Abstract: CBN-WC-10Co fibers with macroscopic dimensions of 0.8 mm×0.8 mm×6 mm are fabricated by using spark plasma sintering technique and wire electro-discharge machining. The rake surface and flank surface of the fibers are polished to form a zero rake angle and a 20&$176; clearance angle by using diamond abrasive paper of 3 μm in mesh size. The fibers can be orderly arranged and be prepared oriented fiber cutter through replacing the abrasives in a grinding wheel. A comparative investigation is carried out on the machining mechanisms of TC4 titanium alloy by single cBN-WC-10Co fiber and by single CBN grit. It is found that both cutting force ratio (F_n/F_t) and specific cutting energy of cBN-WC-10Co fiber are decreased, and cutting quality is comparable to that for CBN grit. Single cBN-WC-10Co fiber cuts workpiece with zero rake angle during cutting and the flanks of the fiber are perpendicular to the machining surface. Therefore, the volume of workpiece material flowed to the front and flank of the fiber is small because of smaller squeezing action, and then only a little material accumulate on the sides and the outlet end of the cutting scratch of single cBN-WC-10Co fiber. The material removal rate along the cutting direction of the scratch formed by the cBN-WC-10Co fiber is 98.1%~99.1% and the pile up ratio is 0.9%-1.9%. However, the material removal rate and the pile up ratio of the scratch cut by the CBN grit are -54%-86% and 10%-160%, respectively. This indicates that the cBN-WC-10Co fiber has excellent material removal performance in comparison with the CBN grit, and the high machining efficiency can be achieved by increasing cutting parameters.

Key words: CBN-WC-10Co, cutting force, cutting performance, material removal rate, scratch topography, single fiber cutting