High-speed steel drill life is found to be a strong function of the work material hardness (Tl α HB−16) when drilling cast iron. This strong dependence may account for the large variation in the life of the drills, which is observed in industrial conditions. Torque, thrust, and power are observed to be functions of drill wear. In the drilling of cast iron using H.S.S. drills of 10.32 mm (13/32 in.) dia at 690 rpm or 22.25 M/min (73 ft/min) maximum, the following relations were observed: torque(M)=0.125HBd2f+0.289HBd2r+0.0487HBd2w(3)thrust(T)=0.325HBdf+0.1242HBdw+0.755HBdr+0.0022HBd2(7) where HB = Brinell hardness of work material, d = diameter of the drill, f = feed per revolution, w = average flank wear, and r = radius at the cutting edge (0.01 mm or 0.0004 in.) all in consistent units. Flank wear of a drill increases rapidly at the end of its life. Torque and thrust reflect this change but are also influenced by workpiece hardness. Therefore, torque and thrust can be used as variables for drill wear sensing only when there is a close tolerance on the workpiece hardness, of the order of ±5 percent.

Grinding of ceramics is often treated as coarse grinding dominated by brittle fracture or fine grinding, at very low removal rates, dominated by plastic deformation. Through a set of experimental observations and analysis, it is shown that in grinding of ceramics the abrasive/work interaction can be treated similar to well known chip formation models. Such an approach permits the coexistence of ductile deformation and brittle fracture during the grinding of ceramics. When the grinding process is managed such that the brittle fracture is minimized, while maximizing the plastic deformation optimum results are achieved. In this regard it is conceivable to design ceramic grinding cycles, where the rough grinding cycle focuses on surface generation to achieve high material removal rate and productivity while minimizing brittle fracture and the finish grinding cycle focuses on surface generation which maximizes plastic deformation while still minimizing brittle fracture. While the above accounts for only one of four interactions in the grinding zone (viz) abrasive/work interaction, it is also necessary to address the other three interactions (viz) chip/bond, chip/work and bond/work interactions. The later considerations for ceramics grinding are identical to well established practices in metal grinding. When such grinding cycle optimization is carried out taking simultaneously into account the aspects of machine tool, grinding wheel, work material and operational factors, significant progress can be made in the grinding of ceramics. The results obtained through such systems approach are also described in this paper.

Duplex stainless steel with varying nitrogen contents of 0.22% (alloy 1) and 0.18% (alloy 2) were produced using a conventional induction furnace under normal ambient atmosphere. The samples were subsequently rolled under hot (1,000-1,100 C) conditions to various thickness reductions (15-75%). Both the hot rolled alloy samples were examined for the changes in microstructure and mechanical properties. The alloy 1 with higher nitrogen content opens out while deforming above 15%, whereas the alloy 2 deformation in the hot working zone is perfect without any defects. The crack initiation parameter for the alloy 1 is the secondary phase formation in the austenite area, which is brittle. The temperature range of 1,050 to 1,100 C is not desirable for hot rolling of alloy 1 and the same temperature range is suitable for hot rolling of alloy 2.

Tool life of the traditional cutting tools is comparatively lesser on machining the martensitic stainless steel AISI 416 which is one of the hardest materials. In order to increase the tool life, wear-resistant nanocoatings on the cutting tools have been explored. This study enunciates a comparison of tool life between PECVD (plasma-enhanced CVD multilayer nanocoated) and PVDMNC (PVD multilayer nanocoated) cutting tools on turning a martensitic stainless steel AISI 416 by experimental and theoretical investigations in addition to exploration of the machinability studies of cutting tool flank wear, tool hardness and surface roughness of work material. An orthogonal design, signal-to-noise ratio and Analysis of Variance (ANOVA) methods were employed to confirm the parameters like cutting speed, tool hardness and feed rate that are involved in the study to estimate the cutting toollife. The investigations confirmed that cutting speed was the most dominant factor in determining tool life while comparing with other parameters. It was observed from the ANOVA results that the cutting speed, tool hardness, and feed rate have contributed 41.44%, 33.79%, and 24.35% respectively in determining the tool life of PECVD cutting tools whereas the contributions of the same parameters were found to be 40.01%, 32.90%, and 26.63% respectively for PVDMNC cutting tool. It is evident from the results that the cutting performance of the PECVD cutting tool is superior in terms of cutting speed and hardness which were enhanced by 1.43% and 0.89% respectively in addition to lesser wear rate when compared to the performance of PVDMNC cutting tools. Nomenclature ANOVAAnalysis of variance F Feed rate (mm/min) CVD Chemical Vapor Deposition Process V Cutting speed (m/min) PVD Physical Vapor Deposition Process S/N ratio Signal-to-noise ratio PE Plasma Enhanced MS Means of squares DOC Depth of cut DF Degree of freedom F va The value of variance T Tool life HV Hardness value by Vickers

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