In this study we use a thermodynamic framework to characterize the material and energy resources used in manufacturing processes. The analysis and data span a wide range of processes from "conventional" processes such as machining, casting, and injection molding, to the so-called "advanced machining" processes such as electrical discharge machining and abrasive waterjet machining, and to the vapor-phase processes used in semiconductor and nanomaterials fabrication. In all, 20 processes are analyzed. The results show that the intensity of materials and energy used per unit of mass of material processed (measured either as specific energy or exergy) has increased by at least 6 orders of magnitude over the past several decades. The increase of material/energy intensity use has been primarily a consequence of the introduction of new manufacturing processes, rather than changes in traditional technologies. This phenomenon has been driven by the desire for precise small-scale devices and product features and enabled by stable and declining material and energy prices over this period. We illustrate the relevance of thermodynamics (including exergy analysis) for all processes in spite of the fact that long-lasting focus in manufacturing has been on product quality--not necessarily energy/material conversion efficiency. We promote the use of thermodynamics tools for analysis of manufacturing processes within the context of rapidly increasing relevance of sustainable human enterprises. We confirm that exergy analysis can be used to identify where resources are lost in these processes, which is the first step in proposing and/or redesigning new more efficient processes.

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In this paper, we present the formulation of a framework for the quantitative thermodynamic analysis of manufacturing processes and systems. Since manufacturing typically involves the input of high-quality material/energy and/or dissipation of low-quality energy/waste to manipulate a material, an approach that combines both the first and the second laws of thermodynamics is appropriate. This formulation helps emphasize that the improvement of manufacturing processes and systems is more a question of both utilizing the quantity and conserving the quality of energy than merely conserving energy. We conclude with two examples of its application, the first a comparison of metal casting technologies and the second a contrast between high-throughput CNC machining and a slower process rate grinding operation.

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