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The study of machining nickel-based superalloys has assisted in developing new techniques associated with cutting processes and tools. Hastelloy Ò X offers ideal properties for engine manufacturing in the aerospace and aeronautical applications that require high surface qualities. Thus, this work investigates the effects of three input parameters (cutting speed, depth of cut, and lubricooling conditions) at three levels on the average roughness values in the finish turning using a PVD-coated carbide tool. The 0.1 mm/rev feed rate was kept fixed, and the parameters were combined, randomized, and optimized by the Box-Behnken Design of Experiment. The statistical results showed that the most significant input parameters were cutting speed and depth of cut and their respective interactions. Furthermore, the cutting conditions with lower cutting speed and depth of cut above 1.5x tool nose radius generated high roughness values due to chatter vibration. After optimization, the best average roughness value obtained was below 0.8 mm, with a 400% increase in the material removal rate.

Dissimilar Al-Cu joints are desirable due to the combination of the good electrical and thermal properties of copper with the economic advantages of aluminium. However, different chemical, mechanical and thermal properties turn dissimilar welding into a challenge with traditional fusion welding techniques. Friction stir welding appears to be a good alternative to welding dissimilar materials. Most of the works in Al-Cu FSW have been performed with Al on top. This work investigates the influence of heat input on the shear strength of aluminium-copper lap joints produced by FSW with a copper over aluminium lap configuration. Welds produced with the ω/ν rate of 200 rev.mm -1 or 500 rev.mm -1 resulted in the melting of the base materials and material leaking. Joints with shear tensile strength varying from 76 to 85% of the original resistance of AA6060 T5 were produced when the ω/ν rate was varied from 80 to 110 rev.mm -1 . The fracture was governed by tension overload on the aluminium sheet, resulting in little influence of welding defects, such as tunnelling, on the joint strength.

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Friction stir welding (FSW) is a solid state welding process that has been studied for dissimilar welding applications, especially aluminum and copper. However, the quality of dissimilar Al/Cu FSW joints is often impaired due to the formation of intermetallic compounds (IMCs), which affect both mechanical and electrical properties. This paper investigates the feasibility of FSW in producing dissimilar Al/Cu lap joints were copper is positioned over aluminum. In order to access the influence of rotational speed over the resulting joint, four different rotational speeds were tested for the same welding speed. The produced joints were then evaluated in terms of weld appearance, defects and the electrical resistance of the welded joints. Visual and ultrasound inspection indicated no discontinuity in any of the produced samples. Electrical resistance results indicate no influence of rotational speed. Moreover, electrical resistance of the Al/Cu FSW lap joints were smaller than the average between the electrical resistances of single metal joints welded with the tested materials in similar conditions. The experiments indicate that is possible to produce sound Al/Cu lap welds for the parameter window used, including the positioning of copper over aluminum, that is discouraged by literature. The small values of electrical resistance indicate no deleterious effect of IMCs over this characteristic.

The aim of this work is to analyze the tool wear effects on surface finish of machined components. Long-term machinability tests were performed for ASTM 1040 and 1045 carbon steels with carbide tools, in which tool wear and surface roughness were periodically evaluated. Surface finish was analyzed as a function of processed material and cutting speed with new machining tool, and a significant influence was found for cutting speed at a confidence interval of 10%. When evaluated as a function of time and tool wear, surface roughness showed an exponential relationship with both variables. However, a high dispersion occurs close to the end of tool life, especially for AISI 1040 steel. Weak influence of cutting speed (for the range of speeds tested) was observed on the relationship between tool wear and surface finish, indicating that a single equation can describe its behavior for all studied conditions. The relationship between the surface roughness and the cutting time was found to be stronger for the ABNT 1040 steel.

The understanding of machining processes comprises the study of phenomena such as: chip formation, cutting forces, tool wear mechanisms and the influence of the cutting parameters and machined materials on them. The aim of this work is to analyze the tool wear effects on machining forces during machining of AISI 1040 and 1045 carbon steels with carbide tool. Long-term machinability tests were performed, in which cutting force, feed force and tool wear were measured. Tool life results were analyzed, with best tool lives found for the AISI 1040 steel for all tested speeds. The other variables were analyzed as function of both time and tool wear. On the time domain, strong dependencies were found for both materials for tool wear, cutting force and feed force. The relationship between cutting force and tool wear showed good correlation for both materials, and the same was observed for feed force and tool wear relationship. Weak influence of cutting speed was observed on the relationship between tool wear and machining forces, which suggest that a single equation can describe them for all studied conditions with reasonable accuracy. The regression results are able to predict cutting forces as a function of tool wear with an average error of about 2.6 % during machining of AISI 1040 and 5.2 % for AISI 1045 steel. For the prediction of feed force as a function of tool wear, the average error is about 5.6 % for AISI 1040 and 7.0 % for the AISI 1045 steel, since a restricted domain is established. Data analysis showed a discontinuity in the behavior of feed force as a function of tool wear near the end of the life of the tools for most tests performed with AISI 1045 and some tests with AISI 1040 that suggest backwall wear, which was further evidenced by sudden change of chip form near the end of tool life in AISI 1040 steel.