An Environmental Analysis of Injection Molding

Abstract

This environmental analysis of injection molding highlights a few important points. The choice of injection molding machine type (hydraulic, hybrid or all-electric) has a substantial impact on the specific energy consumption (SEC). The SEC values for hydraulic, hybrid and all-electric machines analyzed are 19.0, 13.2 and 12.6 MJ/kg respectively (including auxiliaries, compounding and the inefficiency of the electric grid). For hydraulic and hybrid machines SEC seems to exhibit a decreasing behavior with increasing throughput. This derives from spreading fixed energy costs over more kilograms of polymer as throughput increases. For all-electric machines SEC is constant with throughput. When the polymer production stage is included in the analysis, the energy consumption values increase up to 100 MJ/kg. The overall injection molding energy consumption in the U.S. in a yearly basis amounts to 2.06 times 108 GJ. This value is of similar magnitude to the overall U.S. energy consumption for sand casting, and to the entire electricity production of some developed countries