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In many applications in the metalworking industries, mass production of parts with holes possessing critical finish requirements for precision assembly operations demands tolerances in the working range of IT7 to IT5. However, this may not be achieved with regular twist drills, and further finishing processes such as reaming is normally required. To perform reaming, the workpiece needs to be previously drilled, so that two different cutting tools are needed and twice as much time is needed to machine compared with workpieces that need to be drilled, which in turn affects productivity and competitiveness. Therefore, any investment in the production of tools and techniques aiming to reduce the machining time of close tolerance holes, and lower tool wear rates and at a lower cost, will receive special attention from the machining sector. In this context, this paper presents technical and economic analyses of two manufacturing systems in drilling (drilling specially designed drill and regular drill with reamers) of compacted graphite iron (CGI) workpieces. The technical analysis was based on the tool wear mechanism, hole quality, and machining time, whereas the economic analysis was on total machining cost for use of specially designed drill and regular drills followed by reamers. Results showed lower wear on the specially designed drills compared with reamers. Also, the finish and dimensional deviations were similar to those obtained with reamers. Up to 40% of reduction in the machining time was achieved by using the specially designed drill, which resulted in a 57% reduction of the total cost. [ABSTRACT FROM AUTHOR]

Large quantities of coolant–lubricants are still widely used in the metal working industry, generating high consumption and discard costs and impacting the environment. This paper presents the evaluation of the performances of the various machining environments (dry, conventional wet and MQL technique) applied in hard turning of the AISI 4140 high-strength low alloy steel with coated mixed ceramic (CC6050) in terms of surface roughness, cutting force components, and tool wear. For this purpose, a number of machining experiments based on statistical four-factor (cutting speed, feed rate, depth of cut, and cutting radius) and hybrid-level factorial experiment designs uncompleted with a statistical analysis of variance were performed. The results indicate that the resulting cutting force obtained with the MQL machining process significantly improved when compared with other machining processes. For example: FRMQL ≈ 1.08 FRdry and FRwet ≈ 1.37 FRdry. Then, the RSM was utilized to define the optimal machining parameters. Finally, the ranges for best cutting conditions are proposed for serial industrial production. [ABSTRACT FROM AUTHOR]

In the beginning, metalworking fluids consisted of simple oils applied with brushes to lubricate and cool the machine tool. As cutting operations became more severe, metalworking fluid formulation became more complex. There are now several types of metalworking fluids in the market and the most common can be broadly categorized as cutting oils or water-miscible fluids. In this paper, attention is focused on recent research work on formulation and application of vegetable oil-based metalworking fluids in turning process. In addition, the performances of various vegetable oil-based metalworking fluids based on some process parameters such as thrust force, surface roughness, temperature developed at the tool chip interface, and tool wear during turning process using different tool materials were highlighted. [ABSTRACT FROM AUTHOR]