Cost Optimization in Sheet Metal Manufacturing by Tuning the Sheet Metal Nesting Strategy Based on Sheet Utilization and Downstream Part Handling Costs

Abstract

The cutting of sheet metal blanks from raw sheet stock is a crucial process in the sheet metal fabrication industry. One of the primary cost drivers for this process is sheet utilization, which is the amount of raw material processed into a usable blank compared to the total raw material processed. Nesting is a method that efficiently packs blanks onto raw sheets with the aim of reducing scrap generation by improving material utilization. Modern nesting algorithms are quite successful at maximizing sheet utilization given an explicit set of available raw sheets and a set of blanks defined as candidates for nesting. Because of this, nesting efficiency and thus sheet utilization are primarily determined by the characteristics of the candidate blanks and the number of candidate blanks that can be nested together. Nesting strategies may be chosen to include the maximum number of possible candidate blanks for maximized efficiency. On the other hand, nesting strategies may instead restrict the available part candidates for the purpose of reducing sorting and handling complexities downstream of the cutting operation. In between these two extremes, it is hypothesized that there exists an optimum nesting strategy that balances improved sheet utilization with the negative cost effect of more intensive handling requirements. In this work, the effect of varying nesting strategies on sheet utilization is studied in the context of a sheet metal manufacturing operation with plant locations across the globe. Cost models are produced that inform the selection of a globally optimized nesting strategy, and throughput models are considered which inform the validity of cost-optimized strategies. Additionally, regional differences in cost drivers are studied, and an optimized nesting strategy is validated for deployment across global plant locations. This work provides a detailed approach to optimizing sheet utilization in sheet metal manufacturing through selection of an optimized nesting strategy.