Nowadays, there are growing demands on the accuracy of production. Most of this is reflected in precise manufacturing, such as the investment casting process. Foundries are looking for causes of defects in some cases for a very long time, and it may happen that the source of defects is completely different from what was originally assumed. During the casting process there exist potential causes of defects as oxygen inclusions. This paper represents a summary of the beginnings of a wider research that will address the problems of gating systems in investment casting technology. In general, the influence of the melt flow is underestimated and the aim of the whole scientific research is to demonstrate the significant influence of laminar or turbulent flow on the resulting casting quality. Specifically, the paper deals with the analysis of the most frequent types of defects found in castings made of expensive types of materials casted in an open atmosphere and demonstration of connection with the design of gating systems in the future.

Currently, due to the economic and ecological aspects, light alloys are increasingly important construction material, in particular in the transport industry. One of the popular foundry magnesium alloys is the alloy AZ91, which among others due to mechanical properties and technological features, is used, for example, for light structural parts.
The paper presents the results of research on modification of the AZ91 alloy surface layer in the plasma electrolytic oxidation process. The change of usable properties of the produced coatings was obtained by introducing additions of silicon carbide or boron nitride. The thickness and hardness of the protective layers produced, resistance to scratches and corrosion resistance were determined. Moreover, the friction coefficient of the coating-steel pair was investigated. The quality of the connections made between the coating and the substrate, i.e. the magnesium alloy, was also evaluated. The results obtained for coatings with silicon carbide or boron nitride additives were always compared to the results obtained for unmodified samples.
On the basis of the obtained results, it was shown that the introduction of boron nitride additive to the AZ91 alloy coating produced in the plasma electrolytic oxidation process significantly improves the resistance to: (i) corrosion and (ii) abrasive wear of the coating.

Innovative procedure of microalloying continuous cast aluminum strip, thickness 10 mm, by Be, Zr and Mn using 3C Pechiney technology (no. 39762, P-377/76), and modifying the existing parameters for strip casting and crystallization was implemented under industrial conditions with two randomly selected batches 2×8 tones, without previous selection of standardized quality of aluminum, purity Al 99.5%, obtained by electrolysis. The application of microalloying and overall structural modification of the technology resulted in obtaining nanoscale, ultra-thin, compact oxide high-gloss film with uniform surface of continuous cast strip, instead of the usual thick and porous oxide film. The outcome of microalloying the obtained equiaxed fine-grained nano/micro structure was avoiding anisotropic and dendritic microstructure of the strip, and improving deformation and plastic properties of modified continuous cast strip subjected to the technology of plastic treatment by rolling until the desired foil thickness of 9 μm was obtained. The invention of microalloying and structural modification, including multiplying effect of several components, directly or indirectly, changed numerous structurally-sensitive properties. The obtained nano/micro structure of crystal grains with equiaxed structure resulted in the synergy of undesirable <111> and inevitable <100> and <110> textures. Numerous properties were significantly enhanced: elastic modulus was improved, and intensive presence of cracks in warm forming condition was prevented due to rapid increase of the number of grains to 10000 grains/cm2 in as-cast state.