DESIGN FOR MANUFACTURING:PROCESSES AND MATERIALS FOR PRODUCING THE DESIGN

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PROCESSES AND MATERIALS FOR PRODUCING THE DESIGN

The selection of the ideal processes and materials with which to produce a given design cannot be an independent activity. It must be a continuing activity that takes place throughout the design life cycle, from initial conception to production. Material selection and process selection need to be considered together; they should not be considered independently.

In considering the selection of materials for an application, it is usually possible to rule out entire classes of materials because of cost or their obvious inability to satisfy specific operational require- ments. But even so, with the acceleration of material development there are so many options for the functional design engineer that optimum selection is at best difficult. The suggested procedure for organizing data related to material selection is to divide it into three categories: properties, specifi- cations, and data for ordering.

The property category will usually provide the information that suggests the most desirable ma- terial. A property profile is recommended, where all information, such as yield point, modulus of elasticity, resistance to corrosion, and so on, is tabulated. Those materials that qualify because of their properties will stand out.

Each material will have its own specifications on the individual grades available and on their properties, applications, and comparative costs. The unique specifications of a material will distin- guish it from all competing materials and will serve as the basis for quality control, planning, and inspection.

Finally, the data needed when physically placing an order need to be maintained. This includes minimum order size, quantity breakpoints, and sources of supply.

In the final selection of a material, cost of the proposed material needs to be considered—hence the need for close association between material selection and process selection in connection with design.

Design evaluation invariably is in terms of a proposed material cost, which may be derived by analyzing the involved processing steps, including setup and lead-time costs along with the preproc- essed material cost.

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