PSI - Issue 81

Viktor Kovalov et al. / Procedia Structural Integrity 81 (2026) 297–304

304

random nature of tool degradation and the interdependence of system components. Thanks to this, the method can be effectively used not only for analysing the reliability of existing designs, but also for designing new types of cutters, in which reliability requirements are taken into account at the design stage. Thus, the results obtained combine the theoretical foundations of reliability modelling with the practical tasks of tool engineering. The proposed probabilistic and economically sound approach creates a scientific basis for increasing tool durability, reducing maintenance costs and improving the efficiency of heavy machinery manufacturing systems. Conclusions 1. The study of the operating conditions of assembled turning tools for heavy machine tools has made it possible to identify the main technological factors that affect their reliability. It has been established that alloy steels account for the largest share of the materials being processed (59%), and most tool failures (up to 79%) are associated with chipping, flaking and destruction of the cutting part. 2. A mathematical model of the reliability of an assembled cutter was developed based on the theory of semi- Markov processes. The model reflects the dependence of the readiness coefficient on the laws of distribution of the stability period (Weibull law) and recovery time (exponential law), which adequately describes the real processes of stochastic wear. 3. The determination of the rational level of reliability of the assembled cutter and its individual elements based on the criterion of reduced costs is justified. For the system as a whole, the optimal readiness coefficient is 0.64-0.68, and for the cutting plate - 0.75-0.82. Further improvement of these indicators leads to a disproportionate increase in the cost of processing. 4. It has been established that to ensure stable operation of the tool, it is necessary to replace the cutters at regular intervals after reaching the gamma-percentage stability period. This approach minimises equipment downtime and optimises maintenance schedules. 5. A probabilistic method for calculating the thickness of the cutting plate is proposed, which takes into account the laws of load distribution and the bearing capacity of the material. This provides the possibility of engineering design of cutters with a predetermined level of reliability. 6. The maintainability of cutter designs has been assessed. It has been determined that the repair time for individual elements ranges from 39 to 120 seconds, and the proportion of downtime associated with tool maintenance reaches 6-10% of the total system operating time. References Agrawal, C., Singh, R., Rathore, J., 2021. Cryogenic vs. wet turning of Ti-6Al-4V: tool wear, tool life, cost and CO ₂ analysis. 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