六西格瑪工序控制與工序能力教材-閱讀頁
2025-03-08 23:05本頁面
【正文】 requirements to specify the tolerance for a product’s characteristic 工序極限 (LPL and UPL)4 measures the variation of a process4 the natural 6? limits of the measured characteristic 控制極限 (LCL and UCL)4 measures the variation of a sample statistic (mean, variance, proportion, etc)35BPTL Confidential 6σ推行教材工序能力指數(shù)工序能力的兩種度量 :4工序潛力– Cp 4工序表現(xiàn)216。 Cpl 216。2 mm. Control of the length of the camshaft is critical to avoid scrap/rework.The camshaft is provided by external suppliers. Assess the process capability for this supplier.The data is available in . Data are collected in subgroups of 5 each.49BPTL Confidential 6σ推行教材Example 4Minitab:Stat ? Quality Tools ? Capability Analysis (Normal)50BPTL Confidential 6σ推行教材Example 451BPTL Confidential 6σ推行教材Example 5Histogram of the camshaft length suggests mixed populations. Further investigation revealed that there are two suppliers for the camshaft. Data were now collected on camshafts from each source without bining both. Subgroup size is 5 for each supplier.Are the two suppliers similar in performance?If not, what are your remendations?52BPTL Confidential 6σ推行教材Example 5MiniTab:Stat ? Quality Tools ? Capability Sixpack(Normal)53BPTL Confidential 6σ推行教材Example 554BPTL Confidential 6σ推行教材Example 555BPTL Confidential 6σ推行教材用 BoxCox 轉(zhuǎn)化后的工序能力分析4 When the process data are not normal, the Cpk or Ppk indices are not accurate or reliable, because these indices are puted on the basis that the data are normally distributed. 4 Dppm values associated with the indices will not be near to the actual performance when the normal curve does not model the actual data well.56BPTL Confidential 6σ推行教材4 If the process data are somewhat bellshaped but skewed, BoxCox transformation can be used to make the data normal before we assess the process capability.4 Remember to transform the specification limits too before we pute Cpk or Ppk! 用 BoxCox 轉(zhuǎn)化后的工序能力分析57BPTL Confidential 6σ推行教材Minitab:Stat ? Quality Tools ? Capability Analysis (Normal)用 BoxCox 轉(zhuǎn)化后的工序能力分析58BPTL Confidential 6σ推行教材Example 6Open the file named in the Day2 folder again. Compute the process capability with the specification limits:LSL: USL: 10Are the data normally distributed?Compute the process capability again with BoxCox transformation.用 BoxCox 轉(zhuǎn)化后的工序能力分析59BPTL Confidential 6σ推行教材Cpk of is reported in the SSAT package. This value is not reliable or accurate if the data are not normal. Data is not normalExample 6用 BoxCox 轉(zhuǎn)化后的工序能力分析60BPTL Confidential 6σ推行教材Example 6Cpk has increased from to 用 BoxCox 轉(zhuǎn)化后的工序能力分析61BPTL Confidential 6σ推行教材What’s “6?” Quality — Then4 Original Definition by Motorola:4 In the short term, the specification limits are at least 177。 Data cannot be adequately described on a continuous scale
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