An environmental analysis of injection molding
Name
76754427-MIT.pdf
Description
Full printable version
Size
10.47 MB
Format
Adobe PDF
Checksum (MD5)
e95b80f27ec932e8217aa90a2c12b75f
Author(s)
Thiriez, Alexandre
Advisor(s)
Timothy Gutowski.
Date Issued
2006
Publisher
Massachusetts Institute of Technology
Abstract
This thesis investigates injection molding from an environmental standpoint, yielding a system-level environmental analysis of the process. There are three main objectives: analyze the energy consumption trends in injection molding machinery, explore the environmental performance of different technological alternatives, and provide a transparent life cycle inventory (LCI) identifying the mayor players in terms of environmental impact. The choice of injection molding machine type (hydraulic, hybrid or all-electric) has a substantial impact on the specific energy consumption (SEC), energy used per kg of processed polymer. 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. As viscosity and specific heat capacity increase so does SEC. Finally, SEC varies greatly with part shape. The thinner and the greater the projected area of the part the greater the SEC.
(cont.) When the polymer production stage is included in the analysis, the energy consumption values increase up to 100 MJ/kg. After polymer production, injection molding and extrusion have the greatest environmental impact in the whole LCI. The overall injection molding energy consumption (excluding polymer production) in the U.S. on a yearly basis amounts to 2.06 x 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.
Description
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.
Includes bibliographical references (p. 82-90).
Subjects
Mechanical Engineering.
MIT Department
Massachusetts Institute of Technology. Department of Mechanical Engineering
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