Hard Turning of Powder Metallurgical Cold Work Tool Steel Tempered in Different Tempering Temperature

Abstract

In this study, PM K390 cold work tool steel, which gives perfect results in the industry in cutting, boring, plastic injection casts and cold shaping applications, was tempered at three different temperatures. Turning experiments were conducted on the three work pieces tempered at different temperatures using CBN inserts and the performance characteristics were studied. Four different cutting speeds and four different feed rate value was used in the cutting experiments. CBN tool performance was evaluated based on machining force, surface roughness and tool wear. Cutting speed, feed rate, depth of cut and tool types were determined as processes parameters. Evaluating tool wear type and wear mechanism by tool makers’ microscope and SEM analysis. More ideal results were obtained in the processing of the work piece M3, to which a low tempering temperature was applied. In the turning of the PM K390 cold work tool steel, after thermal treatment, surface qualities were obtained that are close

to the ones obtained in grinding operations (<i>R_a</i>: 0.15 µm). According to the obtained results and taking into account the economy and surface quality, the suitable cutting parameters were considered as <i>f</i>: 0.05 mm/rev and <i>Vc</i>: 120-160 m/min.