There are several fundamental steps for the technological preparation, which are required to optimize the thermal spray coatings. In order to ensure proper bonding of the coating, important is properly preparation of substrate. The surface of the substrate has to be clean and should have a suitable roughness after previously performed treatment. Knowledge about the effects of process parameters allows designing the coatings obtained with an optimal adherence. Only when all the components of the spraying coating process are used correctly there is possible properly design the technology. The article describes the impact of technological parameters of grit blasting to obtain the roughness of the steel substrate (steel S185) to the process of metallic coatings by cold gas dynamic spraying. Research was carried out by using the Dymet ® 412K appliance, designed for applying metal coatings and substrate surface cleaning. Grit blasting is a mechanical method of surface preparation of metal parts. It allows obtaining a high degree of surface cleanliness and a determined roughness. The authors took into account parameters such as operational pressure, spray angle (incidence) of abrasive grit blasting in the axis of the stream and feed rate of used abrasive particles (Al2O3) passed to the nozzle of spray gun. Carried out the multiple regression analysis of the roughness parameters results. It revealed the existence of certain influences and changes of process parameters, which affect on the surface quality. Carried out calculations by using a multiple regression showed that the greatest correlation is between the required roughness and the feed rate of used abrasive particles. The studied roughness was described by the parameters: Ra, Rz, Rt and RSm. Stepped growth (from 0.1 to 0.8 g/s) of abrasive particles feed rate caused a decline of all of the roughness parameters. It has been found that the values of the roughness in the least depend on the operational pressure.

Surface engineering is important for carried out to improve the quality of the surface layer of the material. It is important that in special applications of corrosion resistant steel, low surface roughness is obtained. Duplex stainless steel is becoming more widely used for example in the petrochemical industry or shipbuilding. Duplex stainless steel is a material classified as difficult-to-cut. It is therefore important to investigate the impact of machining parameters on the durability and wear of a cutting tool. In the paper has determined the influence of variables machining: feed rate, depth of cut, cutting speed, on the maximum tool flank wear. Surface machining was carry out with carbide tipped inserts. The criterion of the smallest roughness and the highest wear was proposed.