Experimental evaluations based on statistical and scientific criteria play fundamental role in identification of optimal performance parameters in manufacturing engineering. Based on this premise, the Doehlert's experimental planning method was applied to external cylindrical turning process of ABNT 1045 steel, with the purpose of determining the roughness correlation as a function of the cutting speed (Vc) and feed rate (f). The Doehlert's matrix was defined with five levels for feed rate and three levels for cutting speed, according to coded variables. From these experiments the correlation between input and output variables was determined. The best model is in agreement with the analysis of variance and Fischer's test. Graphs were obtained for both response and contour surfaces. In addition, the optimal point for the best model was determined by the Lagrange criterion, which corresponds to a feed rate (f) of 0.0880 mm rev-1 and the cutting speed (Vc) of 155 mm min.-1 , resulting in a minimum roughness average value (Ra) equals to 0.8916 μm.

In industrial casting operations, the possibility of implantation of a diversity of operational conditions has as consequence the generation of a wide range of solidification structures, affecting the mechanical properties and the quality of the final product. Due to the importance of the study of thin slabs solidification, for this work is used a system that allows the physical simulation of initial stages of continuous casting of thin slabs for laboratory experiments under several solidification conditions. Experiments were carried out using Pb-2.5% Sb alloy that presents low melting temperature and characteristic structure. For the Pb-2.5% Sb alloy thin slabs were obtained in cooled mold without reduction and with 10 and 20 mm reductions. It was found that the degree of deformation applied tends to increase the equiaxed region by the breakage of the dendrites as well as the possibility of the formation of equiaxed dendritic structures. It was observed that the deformation of this alloy directly influences the secondary dendrite spacing, tending to decrease it.

Experimental evaluations based on statistical and scientific criteria play fundamental role in identification of optimal performance parameters in manufacturing engineering. Based on this premise, the Doehlert's experimental planning method was applied to external cylindrical turning process of ABNT 1045 steel, with the purpose of determining the roughness correlation as a function of the cutting speed (Vc) and feed rate (f). The Doehlert's matrix was defined with five levels for feed rate and three levels for cutting speed, according to coded variables. From these experiments the correlation between input and output variables was determined. The best model is in agreement with the analysis of variance and Fischer's test. Graphs were obtained for both response and contour surfaces. In addition, the optimal point for the best model was determined by the Lagrange criterion, which corresponds to a feed rate (f) of 0.0880 mm rev-1 and the cutting speed (Vc) of 155 mm min.-1 , resulting in a minimum roughness average value (Ra) equals to 0.8916 μm.