In practice, customers can decide whether to buy an extended warranty or not, at the time of item sale or at the end of the basic warranty. In this paper, by taking into account the moments of ...customers purchasing two-dimensional extended warranty, the optimization of imperfect preventive maintenance for repairable items is investigated from the manufacturer's perspective. A two-dimensional preventive maintenance strategy is proposed, under which the item is preventively maintained according to a specified age interval or usage interval, whichever occurs first. It is highlighted that when the extended warranty is purchased upon the expiration of the basic warranty, the manufacturer faces a two-stage preventive maintenance optimization problem. Moreover, in the second stage, the possibility of reducing the servicing cost over the extended warranty period is explored by classifying customers on the basis of their usage rates and then providing them with customized preventive maintenance programs. Numerical examples show that offering customized preventive maintenance programs can reduce the manufacturer's warranty cost, while a larger saving in warranty cost comes from encouraging customers to buy the extended warranty at the time of item sale.
•A two-dimensional PM strategy is investigated.•Imperfect PM strategy is optimized by considering both two-dimensional BW and EW.•Customers are categorized based on their usage rates throughout the BW period.•Servicing cost of the EW is reduced by offering customized PM programs.•Customers buying the EW at the time of sale is preferred for the manufacturer.
In order to provide a reliable service and supply the demand most of the time, all generators in a power grid should be subjected to an effective maintenance plan. The smarter the maintenance ...performed could result in a better performance of the system. However, a challenge is to minimise maintenance costs that do not compromise the benefits. Considering these facts, this study presents a reliability-based smart-maintenance approach of generators to compute the net-maximum economic benefit. The approach is derived from Kijima model type I to characterise the impact of maintenance over the component's virtual age, and Markov chains to model the component's lifetime. To achieve a more realistic model, generators' failure and repair rates are considered time-dependent variables. Then, the optimum preventive maintenance schedule is obtained by using an advanced algorithm named accelerated quantum particle swarm optimisation in combination with sequential Monte Carlo simulation. The effectiveness of the approach is investigated through a case study with four different scenarios: (i) no preventive maintenance plan, (ii) yearly periodic preventive maintenance, (iii) reliability-centred maintenance and (iv) smart maintenance. The results suggest that the approach is convenient for power system generators and delivers a significant knowledge contribution in the area of maintenance.
► To review existing research on maintenance and warranty. ► To classify the articles into different categories. ► To find knowledge gaps. ► To propose future research and new applications.
Along ...with increasing the warranty period for complex systems, reducing the warranty servicing costs has become an issue of great importance to the manufacturers. One possible way to reduce the expected warranty servicing cost is by making sound decision on the product warranty and maintenance strategies. Therefore, warranties (basic warranty and extended warranty) and maintenance (corrective and preventive) are strongly interlinked and of great interest to both manufacturers and customers. This paper is the first identifiable academic literature review to deal with warranty and maintenance. It provides a classification scheme for the articles that link warranty and maintenance published between 2001 and 2011 covering 44 journals and proposes a taxonomy scheme to classify these articles. Nine hundred articles were identified for their relevance to warranty and were carefully reviewed. One-hundred and twenty-two articles were subsequently selected for their relevance to maintenance and included in the classification.
Designing preventive maintenance (PM) policies that ensure smooth and efficient production for large-scale manufacturing systems is non-trivial. Recent model-free reinforcement learning (RL) methods ...shed lights on how to cope with the non-linearity and stochasticity in such complex systems. However, the action space explosion impedes RL-based PM policies to be generalized to real applications. In order to obtain cost efficient PM policies for a serial production line that has multiple levels of PM actions, a novel multi-agent modeling is adopted to support adaptive learning by modeling each machine as cooperative agent. The evaluation of system-level production loss is leveraged to construct the reward function. An adaptive learning framework based on value-decomposition multi-agent actor–critic algorithm is utilized to obtain PM policies. In simulation study, the proposed framework demonstrates its effectiveness by leading other baselines on a comprehensive set of metrics whereas the centralized RL-based methods struggles to converge to stable policies. Our analysis further demonstrates that our multi-agent reinforcement learning based method learns effective PM policies without any knowledge about the environment and maintenance strategies.
•Apply Deep Multi-Agent Reinforcement Learning to PM problem in manufacturing system.•Incorporate multiple levels of PM actions with imperfect maintenance effects.•Avoid space explosion by using Decentralized Partially Observable MDP (Dec-POMDP).•Demonstrate the proposed method by applying it to manufacturing applications.
A New Approach on Preventive Maintenance in Industry Crăciun, Ioan; Chifan, Florin; Dumitraş, Cătălin Gabriel
Bulletin of the Polytechnic Institute of Iași. Machine constructions Section,
06/2023, Letnik:
69, Številka:
2
Journal Article
Recenzirano
Odprti dostop
The role of maintenance in industry is important to ensure optimal performance, reliability and longevity of equipment, machinery and infrastructure. This maintenance ensure the continuity of the ...production with minimal losses. The present paper present the types of maintenance and based on this it focused on developing a generalized software which can be applied mainly in mechanical production industry. The main positive aspects of the software are: it represent an open source through the option of adding equipment, it can deliver sheets with costs of preventive maintenance and lists of personnel. Maintenance activities play a significant role in supporting the production process, minimizing downtime, reducing costs and increasing overall operational efficiency.
This paper integrates production, maintenance, and quality for an imperfect process in a multi-period multi-product capacitated lot-sizing context. The production system is modeled as an imperfect ...machine, whose the status is considered to be either in-control or out-of-control. When the machine is out of control, it produces a fraction of nonconforming items. During each period, this machine is inspected and imperfect preventive maintenance activities are simultaneously performed to reduce its age, proportional to the preventive maintenance level. The objective is to minimize the total cost, while satisfying the demand for all products. Our optimization model allows for a joint selection of the optimal values of production plan, and the maintenance policy, while taking into account quality related costs. A solution algorithm is developed and illustrative numerical examples are presented. It is found that the increase in PM level leads to reductions in quality control costs. Furthermore, if the cost of performing PM is high to the point where it is not compensated for by reductions in the quality related costs, then performing PM is not justifiable. Finally, using non-periodic preventive maintenance with the possibility of different preventive maintenance levels may result in an improvement of the total cost.
•We integrate production, maintenance, and quality.•We evaluate all the expected costs.•Our model allows for a joint selection of the optimal values.•A solution algorithm is developed.•Increasing PM level will decrease quality control costs.
•We consider a two-dimensional extended warranty with PM for repairable deteriorating products.•Different product utilization rates have different effects on product deterioration.•Classifying ...customers based on product utilization is important.•Offering different customers with different PM policies can effectively reduce the warranty cost.
This study proposes a customized two-dimensional extended warranty policy, in which customers are classified into three categories with different operating conditions according to their maintenance records in the basic warranty period, and then different preventive maintenance (PM) schedules are applied to customers in the different categories. This study investigates the effects that the classification of a customer and the time-usage ratio of the repairable deteriorating product have on breakdowns of such a product to effectively manage the total costs within the extended warranty period. Periodic and non-periodic preventive maintenance programs are both considered to meet different customer requirements to ensure that product reliability would not be gradually unacceptable. By adopting the proposed extended warranty approach, customers with high utilization rates could have satisfactory reliability on their products by performing more frequent PM activities, while those with low and average utilization rates could reduce the cost of PM within the extended warranty period, and also enjoy acceptable product availability. The results show that the classification of customers into different categories cannot only be beneficial by providing an effective mechanism to reduce the warranty costs, but also be a valuable competitive marketing strategy for product providers.
Maintenance is essential in keeping wind energy assets operating efficiently. With the development of advanced condition monitoring, diagnostics and prognostics, condition‐based maintenance has ...attracted much attention in the offshore wind industry in recent years. This paper models various maintenance activities and their impacts on the degradation and performance of offshore wind turbine components. An integrated maintenance strategy of corrective maintenance, imperfect time‐based preventive maintenance and condition‐based maintenance is proposed and compared with other traditional maintenance strategies. A maintenance simulation programme is developed to simulate the degradation and maintenance of offshore wind turbines and estimate their performance. A case study on a 10‐MW offshore wind turbine (OWT) is presented to analyse the performance of different maintenance strategies. The simulation results reveal that the proposed strategy not only reduces the total maintenance cost but also improves the energy generation by reducing the total downtime and expected energy not supplied. Furthermore, the proposed maintenance strategy is optimised to find the best degradation threshold and balance the trade‐off between the use of condition‐based maintenance and other maintenance activities.
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