Evaluation of the thermal characteristics in high-speed ball-end milling

In this paper, the thermal characteristics were evaluated in the high-speed ball-end milling of hardened steal (HRe 42). Experimental work was perform ed to find the optimal cutting environment to increase the tool life at a c utting speed of 210 m/min. Dry, wet and compressed chilled air at -9 and -3 5 degreesC as the cutting environment were investigated. The implanted ther mocouple technique was used for temperature measurement. A K-type thermocou ple, implanted in a hole in the workpiece, was directly cut in order to mea sure the temperatures of the shear zone in the cutting process. The cutting temperatures were about 790, 350, 540, and 450 degreesC in dry, wet, and c ompressed chilled air at -9 and -35 degreesC, respectively. For the ball-en d milling of hardened steel, the cutting environment for compressed chilled air at -9 degreesC provided the best tool life among all the cutting envir onments. Although the wet condition had the most effective cooling, it prov ided the worst tool life. (C) 2001 Elsevier Science B.V. All rights reserve d.