功能建造6(沙济伦博士讲义分享).ppt

* * * * * From Jay Baron. * 这是硬碰软，形势一边倒。 奇怪的是结果比硬的更过。大概是测量误差了。 Figure 13 on page 21 shows a run chart for dimension #3 on the body side outer before and after assembly. This figure shows that even though the mean is away from nominal for four stamping runs, the assembly process is stable. However, when the mean shifted significantly closer to nominal at the start of the fifth run, the assembly variation increased. In this instance, maintaining a consistent stamping mean appears more important than the relative location of this dimension to nominal. 1-4批量时，虽然零件的值离开目标有距离，但是，装配后的组件还算稳定。可是，零件整修后，离目标值近了，组件反而不稳定了。 这里是软碰软的例子。典型的一加一除以二。得到的就是平均值。 * The tooling rework decision model presented in Figure 16 suggests manufacturers are unlikely to benefit from reworking dies for small mean deviations (less than X1). They should be able to either ignore these deviations or make a simple adjustment in the assembly tooling. In this region, manufacturers should not rework the tools regardless of Cpk compliance. At some level of mean deviation greater than X2, however, manufacturers may be unable to make a correction to the assembly process. In this region, manufacturers should rework the die before constructing screw-body prototypes because it is likely that they will ultimately have to rework the die. The region between X1 and X2 represents the unknown or functional build region. In this situation, reworking the die may or may not be less expensive than making a compensation in assembly. Values for X1 and X2 appear to depend on complexity and rigidity of the stamped part. The more complex/ less rigid a part, the larger the values for X1 and X2. Table 10 on page 26 provides recommended values for dimensions by part category based upon the historical data available. This table may be further refined to include tolerances. For instance, manufacturers may choose to define the gray area from 50% to 150% of the original tolerance. Therefore, for tolerances of +/- 1 mm, the gray area would