Plastics Product and Process Design Strategies

Abstract

Plastic components are vital components of many engineered products, frequently representing 20–40% of the product value. While injection molding is the most common process for economically producing complex designs in large quantities, a large initial monetary investment is required to develop appropriate tooling. Accordingly, injection molding may not be appropriate for applications that are not guaranteed to recoup the initial costs. In this paper, component cost and lead-time models are developed from industry data for an electrical enclosure consisting of two parts produced by a variety of low to medium volume manufacturing processes including fused deposition modeling, direct fabrication, and injection molding with used tooling, soft prototype tooling, and hard tooling. The viability of each process is compared with respect to the manufacturing cost and lead time for specific production quantities of one hundred, one thousand, and ten thousand. The results indicate that the average cost per enclosure assembly is highly sensitive to the production quantity, varying in range from $243 per enclosure for quantity one hundred to $0.52 per enclosure for quantity ten thousand. The most appropriate process varies greatly with the desired production quantity and cost/lead time sensitivity. As such, a probabilistic analysis was utilized to evaluate the effect of uncertain demand and market delays, the result of which demonstrated the importance of maintaining supply chain flexibility by minimizing initial cost and lead time.