Evaluation of Maintainability Index of a Mechanical System using Graph Theoretic Approach

In globalised economy, all mechanical systems need to be highly productive and efficient. Lead time reduction and defect reduction is big challenge for production managers in shop floor. Effective maintenance plays very crucial role in improving productivity of any production system. Therefore analysis of maintainability of a system is crucial. Maintainability is the design attribute of a mechanical system, which facilitates the various related maintenance activities and plays a significant role during the working period of any mechanical system. In this study, compressor is considered as mechanical system. Graph Theory Approach is suggested for the evaluation of the Maintainability Index of this system. Maintainability of a mechanical system is modelled in terms of the Maintainability Attributed Digraph, wherein the maintainability attributes are identified as the features or characteristics which determine and indicate the ease in the maintenance of a system. Nodes of the digraph represent the system maintainability attributes while their inter-relation is represented by the edges. This digraph is translated into a one-to-one matrix known as the Maintainability Permanent Matrix (MPM) and based on this matrix; the Variable Permanent Function for Maintainability (VPFM) is proposed, which is characteristic of the Mechanical system. Logical Ranking and numerical values are assigned to these attributes. After substituting these values in the MPM or the VPFM; Maintainability Index of the mechanical system is evaluated. Higher the value of the Index indicates higher the maintainability of the mechanical system. This procedure can be employed at the design stage of a product for the development of maintainable systems. This will also help in benchmarking the performance of a mechanical system with the best in industry.