可查明原因.ppt

* Control Chart Roadmap 控制图的路线图 Select the appropriate variable control 选择适当的变量控制 Select the data collection point 选择数据收集点 Select Type of Control Chart 选择控制图表的类型 Establish basis for subgrouping 建立子群基础 Determine sample size and frequency 确定样本的大小和频率。 Determine measurement method/criteria 确定测量的方法/标准 Determine gage capability 确定测量量器的能力 Perform initial capability study to establish control limits 进行最初的能力分析以建立控制界限 Set up forms for charting data 建立制图数据的表格 Prepare procedures 准备程序 Train personnel 人员培训 * Setting and Changing Limits 建立和改变控制界限 Develop initial control limits through a short term capability study. 通过短期过程能力分析建立最初的控制界限 Remove all outliers from the data. 除去所有数据的异常点 Do not recalculate control limits unless process has significantly improved or based on a predetermined revision period. 不要重新计算控制界限除非流程有明显的改进或根据原先预定的修订周期 Control chart limits are not constantly updated with new data. 控制图的上下界限不可以因为收集了新数据而经常改变更新 The goal is to improve the process over time to narrow the control limits. 目标是改进流程并逐步缩小控制界限 When do you widen the limits? 什么时候将控制限变宽呢？ * Control Charts for Variables Data 变量数据的控制图 X-bar 均值 Measures the aim or centre of the process 测量流程的目标或中心点 Monitors the change in the Mean of the variable across time 监控数据的均值随时间改变而变异 Range 极差 Monitors variability of the process over time 随时间的变化监控流程的变异 Sigma 西格玛 Similar to Range Chart 与极差图类似 Uses the sample estimate of Sigma 用样本来估计西格玛值 Individuals 单值 Similar to X-bar 与均值图类似 Plots individual points instead of the Mean 直接将每个单值而不是均值绘制于图表 Moving Range 移动极差 Similar to Range chart 与极差图相似 New range is plotted with each consecutive point 极差图是以每一个相连点间的新极差来绘制 Used with the Individuals chart 使用单值图 * Nature of the X-bar and R Charts 均值极差图的自然特性 Most sensitive (powerful) chart for tracking process excursions in the mean and the variation 对跟踪流程均值和极差偏移的图表最敏感 Assumes normal distribution of individuals 假设其单值属于正态分布 Subgroups means tend to produce normal distribution because of the central limit theorem 因为中心限原理,子组的均值能生成正态