An Environmental Analysis of Injection Molding

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 10
⁸
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