OBRABOTKAMETALLOV Vol. 25 No. 2 2023 technology 2) to evaluate the density of the coolants used and its wetting effect in laboratory conditions; 3) to establish the dependence of the index of the lubricating action of coolants on its density and wetting action simultaneously and separately; 4) to establish the accuracy of calculations of the indicator of the lubricating action of the coolant according to the derived dependencies; 5) to develop a methodology for predicting the lubricating properties of coolant based on laboratory tests. Research technique Investigation of the lubricating properties of a coolant In studies of the lubricating effect of a coolant, a friction machine of the model II5018 was used. The parameter for evaluating the lubricating effect was the real coefficient of friction µ. For the evaluation, water-based coolants were used, since this type is the most common in the production of metal parts. The applied coolants of various compositions were experimental developments of the company NPO Promekologiya LLC (Omsk). Therefore, all coolants were numbered and labelled as coolant 1, coolant 2, coolant 3, coolant 4, coolant 5, coolant 6, and coolant 7. The studies were carried out according to the “pad – roller”. The pad was made of solid titanium-tungsten-cobalt alloy 15% TiC–79% WC–6% Co, the roller was made of carbon structural steel 45 (0.45% C). The principle of operation of the machine presupposes the abrasion of a pair of samples pressed against each other with a force of R. The “pad–roller” test scheme used allows simulating turning: the role of the workpiece is played by a rotating roller made of the material being processed, and the role of the tool — by a pad made of tool material pressed against the roller. The research was carried out with a pressure force on the pad P = 1,000 N and a roller rotation speed n = 250 rpm corresponding to low modes. This was done purposefully, since with increasing modes, the friction force and wear of the pads and roller increases, and the coefficient of friction changes slightly. As a parameter of coolant efficiency by lubricating action, this paper proposes an efficiency coefficient Kc, which is equal to the ratio of the coefficient of friction arising from the use of coolant to the coefficient of friction while friction without coolant. The smaller the coefficient Kc, the more effective the coolant is in terms of lubricating action. Since the purpose of the studies was to develop a methodology for accelerated evaluation of the lubricating properties of coolant, at the next stage it was decided to select coolant parameters that could potentially affect the lubricating effect of a coolant and would not require the use of complex equipment for its evaluation. One of these parameters is the density (ρ, kg/m3), which is easy to estimate in the laboratory. Another property affecting the lubricating effect of a coolant is its wetting effect, which is estimated by the limiting wetting angle (Θ, degrees) [17]. Investigation of a coolant density Experimental estimation of the density of the coolant under investigation was carried out using analytical balance AND DL-200 with a discreteness of 0.001 g. The analytical balance used is shown in figure 1. During the tests, each coolant was poured into a measuring container. The volume of the studied coolant was 120 ml. The measuring container was put on the balance pan and held for Fig. 1. Analytical balance AND DL-200
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