sigma水平、公差范围、CPK与不良率(PPM)对照表

%T K（σ）Cpk PPM%T K（σ）Cpk PPM%T K（σ）Cpk PPM 1666.7%0.180.06800000.00107.5% 2.790.935270.868.0% 4.41 1.4710.34 769.2%0.390.13700000.00106.4% 2.820.944802.3667.6% 4.44 1.489 625.0%0.480.16600000.00105.3% 2.850.954371.9267.1% 4.47 1.497.82 454.5%0.660.22500000.00104.2% 2.880.963976.7566.7% 4.5 1.5 6.8 357.1%0.840.28400000.00103.1% 2.910.973614.2966.2% 4.53 1.51 5.9 303.0%0.990.33317310.00102.0% 2.940.983282.1265.8% 4.56 1.52 5.12 285.7% 1.050.35293800.00101.0% 2.970.99297865.4% 4.59 1.53 4.43 263.2% 1.140.38250000.00100.0%312699.864.9% 4.62 1.54 3.84 250.0% 1.20.4230200.0099.0% 3.03 1.012445.5464.5% 4.65 1.55 3.32 232.6% 1.290.43200000.0098.0% 3.06 1.022213.3764.1% 4.68 1.56 2.87 222.2% 1.350.45177000.0097.1% 3.09 1.032001.5663.7% 4.71 1.57 2.48 208.3% 1.440.48150000.0096.2% 3.12 1.041808.5163.3% 4.74 1.58 2.14 196.1% 1.530.51126016.7395.2% 3.15 1.051632.762.9% 4.77 1.59 1.84 192.3% 1.560.52118759.8894.3% 3.18 1.061472.7562.5% 4.8 1.6 1.59 188.7% 1.590.53111834.8193.5% 3.21 1.071327.3562.1% 4.83 1.61 1.37 185.2% 1.620.54105232.2892.6% 3.24 1.081195.361.7% 4.86 1.62 1.17 181.8% 1.650.5598942.9491.7% 3.27 1.091075.4761.3% 4.89 1.63 1.01 178.6% 1.680.5692957.3290.9% 3.3 1.1966.8561.0% 4.92 1.640.8654 175.4% 1.710.5787265.8790.1% 3.33 1.11868.4660.6% 4.95 1.650.7421 172.4% 1.740.5881859.0289.3% 3.36 1.12779.4260.2% 4.98 1.660.6358 169.5% 1.770.5976727.1488.5% 3.39 1.13698.9359.9% 5.01 1.670.5443 166.7% 1.80.671860.6487.7% 3.42 1.14626.2159.5% 5.04 1.680.4655 163.9% 1.830.6167249.9487.0% 3.45 1.15560.5959.2% 5.07 1.690.3978 161.3% 1.860.6262885.5386.2% 3.48 1.16501.4158.8% 5.1 1.70.3397 158.7% 1.890.6358757.9685.5% 3.51 1.17448.1158.5% 5.13 1.710.2897 156.3% 1.920.6454857.9084.7% 3.54 1.18400.1358.1% 5.16 1.720.2469 153.8% 1.950.6551176.1284.0% 3.57 1.19356.9857.8% 5.19 1.730.2103 151.5% 1.980.6647703.5383.3% 3.6 1.2318.2257.5% 5.22 1.740.1789 149.3% 2.010.6744431.1982.6% 3.63 1.21283.4257.1% 5.25 1.750.1521 147.1% 2.040.6841350.3382.0% 3.66 1.22252.2256.8% 5.28 1.760.1292 144.9% 2.070.6938452.3481.3% 3.69 1.23224.2556.5% 5.31 1.770.1096 142.9% 2.10.735728.8480.6% 3.72 1.24199.2256.2% 5.34 1.780.0929 140.8% 2.130.7133171.6180.0% 3.75 1.25176.8355.9% 5.37 1.790.0787 138.9% 2.160.7230772.6779.4% 3.78 1.26156.8355.6% 5.4 1.80.0666 137.0% 2.190.7328524.2478.7% 3.81 1.27138.9755.2% 5.43 1.810.0564 135.1% 2.220.7426418.7778.1% 3.84 1.28123.0354.9% 5.46 1.820.0476 133.3% 2.250.7524448.9577.5% 3.87 1.29108.8454.6% 5.49 1.830.0402 131.6% 2.280.7622607.6976.9% 3.9 1.396.1954.3% 5.52 1.840.0339 129.9% 2.310.7720888.1576.3% 3.93 1.3184.9554.1% 5.55 1.850.0286 128.2% 2.340.7819283.7475.8% 3.96 1.3274.9553.8% 5.58 1.860.0241 126.6% 2.370.7917788.0975.2% 3.99 1.3366.0753.5% 5.61 1.870.0202 125.0% 2.40.816395.0774.6% 4.02 1.3458.253.2% 5.64 1.880.017 123.5% 2.430.8115098.8274.1% 4.05 1.3551.2252.9% 5.67 1.890.0143 122.0% 2.460.8213893.7073.5% 4.08 1.3645.0452.6% 5.7 1.90.012 120.5% 2.490.8312774.3173.0% 4.11 1.3739.5752.4% 5.73 1.910.01 119.0% 2.520.8411735.4872.5% 4.14 1.3834.7352.1% 5.76 1.920.0084 117.6% 2.550.8510772.2971.9% 4.17 1.3930.4651.8% 5.79 1.930.007 116.3% 2.580.869880.0371.4% 4.2 1.426.6951.5% 5.82 1.940.0059 114.9% 2.610.879054.2270.9% 4.23 1.4123.3751.3% 5.85 1.950.0049 113.6% 2.640.888290.6070.4% 4.26 1.4220.4451.0% 5.88 1.960.0041 112.4% 2.670.897585.1269.9% 4.29 1.4317.8750.8% 5.91 1.970.0034 111.1% 2.70.96933.9569.4% 4.32 1.4415.650.5% 5.94 1.980.0029 109.9% 2.730.916333.4369.0% 4.35 1.4513.6150.3% 5.97 1.990.0024 108.7% 2.760.925780.1468.5% 4.38 1.4611.8750.0%620.002 Note: 1、 available for bilateral tolerance (双向公差适用）

2、 k（σ）对应于控制范围，σ是实际的计算值，如果客户规范公差范围对应的k值是2.34，对应的cpk是0.78，不良品率=19283ppm

3、 %T是实际控制6 σ占规范公差T的比例，假如实际6σ等于规范公差T，则CPk=1.0。CPK要达到1.33的水平，6σ=T*75%。

4. T%中的T是指±T中的T，而不是指整个公差带

举例： 1、 客户公差范围T=5，我们内控6σ范围=4，则%T=80%，对应的CPK=1.25，不良品率=175.8ppm

2、 实际的CPK=0.83，控制范围：±2.49σ，按6sigma理论则是5sigma。

3、 6sigma项目是指CPK2.0，公差带内需能容纳12σ（±6σ).