Process capabilities related so part geometry. Very thin sections tevor rolling and thermotorrmng: "cDunky"s | 34 Manufacturing Analysis Some Basic Questions for a Start-Up Company Chap. 2 Minimum dimension of web v in. Figure Process capabilities related to part geometry. Very thin sections favor rolling and thermoforming chunky sections favor machining and injection molding from Introduction to Manufacturing Processes by J. A. Schey 1987. Reprinted with permission of the McGraw-Hill Companies . Hie thermoforming of plastic sheets is slightly above cold rolling in the graph. This also creates sections that are relatively thin and thus it competes with cold rolled metal products for many common items that require less structural rigidity. The middle part of the graph relates to processes that create more chunky looking parts of greater thickness the y axis in the figure . Finally note that the mold making procedures in sand casting prevent it from being selected if one of the dimensions is less than 5 millimeters inch . Accuracy Tolerances and Fidelity between CAD and CAM In all fabrication processes semiconductors plastics metals textiles or otherwise the physical limitations of each process have a major impact on the achievable accuracy. Each processing operation comes with a bounding envelope of performance that is constrained by the physical and or chemical processes that during fabrication are imposed on the original work material. This begs the following question How much fidelity will there be between a the specified CAD geometry tolerances and desired strength and b the final physical object that is manufactured In the best case scenario the CAD geometry will be perfectly translated into the fabricated geometry. Also the properties of the original piece of work material stock will be either unchanged or possibly work-hardened into an even more preferred state. Question 2 How Much Will the Product Cost to Manufacture Q 35 TABLE Routine Accuracies for Mechanical Processes One Thou Approximately 25 Microns Process Accuracy microns Accuracy inches
