Abstract
The capacity and capability of flexible manufacturing system varies with different market demands. To satisfy the requirements of performance expressions, avoid the problem of combinatorial explosion and consider the influence of intermediate buffer stations, a new reliability modelling and evaluating methodology for repairable non-series hybrid flexible manufacturing systems with finite buffers is proposed using an extended vector universal generating function technique. For repairable modular machines, the Markov models of modular machines are established using stochastic process analysis and the corresponding theoretical steady-state probability in various states is obtained. Furthermore, the original system in combination with multi-state reliability measures of buffer stations is equivalent to a system with independent machines which can be expressed by vector u-functions. Based on the probability distributions of the states of subsystems, the composition operators for series connections and parallel connections are defined. Consequently, the entire system is simplified to one component represented by the polynomial universal generating function. In particular, reliability indicators and measurement models are given to assess the system’s reliability through promoting the basic ones. Finally, a practical case of engine head machining line is utilized to verify the effectiveness of the method. The results demonstrate that the use of vector universal generating functions can describe the system structure and states more appropriately while providing efficient assessment.
Highlights
A non-series multi-stage manufacturing system refers to a system that involves multiple stages to complete a final product, where several machines or workstations are utilized at the same stage to meet the productivity and line-balance requirements.[1]
In section ‘Problem statement’, we describe the multi-state reliability modelling issue and propose six hypotheses as the basis for follow-up work
universal generating function (UGF) of the entire system was obtained by parallel and series composition operators combining system structure and states, and reliability indicators in vector were proposed
Summary
A non-series multi-stage manufacturing system refers to a system that involves multiple stages to complete a final product, where several machines or workstations are utilized at the same stage to meet the productivity and line-balance requirements.[1]. Zhang et al.[17] developed a modular model for multistage series manufacturing system with consideration of rework and products polymorphism based on extended stochastic Petri nets He et al.[18] proposed an integrated predictive maintenance strategy considering product quality level and mission reliability state regarding the intelligent manufacturing philosophy of prediction and manufacturing. The multi-state reliability model of repairable series–parallel flexible manufacturing system with finite buffers is established, and some reliability indicators such as steady-state availability, theoretical production rates, utilization rates, efficient production rates and production loss are given. Aiming to describe more clearly the multistate reliability modelling problem of repairable nonserial multi-state manufacturing systems with finite buffers, six hypotheses are proposed as the basis for follow-up work. Assuming that all the machines in the first stage have enough workpieces, the actual steady-state probability and non-steady-state probability of machine M1j in state k(2 ł k ł mij) can be obtained, respectively, by. Assuming all the machines in the last stage has enough stock space to ensure smooth output, the actual steady-state probability and non-steady-state probability of machine Mmj at stage Sm in state k(2 ł k ł mij) can be obtained, respectively, by
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