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.

Laser cutting is a popular manufacturing process utilized to cut various types of materials. There are many non-linear interaction factors responsible for the performance of the laser cutting process. Identification of dominant factors that significantly affect cut quality is important. In this paper, the effect of the process parameters is analysed on the laser cut quality of an uncommon alloy, the tungsten alloy sheet with thickness of 1 mm. The experiments are conducted at three levels of the selected process parameters such as assist gas type (oxygen, air and nitrogen) and assist gas pressure. Taguchi design of experiments is used to obtain the optimum conditions through the study of signal to noise ratio for three quality characteristics such as kerf width, heat affected zone and surface roughness. Results of this study indicate that the optimal assist gas pressure is entirely different for kerf width, heat affected zone and surface roughness. The nitrogen as assist gas is suggested as the optimal assist gas for all of three quality characteristics.