Microstructural examination and hardness testing of fusion zones and heat affected zones were done for different combinations of base material.

Metal injection molding technology is commonly used in production of small and very complex parts. Residual porosity is unavoidable characteristic of P/M parts, affecting their final properties. During injection molding phase powder-binder separation can occur, causing green density variation through cross section of the part. This behaviour is particularly pronounced as complexity of the parts increases. As a consequence, zones with different density and residual porosity can be seen after sintering. In this regard, porosity and hardness distribution of the sintered ring-shaped part is analysed and presented in the paper.

The volumetric flow rate (injection velocity) and the holding pressure are metal injection molding (MIM) parameters that have a strong influence on the green parts density and density homogeneity, but their effect on sintered dimensions after sintering is still to a large extent unexplored. To reveal the relationship between the injection molding parameters and sintered dimensions, ring-shaped components were injection molded by using different values of injection velocities in combination with a rump-down and rumpup holding pressure profile. Afterwards, the green components were catalytically debound and sintered in the nitrogen (N2) atmosphere. Finally, the component dimensions: the height, inner and outer diameter were measured by using a coordinate measuring machine. The ready-to-mold granules Catamold 310N made of heat resistant stainless steel X40CrNiSi 25-20 (according to the EN standard) powder and polyacetal based binder were used. The results showed that the interaction between the injection velocity and the holding pressure profile can be used to systematically adjust shrinkage after sintering. This approach is based on the dependence of the binder crystallization temperature on pressure, when the powder/binder proportion changes with the injection velocity.

The weld line is an inevitable defect in the most injection molded components. It is a zone with reduced mechanical properties negatively influencing on the molding behavior in exploitation. The effect of: melt temperature, holding pressure and time, injection velocity and cooling time on the weld line tensile strength is analyzed in this paper. The material of the moldings was high density polyethylene (HDPE). The results showed that the holding pressure, injection velocity, melt temperature and cooling time have significant influence on tensile strength.