Low Volume Plastics Manufacturing 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. This paper extends previous work [1] with component cost and lead-time models developed from extensive industry data. The application is an electrical enclosure consisting of two parts produced by a variety of low to high volume manufacturing processes including CNC machining, fused deposition modeling, selective laser sintering, vacuum casting, direct fabrication, and injection molding with soft prototype and production tooling. The viability of each process is compared for 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 US$0.35 per enclosure for ten thousand assemblies produced via injection molding to US$49.30 per enclosure for one hundred assemblies produced via fused deposition modeling. The results indicate the cost and lead time advantages of the alternative processes; a flow chart is provided to assist process selection in engineering design.