| 摘要 |
<p>A process of establishing valid statistical dimensional tolerance limits for designs of detail parts that will enable accurate prediction of an economically acceptable degree of non-conformance of a large flexible end item assembly, having a set of predetermined dimensional tolerances, made from the detail parts, wherein the detail part tolerances are enlarged substantially compared to tolerances that would be necessary using an arithmetic 'worst case' approach to remain within the end assembly tolerances while remaining within preestablished stress limits of the parts. A preferred assembly sequence for assembling the parts into the assembly is selected and validated. Locations, numbers and size of coordination features to be machined in said detail parts are selected, by which the parts are located relative to each other and fastened together to form the assembly. Individual part statistical dimensional tolerances are established as a fabrication requirement for the parts that enable the parts to be economically produced and assembled into assemblies that meet the predetermined assembly dimensional tolerances. The individual part statistical dimensional tolerances are broader than conventional tolerances that are established to ensure acceptable assemblies when parts are assembled at the extremes of their tolerances, stacked in a worst case manner. The parts are produced to the individual statistical dimensional tolerances in a capable process, having a Cpk equal to at least 1.0, while holding the mean values of the statistically determined dimensions of the individual parts to within a predetermined percentage of the nominal dimension. The end item is assembled in accordance with the preferred assembly sequence by locating the parts relative to each other by reference to the coordination features. The properly located parts are fastened together as located, using the coordination features as the primary determinator of assembly configuration.</p> |
