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.

This paper presents effect of the cavity position on green mass of metal injection (MIM) parts molded in a four-cavity split mold for different values of injection velocity, holding pressure profile and mold temperature. Test components where ring-shaped containing an external groove at the middle of height. It was found that the parameters that have greatest influence on part mass in single cavity are mold temperature folowed by holding pressure and injection velocity. Obtained experimental results also addres that the main source of variation in verticaly positioned runner system becomes cavity to cavity variation. In this case cavity to cavity variation increase is caused by separation and segregation supported by gravity effect.It was also found that in binder rich upper-cavity zone at sufficiently low mold temperature packing pressure increase cause decreasing of green part mass due to shift of glass transition temperature toward higher values.

Increased use and production of sintered stainless steel components require more intense investigation of their weldability. Weldability of P/M parts requires additional analysis compared to wrought or cast metals due to their specificities in physical properties. Residual porosity and sintering parameters of the heat resistant stainless steels are factors that mostly affect not only properties of sintered parts, but also their weldability. In this regard, effect of sintering parameters on the weldability of the Nb-modified heat resistant stainless steel HK 30 is discussed in this paper. Comparison of solid state and fusion welding of sintered components was performed using sinterjoining and plasma welding. Microstructure of sinter joined area, solidification structure of melting zone and microstructure changes in heat affected zone were explored using metallographic techniques. Hardness distribution through fusion zone and heat affected zone was also analysed and presented in the paper.

The success of air bending process depends on ability to accurately determine the punch displacement for desired bend angle after unloading. Punch displacement in the air bending is a complex function of tool and part geometry, mechanical properties of sheet and their changes during bending. The aim of this research was to develop the FE models for punch displacement and springback prediction using LS-Dyna. In order to validate results of the FE simulation, five bending experimets for materials S355MC and DD13 were conducted. It was found that FE springback predictions for microalloyed S355 MC steel are significantly lower compared to experimental data, while predictions for mild DD13 steel can be reliably used.

Metallurgical changes in weld nugget and heat affected zone (HAZ) during resistance spot welding of low carbon steel sheets is very important factor that determines final mechanical properties of welded joint. Thus, effect of spot welding parameters (current, welding time, holding time) on the mechanical and microstructural properties of weld nugget and heat affected zone were analysed in this work. Hardness was measured using Vickers method, while results were presented in the form of hardness distribution over a cross section of weld nugget and HAZ, for different welding parameters. It was observed that hardness in heat affected zone and melting zone is very dependent on welding parameters. Also, tensile tests showed that strength of the joint is very susceptible to welding parameters and thickness of the parent material. Microstructural changes in the weld nugget zone and heat affected zone were examined and analysed for some specific samples.

Influence of cooling fluid application on the tool wear, during longitudinal turning of hardened chrome nickel steel, on the basis of experimental investigations is presented in this paper. Cutting tool wear investigation through comparation dry machining and machining by cooling fluid application, for the same other machining conditions, are conducted. Tool wear size, tool wear shape and cutting tool life are taken into account by cutting tool wear investigation. Analysis of experimental results showed inverse proportion between coolig fluid application and flank wear size, as well as significance of influence on tool wear and its characteristics, via the flank wear shape. Also, analysis of experimental results showed significance of influence coolig fluid application on increase of cutting tool life.