Sustainable Lot Size in a Multistage Lean-Green Manufacturing Process under Uncertainty

Abstract

Optimal lot sizing is the primary tool applied by lean practitioners to reduce inconsistency in the manufacturing system to cut down inventories, which are often considered as a type of waste in the lean culture. Managers attempt to consider environmental impacts of the manufacturing system and find ways to reduce these effects while making efforts to achieve environmental protection. From a sustainability standpoint, carbon emissions are the major source of environmental contamination and degradation. In this context, this research provides an economic production quantity model with uncertain demand and process information in a multistage manufacturing process. This imperfect manufacturing process produces defective products at an uncertain rate, and is reworked to convert them into perfect quality products and reduce wastages. To control this uncertainty in the manufacturing process, the decomposition principle and the signed distance method of fuzzy theory are applied. The manufacturing process is analyzed with regard to environmental concerns, and a sustainable lot size is obtained through an interactive Weighted Fuzzy Goal Programming (WFGP) approach for the simultaneous achievement of economic and environmental sustainability. An experimental study is performed to verify the practical implication of the model, and results are evaluated through a sensitivity analysis. Important managerial insights and graphical illustrations are provided to elaborate the model.

Effects of Preservation Technology Investment on Waste Generation in a Two-Echelon Supply Chain Model

“…These discarded deteriorated products have an adverse impact on the economic, social and environmental level. A multi-stage production system under uncertainties and process imperfection was studied in Tayyab et al [24]. From an environmental point of view, disposing of deteriorated products contributes to additional greenhouse gas (GHG) emissions.…”

Joint Inventory and Pricing Policy for an Online to Offline Closed-Loop Supply Chain Model with Random Defective Rate and Returnable Transport Items

“…Sarkar et al [58] studied warranty, optimal run time with inspection errors in the imperfect production system, and Kang et al [59] discussed optimal ordering policies for the imperfect production system. Recently, Khanna et al [60] considered two-level credit policies with imperfect quality, Tayyab et al [61] considered process uncertainty, and Tayyab et al [62] studied the multistage imperfect production system. The majority of the existing literature considered rework or scrap option for defective items, however, this paper considers salvage option for defective items.…”

Integrated Vendor–Buyer Lot-Sizing Model with Transportation and Quality Improvement Consideration under Just-in-Time Problem

“…In this case, these defective products are generated and have an impact on the manufacturing process and will lead to a disruption in the inventory management systems within the supply chain. Accordingly, the vendor incurs additional costs for reworking a product in order to restore its quality [16]. To improve the process quality, investment in quality improvement and production need to be linked in the model to analyse their effects on inventory replenishment decisions.…”

“…The value of p is the solution that leads to the quality-adjusted optimal lot size [27]. Consider a restriction to Equations (15) and (16), where 0 ≤ p 0 ≤ p ≤ 1. This shows that if p ≤ 1, then a vendor requires an investment function on quality improvement to improve the production process so that p is fully expected to be near the value of 1 (perfect quality).…”

“…Defective products can be generated during production runs, and additional costs are incurred for rejecting, reworking, and repairing the product. Moreover, there are external costs including returning the product, refunding or exchanging, or resolving customer complaints while trying to retain customer loyalty [16]. As a result, these failure costs can significantly affect a firm's profit in the short and long term.…”