A sustainable flexible manufacturing–remanufacturing model with improved service and green investment under variable demand

Environmental protection and the availability of natural resources help to maintain sustainability for manufacturing system. Reusing/remanufacturing economically viable used products, collected from end customers, has become an integral part of many supply chain operations. Remanufacturing with green investment plays an essential role in sustainable supply chain management by utilizing an environment-friendly approach. Considering this environmental, social, and economic development of society, this model mainly focuses on the flexibility of production rate under the multi-retailer based supply chain to satisfy customer's demand. In this study, the manufacturer produces final products from new raw materials and used collected products. Subsequently, the products are transported to retailers and sold along with their service facilities. A mathematical model of this flexible manufacturing–remanufacturing system is developed to improve the service and to maintain sustainability always. The global optimization is established theoretically and a proposition is developed. Through numerical experiments, the global optimality is also verified. Some special cases, along with a comparison graph, are also provided for the validation of this results. The obtained results indicate that the concerned idea of service facility helps the customer to choose products without hesitation and the supply chain management achieves the maximum profit under green investment. It is found that the proposed study converges over the fixed production rate and without service studies.