SPC专业术语
1、管制上限/管制下限:UCL / LCL Control limit. A line (or lines) on a control chart used as a basis for judging the significance of the variation from chart point to chart point. Variation beyond a control limit is evidence that assignable causes are affecting the process. Control limits are calculated from process data and are not to be confused with engineering or administrative specifications. A control chart usually displays a lower control limit (LCL) and an upper control limit (UCL). 管制界线。 用在管制图中当作点到点之间变异的衡量基准。 超出管制界线的变异可以证明某些原因会影响制程。 管制界线是从制程的数据来计算,不要和规格界线混淆。 通常管制图会显示管制下限 (LCL) 及管制上限 (UCL) 。 注 : 一般而言 , UCL 与 LCL 的位置为平均值的正负三个标准差。
2、制程准确度:Ca The deviation of the process mean from the midpoint of the specification limits. 衡量制程之实际平均值与规格中心值之一致性自生产中所获得产品资料的实际平均值与规格标准值间偏差的程度。
3、制程精密度: Cp / Capability of process. The greater the number, the better the process is capable of meeting the specification limits. A process is judged to be capable when CP is at least 1.0. 衡量制程之变异宽度与规格公差范围相差之情形。 一般而言 , CP 至少大于一才可以开始量产 , 否则因变异产生的成本会过高。
4、制程能力指数: Cpk Process Capability index related to both dispersion and centeredness. 关于分散与集中的制程能力指针。 同时考虑变异宽度与制程标准值之综合性制程能力指针。 综合 Ca 与 Cp 两值之指数。
5、CpL Distance between the process mean and the lower specification limit scaled using the capability sigma. 制程标准值与规格下限之间的差距值。
6、CpM Process capability index that is affected by the difference between the sample mean and the target value. 受样本中心值与规格中心值之差所影响的制程能力指针 。
7、CpU Distance between the process mean and the upper specification limit scaled using the capability sigma. 制程标准值与规格上限之间的差距 , 通常用在单边规格。
8、CR The reciprocal of CP. The smaller the number, the better the process is capable of meeting the specification limits. CR*100% is the percentage of the specification band used up by the process. CP 的倒数。这个数愈小,制程愈能和规格限制相交。 CR 百分比则代表制程中所耗损的规格宽度。
9、Pp Most commonly used process performance index. This is a more reliable measure of process performance for folded normal distribution since folded normal distribution is one-sided. 此为对于交叉常态分配更可信赖的制程能力量测指针,因为交叉常态分配呈现单边分配。
10、PpK Process performance index related to both dispersion and centeredness. This index is not suitable for folded normal distribution, which is one-sided. 同时考虑变异宽度与制程标准值之综合性制程能力指针。 但,这指针不适合交叉常态分配,因它是单边分配。
11、PpL Distance between the process mean and the lower specification limit scaled using the process standard deviation. This index is not suitable for folded normal distribution, which is one-sided. 制程标准值与规格下限之间的差距值。 但,这指针不适合交叉常态分配,因它是单边分配。
12、Ppm Process performance index that is affected by the difference between the sample mean and the target value. 受样本中心值与规格中心值之差所影响的制程能力指针。
13、PpU Distance between the process mean and the upper specification limit scaled using the process standard deviation. This index is not suitable for folded normal distribution, which is one-sided. 制程标准值与规格上限之间的差距。但,这指针不适合交叉常态分配,因它是单边分配。
14、PR PR. Reciprocal of PP. PP 的倒数。
15、峰度 Kurtosis A measure of peakedness. The population kurtosis is given by the fourth moment over the square of the variance. This ratio equals 0 for any normal distribution. A positive ratio indicates an excess of values in the neighborhood of the mean (with a depletion of the "flanks" of the curve representing the distribution). and a negative ratio corresponds to a curve with a flatter top than the normal curve has. 尖峰的量测指针。 最常用的峰度是四倍的动差乘上变异数的平方。 对于任何常态分配而言,这比率为 0 。 正机率意指超出平均数的邻近值,而负机率则指超出常态的曲线。
16、偏态 Skewness A measure of departure from normality. A distribution is skewed if it isn't symmetric but has more cases (a "tail") toward one end of the distribution than the other. If the tail is toward larger values, the distribution is positively skewed, or skewed to the right. If the tail is toward smaller values, the distribution is negatively skewed, or skewed to the left. 衡量从常态分配的偏移量。 若分配不匀称则会偏斜,朝向某一边,呈现单尾。 若偏向较大的值,则分配呈现正偏差,反之则呈现副偏差。