FUNDAMENTALS OF UNIT MANUFACTURING PROCESSES
To live well, a nation must produce well.
Dertouzos et al., 1989
Productivity isn't everything, but in the long run it is almost everything.
Throughout history a nation's wealth, standard of living, and status in the international community have directly benefitted from the nation's manufacturing capability. Transportation systems, energy generation and distribution, health care, construction, education, banking, and virtually every aspect of the modern way of life depend on the quality and affordability of manufactured products. U.S. manufacturing remains a significant portion of the nation's. economy but has experienced a loss in its global competitive position. One of the key factors contributing to the loss of manufacturing competitiveness and productivity has been a reduction in investment in manufacturing process research and development (R&D; Mettler, 1993).
This section provides an introduction to unit manufacturing processes, the basic building blocks of a nation's manufacturing capability. Manufacturing involves the conversion of raw materials, usually supplied in simple or shapeless forms, into finished products with specific shape, structure, and properties designed to fulfill specific requirements.
Chapter 1 sets the stage for the entire report by highlighting the importance of manufacturing to the nation's economy and providing an overview of the rest of the report.
Chapter 2 develops the technical foundations for the remainder of the report. Every unit process has five key process components: the workpiece material, process tooling, a localized workzone within the material, an interface between the tooling and the workzone, and the process equipment that provides the controlled application of energy. Advances in unit process technologies can be targeted at one or more of these components. The chapter categorizes unit processes in terms of the physical process by which the configuration or structure of a material is changed. This results in five distinct unit process families that are discussed in Part II:
- mass-change processes, which remove or add material by mechanical, electrical, or chemical means;
- phase-change processes, which produce a solid part from material originally in the liquid or vapor phase;
- structure change processes, which alter the microstructure of a workpiece;
- deformation processes, which alter the shape of a solid workpiece without changing its mass or composition; and
- consolidation processes, which combine materials such as particles, filaments, or solid sections to form a solid part or component.
- Even though this report primarily addresses the development of unit process technologies, a national emphasis in manufacturing must address at least three factors: process technologies, workforce education, and implementation. Process technologies will not contribute to overall improvements in manufacturing competitiveness without the nation possessing an educated, motivated workforce and with industries committed to making appropriate investments.
- The following criteria can be applied to evaluate projects in unit process R&D: How well does the project offer the inherent potential for cost-effective production and shaping of materials? Does it exploit the physical properties of an advanced material cost-effectively and in an unique way? Can it shorten the time to move a product technology from the research stage to commercialization? Does it provide a processing method that is inherently environmentally friendly? Is it applicable to a range of materials? Can it produce a variety of parts?