Effect of PCBN cutting tools wear on surface integrality in high-speed hard turning

In this paper, the effect of of flank wear polycrystalline cubic boron nitride （PCBN） tools on residual stresses, white layer and roughness of machined workpiece surfaces is studied. Experimental results indicate that with the increase of the tool wear, the surface of the machined workpiece tends to generate tensile residual stresses, and white layer becomes clearly thicker and uneven on the workpiece surface. The effect of the flank wear on the surface roughness is less within some range of flank wear value. The results show that it is possible to produce ideal surface integrality levels by controlling the tool flank wear.

Performance evaluation of minimum quantity lubrication by vege-table oil in terms of cutting force,cutting zone temperature,tool wear,job dimension and surface finish in turning AISI-1060 steel

In all machining processes, tool wear is a natural phenomenon and it leads to tool failure. The growing demands for high productivity of machining need use of high cutting velocity and feed rate. Such machining inherently produces high cutting temperature, which not only reduces tool life but also impairs the product quality. Metal cutting fluid changes the performance of machining operations because of their lubrication, cooling and chip flushing functions, but the use of cutting fluid has become more problematic in terms of both employee health and environmental pollution. The minimization of cutting fluid also leads to economical benefits by way of saving lubricant costs and workpiece/tool/machine cleaning cycle time. The concept of minimum quantity lubrication (MQL) has been suggested since a decade ago as a means of addressing the issues of environmental intru- siveness and occupational hazards associated with the airborne cutting fluid particles on factory shop floors. This paper deals with experimental investigation on the role of MQL by vegetable oil on cutting temperature, tool wear, surface roughness and dimen- sional deviation in turning AISI-1060 steel at industrial speed-feed combinations by uncoated carbide insert. The encouraging results include significant reduction in tool wear rate, dimensional inaccuracy and surface roughness by MQL mainly through reduction in the cutting zone temperature and favorable change in the chip-tool and work-tool interaction.

Feasibility Study on Cryogenic Milling of Carbon Fiber Reinforced Silicon Carbide Composites

Carbon fiber reinforced silicon carbide matrix(Cf/SiC)composites have the most potential application for high-temperature components of aerospace high-end equipment.However,high cutting temperature,rapid tool wear and severe surface damages are the main problems in dry cutting Cf/SiC composites process.The feasibility study on cryogenic milling of Cf/SiC composites using liquid nitrogen as coolant is investigated.Influences of milling parameters and coolant on temperature,cutting force,surface quality and tool wear are investigated,which is compared with dry cutting.Experimental results reveal that the cutting temperature in cryogenic milling of Cf/SiC composites is reduced by about 40%—60%compared with dry cutting.The milling force increases gradually with the increase of spindle speed,feed rate,depth and width of milling in cryogenic milling process.In addition,the machined surface quality in cryogenic milling is superior to that in dry cutting process.Fiber fracture,matrix damage and fiber matrix debonding are main material removal mechanisms.Flank face wear is the main wear form of the polycrystalline diamond(PCD)end mills.The tool life is prolonged in the cryogenic milling process because the reduced temperature inhibits the softening of Co binder and phase transition of diamond in the PCD end mills.