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The accelerated growth of the industrial sector has resulted in the consumption of large amounts of non-renewable resources. Accordingly, this study evaluated the tribological behaviour of polymeric matrix composites the ultra-high molecular weight polyethylene incorporated with waste from the grinding process. The results obtained showed that these materials can be produced easily. The presence of the residue favoured an increase in the degree of crystallinity estimated at 32–45%, as well as the reduction of the friction coefficient. The tensile test showed that the presence of the metallic microparticles affects the behaviour mechanical of the composites. The micrographs evidenced the abrasion and adhesion wear mechanisms and the rolled-up wear particles phenomenon. On the other hand, the roughness affected the behaviour of the wear mechanisms in a nonlinear way. Therefore, this work showed the ease of obtaining environmentally friendly composites presenting a viable alternative to waste machining disposal. [ABSTRACT FROM AUTHOR]

The development of new cutting tool materials favors the hardened steel turning process, which has in some cases replaced the grinding process. Thus, this study evaluates the machined surface of hardened AISI 4340 steel via turning and grinding operations. The turning process evaluated the effects of the cutting tools (material, grade, and coating) and the process parameters (cutting speed and cooling condition). In the grinding process, the effects of the plunge rates and volumes of removed material Zw were evaluated. The machined surface was evaluated by amplitude roughness (Ra, Rt, Rp, and Rz), functional (Kp, Rk, Rpk, and Rvk), and statistical parameters (Rsk and Rku) and by the type and magnitude of induced residual stress (compression and tensile). In general, the turning process displayed the best results in the roughness parameters by promoting a better surface finish, mainly when the parts were machined at a cutting speed of 300 m/min. The increased cutting speed provided better surface integrity. The ceramic tool CC6050 presented the best performance, followed by the polycrystalline boron nitride (PCBN) and ceramic CC650 tools under cooling and dry cutting conditions. With respect to the residual stress, the grinding process induced compressive residual stresses in all tested conditions. On the other hand, turning-induced tensile stresses when using ceramic cutting tools (class CC650 and CC6050) and compressive stresses when using a PCBN cutting tool (class CB7115) were examined. In general, the use of cutting fluid in turning process did not provide a better performance in relation to the dry cutting condition. Based on the obtained results, the turning of hardened materials is a viable alternative to the grinding process. [ABSTRACT FROM AUTHOR]

Titanium and its alloys are associated with low density and excellent strength/weight ratio, biocompatibility in surgical implants, high mechanical strength at high temperatures and excellent corrosion resistance. The Ti6Al4V alloy is applied in the aerospace, biomedical, chemical, naval and petrochemical industries. However, these alloys present problems during machining and are therefore considered materials of difficult machinability at high cutting speeds. This paper aims to analyse the wear mechanisms in cutting tools using cemented carbide (H13A) and synthetic polycrystalline diamond (PCD) in the high-speed turning of Ti6Al4V alloy, under the following cooling conditions: dry, jet and minimum quantity lubricant (MQL). To measure wear, a microscope was used to measure flank wear in the tools. Next, the images of these tools were obtained using scanning electron microscopy for the identification of the wear mechanisms. According to the results, the variation in the cutting parameters (cutting speed and feed rate), type of tool material, as well as the cooling conditions significantly affects the behaviour of the wear mechanisms. The wear mechanisms presented in the cutting tools are not the result of one single mechanism, but a combination of many mechanisms. Overall, the primary type of wear is flank wear and the mechanisms are abrasion, adhesion and attrition (adherence and drag). [ABSTRACT FROM AUTHOR]

In the grinding process, high temperatures occur due to the removal of materials and the residual stresses that are generated on the machined surface, thus affecting the mechanical behaviour of the material. The performance of this process depends largely on conditions of cooling to prevent overheat of the parts, which can interfere in surface integrity of the pieces. Residual stress is a key factor that influences the reliability, precision and life useful of final products. As such, 3D parameters are important in tribological studies, with many of them showing a strong correlation with surface operational performance. Therefore, this work aims to study, through the 3D surface parameter and residual stress, the surface behaviour of AISI 4340 hardened steel after plunge grinding, while using different cutting fluids (mix—50% based mineral oil and 50% soybean oil; synthetic cutting fluid and integral fluid—mineral oil-based lubricant), as well as the use of minimum quantity lubricant (MQL) technique. All the residual stresses found for in the grinding samples under all cooling conditions were compressive stresses, which are beneficial to machined components. The synthetic fluid had lower compressive stresses. In relation to the 3D parameters, integral and mixing fluids also obtained a better performance because these fluids allowed greater lubrication in comparison to other fluids used. The results showed that the type of cutting fluid influenced the surface integrity of the ground pieces. It was concluded that the results showed the use of the mix and MQL fluids as an alternative to the use of the integral and synthetic cutting fluids, thus contributing to an ecologically correct and sustainable manufacture. [ABSTRACT FROM AUTHOR]