Investigation of the machinability by milling of the laser sintered Inconel 625/NiTi-TiB2 composite

OBRABOTKAMETALLOV Vol. 23 No. 1 2021 TECHNOLOGY Fig. 1. Workpiece clamped in the dynamometer teeth z = 4. Based on the recommendations on the processing modes of heat-resistant alloys for the ZhT641 mill and the analysis of the literature [4, 9, 11, 22], the feed per tooth S z = 0.04 mm/tooth was selected for the experiments. The mills were fi xed in a collet chuck with the same overhang, its value being 24 ± 0.5 mm. The wear of the mills and the cutting forces were measured to assess the quality and quantity of the experimental results. Tool wear was assessed by the fl ank chamfer. The wear chamfer was measured on a UIM 21 microscope on each tooth of the mill. The cutting forces were determined using a Kistler 9257B dynamometer (Switzerland). The measurements were carried out in three mutually perpendicular directions (Fig. 1). To evaluate the results, the total force   2 2 x y F F F was used; it acted in a plane perpendicular to the axis of the mill. The dynamometer, mounted on a special plate, was fi xed in a machine vise. Prior to the experiments, mounting holes were drilled in the workpiece to fi x it to the dynamometer with four screws (Fig. 1). To solve the problem of choosing the cutting speed, processing was performed at three cutting speeds: V 1 = 25 m/min; V 2 = 35 m/min, and V 3 = 50 m/min. The feed per tooth, the depth and width of milling re- mained constant: S z = 0.04; B = 4; t = 1. The wear of the mills was measured at the same intervals. To determine the optimal depth and width of the cut for the mill resistance to be the highest, three vari- ants of t and B ratio were selected: t = B ; t = B /4; t = B /16. This provided the same amount of the cut layer per unit of time, i.e. the product of t 1 B 1 = t 2 B 2 = t 3 B 3 for all three variants of the selected modes remained the same and maintained the same processing performance. The cutting speed was 25 m/min, the feed speed was S z = 0.04 mm/tooth. The cutting techniques are shown in Fig. 2. So, for mill No. 1, the depth and width of milling were t = 2 mm and B = 2 mm, respectively. For mill No. 2, the depth was t = 1 mm, therefore, the width increased to B = 4 mm. For mill No. 3, t = 0.5 mm, the width was B = 8 mm ( fi g. 2). The DynoWare software (Kistler, Switzerland) was used for data collection and analysis. Processing of all the received data was performed in the Microsoft Excel program. Results and discussion Fig. 3 shows the dependence of the amount of chamfer wear on the tooth fl ank surface on the machining time for cutting speeds of 50, 35, and 25 m/min (curves 1 , 2, and 3 , respectively). The graph shows that the