Experimental investigation of a novel machining strategy for rough turning using variable feed rate

Abstract

The life of a tool is affected by many factors such as cutting speed, depth of cut, chip thickness, tool geometry, workpiece material, cutting fluid and the rigidity of the machine tool. This paper introduces the innovative turning strategy of variable feed turning. The workpiece material was AISI 1050, and two types of TiN-coated insert (CNMG-120408 (NC3020) and DNMG 150608-NM4 WPP20) were used as cutting tools in the machining tests. A thorough investigation was carried out on the effect on tool life of a gradual feed rate at a constant depth of cut and cutting speed with no cooling fluid. The feed rate was gradually increased twice every millimetre at the beginning of turning and kept constant for the rest of the cut. Turning experiments were conducted with both constant and variable feed rates. Brand new inserts were deployed in the experiments related with constant feed rate for each time period. Comparisons showed the significant influence of the variable feed rate. Apart from the reduction in initial wear, the new turning strategy produced very positive results regarding tool wear in the moderate wear zone, and a considerable increase of 32 % in tool life was achieved. Moreover, with the new strategy, total tool life was prolonged by up to 35 %.