请教高手，GRR测试问题

针对同一批产品，针对不同的尺寸，测试出来的GRR数值差异比较大？是何原因？
GRR数值从9.5%-27.9%
Part Name: MOP Plate, BID 59 Gauge Name: CMM Units of Measure: mm
Characteristic: 5.25 Lower Spec: -0.10 Upper Spec: 0.10

Inspector1 Inspector 2 Inspector 3 Inspector 4 Session 5 Session 6 Session 7
Part Rep 1 Rep 2 Rep 1 Rep 2 Rep 1 Rep 2 Rep 1 Rep 2 Rep 1 Rep 2 Rep 1 Rep 2 Rep 1 Rep 2
1 5.301 5.309 5.301 5.307 5.301 5.308 5.300 5.308
2 5.305 5.312 5.303 5.312 5.304 5.310 5.303 5.310
3 5.302 5.305 5.303 5.309 5.302 5.305 5.301 5.305
4 5.303 5.314 5.303 5.311 5.304 5.310 5.303 5.310
5 5.303 5.314 5.304 5.310 5.303 5.310 5.308 5.310
6 5.306 5.314 5.307 5.314 5.306 5.313 5.307 5.313
7 5.302 5.310 5.302 5.309 5.302 5.309 5.302 5.309
8 5.306 5.318 5.307 5.319 5.306 5.313 5.308 5.312
9 5.306 5.317 5.306 5.313 5.306 5.313 5.306 5.313
10 5.305 5.312 5.305 5.311 5.304 5.312 5.306 5.312
11
12
13
14
15



Repeatability (short-term inherent equipment variation) 0.005235229 1 sigma
Reproducibility (long-term, oper-to-oper, tool-to-tool, day-to-day variation) 0.000439628 1 sigma
Total gauge variation (from this study) 0.005253656 1 sigma
Material variation 0.002397735 1 sigma

13.5% P/T ratio Signal-to-noise ratio 0.46 SNR
(material sigma / measurement system sigma)