Our workplace, Technical University of Liberec, is currently engaged in research and production of cellular metal systems. Basically, cellular metal systems are materials with lower density. It is a research in the field of mechanical engineering that is focused on the development of new materials. In general, many methods have been developed for the production of cellular metal systems, e.g. by BANHART [2] or ASHBY [4]. At their production, the direct gassing of molten metals (mostly aluminium ones) or gassing by the powder agents (e.g. specially formulated aluminium powders) are mostly used. Depending on the manufacturing method, a cellular system with open or closed cells can be obtained. The most commonly used metal is aluminium and its alloys. We are currently focusing on the production of porous aluminium by using sodium chloride. Sodium chloride occupies regular sites in the aluminium material and thus contributes to the aluminium porosity. After solidification of the aluminium, sodium chloride is dissolved in water. Sodium chloride is relatively inert to the aluminium and together with it, has a favourable density (2160 kgm-3) compared to the aluminium density (2700 kgm-3). The values of these physical quantities were observed on the produced aluminium test specimens having  60 x 10 mm: relative density of porous system REL; porosity of metal system P; amount of solid phase system volume fraction VPM; density of porous metal system PM and porous material Young's modulus of elasticity EPM.

The effect of the computational model and mesh strategy on the springback prediction of the thin sandwich material made of micro-alloyed steel was investigated in this paper. To verify the chosen computational strategy, a comparison of the experimentally obtained specimen (U-bending) with the FEA result was performed. The Vegter yield criterion combined both with the isotropic and kinematic hardening law was used for the calculation. In addition, the effect of the deformation mesh element (surface and volume) on the accuracy of the springback prediction was investigated. It was concluded that the choice of the volume deformation mesh does not significantly improve the accuracy of the results. Moreover, it is quite a time-consuming approach. The much greater influence was monitored by concerning the selection of hardening law, where the anisotropic one was more suitable to be used on the springback prediction of a given sandwich material.

The paper deals the production of porous aluminum materials that are characterized by lower density and mechanical properties. Samples of porous aluminium materials were produced on the basis of the developed methodology that applied sodium chloride particles of different sizes (average size 4, 6 and 9 mm). The AlSi12 foundry alloy was preffered for the production of the aluminium porous material. As part of the experiments, samples of porous aluminium material in the shape of a truncated cone were made. The cavity of the foundry mould was in the shape of a truncated cone with diameters: D = 0.047 m, d = 0.040 m and height v = 0.040 m. The material properties were determined on the produced samples. Their weight, volume and their density, relative density were calculated. Based on empirical relations, their value of Young's modulus of elasticity and value of thermal conductivity were determined. The compressive strength of selected samples was monitored as well. The value of Young's modulus of elasticity was determined from the measured stress-strain course. Furthemore, the porosity of the produced samples was evaluated on a scanning microscope.

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Unconventional machining methods, or also progressive machining methods, such as laser cutting, waterjet cutting, ultrasound machining, etc. are undergoing a very rapid development. Laser cutting machines often evaluate even 80 parameters in real time. Their advantage is the significantly higher productivity. Many values are defined by the machine manufacturer and can not be changed for a given laser. For custom laser cutting there are 2 essential parameters, adjustable depending on the process gas employed. The aim of this article is to find the setting that will reduce the consumption of process media while maintaining or improving the quality of the machined surface.