Investigation of force parameters acting on a single cutting insert made of ceramics in face milling of hardened steel

In the present paper, mathematical models for force parameters affecting single cutting insert made of oxide ceramics during finish milling of hardened steels are derived taking into account wear of inserts. Experiments showed that nitride Physical Vapor Deposition (VPD) coatings on oxide ceramics substrate CC6(Al2O3-TiC) produced by Moscow State University of Technology “STANKIN” provide at least 10% decrease of cutting forces. It was realized that cutting inserts wear influences the force parameters, especially axial force Px, that makes it possible to use those parameters as diagnosis indicators

Application of Adaptive Materials and Coatings to Increase Cutting Tool Performance: Efficiency in the Case of Composite Powder High Speed Steel

The paper proposes a classification of adaptive materials and coatings for tool purposes, showing the ability to adapt to external heat and power influences, thereby improving tool life. Creating a cutting tool made of composite powder high speed steels containing refractory TiC, TiCN, and Al2O3 compounds for milling 41CrS4 steel demonstrated the effectiveness of the adaptive materials. The tool material characteristics under the external loads’ influence and the surface layer adaptation to the heat–power exposure conditions were shown by the temperature field study using a semiartificial microthermocouple method (the level of fields is reduced by 20%–25% for 80% HSS + 20% TiCN), frictional interaction high-temperature tribometry (the coefficient of friction did not exceed 0.45 for 80% HSS + 20% TiCN at +20 and 600 °C), laboratory performance tests, and spectrometry of the surface layer secondary structures. Spectral analysis shows the highest spectrum intensity of TiC2 after 5 min of running in. After 20 min of milling (V = 82 m/min, f = 0.15 mm/tooth), dicarbide decomposes and transits to thermally stable secondary phase films of good lubricity such as TiO (maximum) and TiN (partially). There was an increase in tool life of up to 2 times (>35 min for 80% HSS + 20% TiCN), and a decrease in the roughness of up to 2.9 times (Ra less than 4.5 µm after 25 min of milling)

The metrological aspects of converters based on operational amplifiers used to measure the electrical parameters of oxide coatings

Background. The study is devoted to the issue of improving the accuracy of automated measuring instruments for the electrical parameters of oxide coatings. In measuring instruments, integrating circuits based on an operational amplifier, which is a universal amplifying device, are used to perform linear mathematical operations on analog signals. The disadvantage of the integrating circuit is the use of an operational amplifier, when using which it is necessary to take into account many parameters and factors that can affect the output signal, and hence the accuracy of the measured value. Materials and methods. Methods of indirect measurement of voltage and current on the studied sample with an oxide coating using the proposed structures of measuring channels are presented. It is shown that the parameters of operational amplifiers have a significant influence on the additive and multiplicative errors of measurement results, for the analysis of which a linear model of an operational amplifier is considered. Results. Based on the metrological analysis of the voltage measurement channel on the test sample, formulas for estimating additive, multiplicative and nonlinear error components are obtained. The contribution of multiplicative and additive parameters of the operational amplifier to the error of measurement results is analyzed in detail. Conclusions. Metrological analysis of the equivalent circuit of an operational amplifier with feedback has been performed, which can be used to estimate additive and multiplicative errors of circuits based on operational amplifiers widely used in instruments and measuring systems. It is shown that the total relative error of the developed channels for measuring current and voltage does not exceed 0.5%, which makes it possible to measure these values of the studied oxide coatings with guaranteed accuracy