This work studies the process feasibility of milling a metal-matrix composite based on Inconel 625 with added NiTi-TiB2 fabricated by direct laser deposition. The composite is intended for manufacturing turbine blades and it has strength characteristics on par with those of Inconel 625. However, the addition of TiB2 has improved its heat and wear resistance. This material is new, and its machinability has not been studied. The new composite was milled with end mill cutters, and recommendations were worked out on the cutting speed, feed per tooth, cutter flank angle, as well as depth and width of milling. The wear of cutter teeth flank was more intense. After the flank wear land on the back surface of a tooth had reached 0.11–0.15 mm, there was a sharp increase in the forces applied which was followed by brittle fracture of the tooth. Milling at a speed of 25 m/min ensured 28 min of stable operation. However, afterwards the critical wear value of 0.11 mm was quickly approached at a cutting speed of 50 m/min, and critical wear followed after 14 min. Dependencies of the cutting forces vs. time for all the selected cutting speeds and throughout the entire testing time period have a tendency to increase, which indicates the influence of cutter wear on the cutting forces. It was found that the durability of the cutters increases with an increase in the milling width and a decrease in the milling depth.

Introduction. The processing capability of milling a metal-matrix composite based on Inconel 625 with the addition of NiTi-TiB2, obtained by laser sintering, is investigated. The composite is intended for turbine blades manufacture and has strength characteristics close to Inconel 625, however, due to the addition of TiB2, its’ heat- and wear resistance is higher. This material is new; its machinability has not been studied yet. The aim of the work is to determine the technological capabilities of milling with end mills of this composite. Investigations. The new composite is milled with end mills, and recommendations on the selection of cutting speed, milling depth and width are obtained. Experimental Methods. Measuring end mill wear and cutting force. Wear is assessed by the flank chamfer using a microscope, and cutting forces are measured with a Kistler 9257B dynamometer. Milling is carried out at three speeds: 25, 35 and 50 m/min. To determine the optimal parameters of the depth and width of milling, the following ratios are used: 1: 1, 1: 4; 1:16, while the volume of chips removed per unit of time remained constant for all ratios. Results and Discussion. The back surface of the cutter teeth wears out more intensively. After reaching the wear chamfer along the flank surface of a value equal to 0.11 - 0.15 mm, there is a sharp increase in forces and brittle destruction of the tooth. Milling at a speed of 25 m/min guaranteed 28 minutes of stable operation, after which the amount of wear quickly approached the critical value of 0.11 mm, at a cutting speed of 50 m/min, critical wear occurred already after 14 minutes. The dependences of the cutting force on time for all selected cutting speeds, throughout the test time, have an increasing character, which indicates the effect of wear of cutters on cutting forces. It is found that the durability of cutters increases with increasing width and decreasing the depth of milling.

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