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The use of the following quality-control instruments in the machining of cylindrical liners at repair shops is considered: Shewhart charts (of moving-range and individual-measurement types) and histograms for analysis of the adjustment precision. A monitoring checklist has been developed for determining the losses due to all defect types. Interchangeability among groups for piston–liner assemblies completely eliminates wasted inventory.

The application of classical quality control tools in the processing of cylinder liners for repair size is considered: Shewhart cards of sliding ranges and individual values, as well as histograms for analyzing the accuracy of the technological process control. A checklist has been developed to identify waste and losses for all types of defects. The method of intergroup interchangeability for the pistonsleeve joint, which completely eliminates inventory backup, is substantiated and implemented. Keywords control, quality, control tool, cylinder liner, selective assembly. metr@rgau-msha.ru

The theoretical substantiation of the method of relative interchangeability in cylindrical joints with preload is given. Examples of connection of shafts with a repairable defect and parts with holes with an irrepairable defect and on the contrary at maintaining of required accuracy of joint on limiting preload are given. Keywords interchangeability, tolerance, size, fit, preload, repairable and irrepairable defect metr@rgau-msha.ru

A formula for the theoretical tolerance in fitting is derived by analysis of the components in the model of parametric failure for joints with interference. The formula takes account of the life of the joint and the specified probability of fault-free operation. It is found that selection of the fit without a margin of precision does not ensure the necessary reliability of the joint, while correct selection of the margin of precision extends the fault-free operation of the joint.

The urgency of research on the issues of substantiating the requirements for the accuracy of measurements of linear dimensions has substantiated. The main differences between the means for measuring external and internal dimensions have formulated. The factors influencing the choice of measuring instruments have considered. Specific additional measurement errors associated with the alignment of the measurement line with the hole diameter have described. A comparative analysis of the possibility of using various types of bore gauge to control the internal dimensions of holes during machine repair has carried out. The results of an experimental evaluation of the components of the measurement error of a two-point bore gauge have presented. The criterion for the selection of measuring instruments for measuring the holes of objects of maintenance of machinery and equipment has been substantiated. Recommendations have given aimed at improving the accuracy of measuring the holes of parts during the repair of machinery and equipment.

The foundations of the modern approach to quality management at enterprises also include elements of metrological support, which gives a certain effect from control. Universal measuring instruments for linear quantities are widely used in single and small-scale production, as well as in the repair of machines, it is with them that engineers first get acquainted when conducting laboratory measurements. Versatile measuring instruments also include a lever micrometer that can be used for absolute and relative measurements. The article discusses the issues of improving the method of relative measurements of deviations using a lever micrometer with deviations outside the measurement range of the reader, and provided that the tolerance does not go beyond the measurement. Using the technique of relative measurements with a lever micrometer will allow you to quickly perform a large number of measurements in a short time with the required accuracy.

The article presents a mechanism for analyzing the costs of the process from the point of view of assessing the effectiveness of the functioning of the quality management system at mechanical engineering enterprises of repair profile. The analysis of the costs of the process can be carried out in four directions: analysis of the effectiveness and efficiency of the process, analysis by type of costs, analysis of the effectiveness of measures to improve the process, comparison of the amount of costs for compliance and losses from non-compliance with the main economic indicators of the economic activity of the enterprise. Each direction can be applied independently, but in order to achieve reliable results and optimize the cost of quality, it is necessary to analyze the cost of quality in the four proposed directions. We analyzed the costs of repairing KAMAZ engines in four directions and came to the following conclusion: the introduction of a process cost management system allows us to timely identify process inconsistencies and take measures to eliminate them and reduce the risk of occurrence in the future, it is necessary to increase the amount of preventive costs in order to shift the break-even point right, it is necessary to take measures that actually prevent the occurrence of possible problems, the costs of compliance and losses from inconsistencies in sales are significant, therefore, measures should be taken to identify, analyze and assess the risk of inconsistencies in production and corrective actions to reduce the share of costs in total sales volume.

Features of quality assurance of production at machine-building enterprises of repair profile are considered. It is revealed that a large number of methods and means of restoring worn parts are used in the repair of machines − mechanical processing, surfacing and welding, metallization and spraying, electrolytic build-up, plastic deformation, and many others. A critical description of the existing theoretical positions on the choice of the most appropriate ways to restore details is presented. It is revealed that the existing methods are based on the criteria of manufacturability, durability and economy and consider the problem of whether it is appropriate to choose a particular method of restoration for only one part forming a joint. A model has been developed to optimize the cost of repairing parts that form a joint, taking into account both the cost of restoring each part and the cost of processing them. Calculations are made for a certain probability of failure and a given resource according to the criterion of the lowest total costs.