Application of Statistics in Gauge Quantification
Statistics is used in many disciplines today for effective analysis of data. Among these fields include engineering where it is used for gauge quantification. For instance, it can be used to quantify uncertainties in a gauge study. In such a study, engineers gather the appropriate data based on the specific variable (s) being observed and estimate standard deviations for the various sources that contribute to uncertainty. They apply powerful statistical techniques to arrive at the most accurate solutions.
Attribute measurement analysis
Assuming a centered process what are the process control limits for the part
given USL = 0.95 in, LSL = 0.7 in
[email protected] = 0.0252 [email protected] = 0.0231
As we know for a centered process Xbar = (USL + LSL)/2 = 0.825 in
P_(pk ) = min( [USL - Xbar]/3*σ , [Xbar - LSL] / 3*σ ) = [USL - LSL] /6*σ
therefore σ = [0.95 - 0.7]/6*0.8
which gives σ = 0.05208 and total variance = σ = 0.05208
also d = [[email protected] + [email protected]] /2
therefore d = 0.02415
Now covering 99% of the variance
GRR = d/(5.15*TV)
which gives GRR = 0.02415/(5.15*0.05208)
= 0.09004 or 9%
process control limits
UCL =Xbar + 3*σ = 0.825 + 3*0.05208 = 0.98 in
LCL =Xbar - 3*σ = 0.825 - 3*0.05208 = 0.67 in
Assuming a centered process what are the process control limits for the part
given USL = 0.95 in, LSL = 0.7 in
[email protected] = 0.0252 [email protected] = 0.0231
As we know for a centered process Xbar = (USL + LSL)/2 = 0.825 in
P_(pk ) = min( [USL - Xbar]/3*σ , [Xbar - LSL] / 3*σ ) = [USL - LSL] /6*σ
therefore σ = [0.95 - 0.7]/6*1.3
which gives σ = 0.03205 and total variance = σ = 0.03205
also d = [[email protected] + [email protected]] /2
therefore d = 0.02415
Now covering 99% of the variance
GRR = d/(5.15*TV)
which gives GRR = 0.02415/(5.15*0.03205)
= 0.1463 or 14.63%
process control limits
UCL =Xbar + 3*σ = 0.825 + 3*0.03205 = 0.921 in
LCL =Xbar - 3*σ = 0.825 - 3*0.03205 = 0.73 in
Since the part is gaged by the ring gage for the maximum material condition, therefore,it's a go gage.
The diameter of the shaft =〖2.000〗_(-.005)^(+.008)in , range of diameter = 1.995 - 2.008 in
total tolerance = 0.013 in
generally gage tolerance is 10% of total tolerance therefore gage tolerance = 0.0013 in
for bilateral tolerance
we will divide gage tolerance by 2
we get 0.0013/2 = 0.00065 in
therefore size of go ring gage - 〖2.008〗_(-.00065)^(+.00065)
and the mean size of the ring gauge would be 2.008 in.
Part size | Number of acceptances in 20 measurements | |
2.004 | 20 | 1 |
2.0045 | 20 | 1 |
2.005 | 18 | 0.9 |
2.0055 | 13 | 0.65 |
2.006 | 8 | 0.4 |
2.0065 | 7 | 0.35 |
2.007 | 3 | 0.15 |
2.0085 | 1 | 0.05 |
2.009 | 0 | 0 |
2.0095 | 0 | 0 |
Part size | Number of acceptances in 20 measurements | Bias = reference size - measured size |
2.004 | 20 | 0.0040 |
2.0045 | 20 | 0.0045 |
2.005 | 18 | 0.0050 |
2.0055 | 13 | 0.0055 |
2.006 | 8 | 0.0060 |
2.0065 | 7 | 0.0065 |
2.007 | 3 | 0.0070 |
2.0085 | 1 | 0.0085 |
2.009 | 0 | 0.0090 |
2.0095 | 0 | 0.0095 |
No, more number of data would provide more accurate results.
Hypothesis testing
repeatability = variation due to measurement environment
therefore repeatability = 0.001921
To determine if the bias is significantly different from 0, we need to do a t test to test that
Null Hypothesis: Mean of bias is zero
Alternate Hypothesis: Mean of bias is not zero
We need to perform a two-tailed t test to test our hypothesis
Mean of bias= .00655
Sample SD = 0.001921
Degrees of freedom = n-1 = 9
Test value of t-statistic = (Mean of bias - 0)/(Sample SD/SQRT(10)) = 10.78
At a level of significance = 0.01 and df = 9, the critical values of t are 土3.2498
As the test value of t falls outside the range of critical values of t, we reject the null hypothesis
In conclusion, at 99% confidence, we can say that bias is not zero
To plot a gage performance curve we require following inputs
USL = 2.008, LSL = 1.995
Accuracy ( = -bias) = -0.00655 GRR(SD) = 0.001921
To get quality assistance with this topic, hire our hypothesis testing assignment help providers.
Gauge tolerance
given USL = 0.56 , LSL = 0.44
P_pk = 0.6
gage tolerance = 10% of part tolerance
Assuming a centered process
P_(pk ) = min( [USL - Xbar]/3*σ , [Xbar - LSL] / 3*σ ) = [USL - LSL] /6*σ
therefore σ = [0.56 - 0.44]/6*0.6
which gives σ = 0.0333
mean = 0.50
Agreement calculation between A and B
(heret represent agreement and f represent disagreement.)
part | Agreement (A/B)[1 or 0 by A] | Agreement (A/C) | Agreement (B/C) | Pass or fail (based on reference dimension (0.44-0.56) | part | Agreement (A/B) [1 or 0 by A] | Agreement (A/C) | Agreement (B/C) | Pass or fail (based on reference dimension (0.44-0.56) |
1 | t[1] | t | t | 1 | 8 | t[1] | t | t | 1 |
1 | t[1] | t | t | 1 | 8 | t[1] | t | t | 1 |
1 | t[1] | t | t | 1 | 8 | t[1] | t | t | 1 |
2 | t[0] | t | t | 0 | 9 | t[1] | t | t | 1 |
2 | t[0] | t | t | 0 | 9 | t[1] | t | t | 1 |
2 | t[0] | t | t | 0 | 9 | t[1] | t | t | 1 |
3 | t[0] | t | t | 0 | 10 | t[0] | t | t | 1 |
3 | t[0] | t | t | 0 | 10 | t[0] | f | f | 1 |
3 | t[0] | t | t | 0 | 10 | t[0] | t | t | 1 |
4 | t[0] | t | t | 0 | 11 | t[1] | t | t | 1 |
4 | t[0] | t | t | 0 | 11 | t[1] | t | t | 1 |
4 | t[0] | t | t | 0 | 11 | t[1] | t | t | 1 |
5 | t[1] | t | t | 1 | 12 | t[1] | t | t | 1 |
5 | t[1] | f | f | 1 | 12 | t[1] | f | f | 1 |
5 | t[0] | t | t | 1 | 12 | f[0] | t | f | 1 |
6 | t[1] | t | t | 1 | 13 | t[1] | t | t | 1 |
6 | t[1] | f | f | 1 | 13 | t[1] | t | t | 1 |
6 | t[1] | t | t | 1 | 13 | t[1] | t | t | 1 |
7 | t[1] | t | t | 1 | 14 | t[1] | t | t | 1 |
7 | t[1] | t | t | 1 | 14 | t[1] | t | t | 1 |
7 | t[1] | t | t | 1 | 14 | t[1] | t | t | 1 |
part | Agreement (A/B) [1 or 0 by A] | Agreement (A/C) | Agreement (B/C) | Pass or fail (based on reference dimension (0.44-0.56) | part | Agreement (A/B) [1 or 0 by A] | Agreement (A/C) | Agreement (B/C) | Pass or fail (based on reference dimension (0.44-0.56) |
15 | t[1] | t | t | 1 | 22 | t[1] | t | t | 1 |
15 | t[1] | t | t | 1 | 22 | t[1] | t | t | 1 |
15 | t[1] | t | t | 1 | 22 | t[1] | t | t | 1 |
16 | t[1] | t | t | 1 | 23 | t[0] | t | t | 1 |
16 | t[1] | t | t | 1 | 23 | f[1] | f | t | 1 |
16 | t[1] | t | t | 1 | 23 | t[0] | f | f | 1 |
17 | t[1] | t | t | 1 | 24 | t[1] | t | t | 1 |
17 | t[1] | t | t | 1 | 24 | t[1] | t | t | 1 |
17 | t[1] | t | t | 1 | 24 | t[1] | t | t | 1 |
18 | t[1] | t | t | 1 | 25 | t[1] | t | t | 1 |
18 | t[1] | t | t | 1 | 25 | t[1] | t | t | 1 |
18 | t[1] | t | t | 1 | 25 | t[1] | t | t | 1 |
19 | t[1] | f | f | 1 | 26 | t[1] | t | t | 1 |
19 | f[1] | t | f | 1 | 26 | t[1] | t | t | 1 |
19 | f[0] | t | f | 1 | 26 | t[1] | t | t | 1 |
20 | t[0] | f | f | 1 | 27 | t[0] | t | t | 0 |
20 | f[0] | f | t | 1 | 27 | t[0] | t | t | 0 |
20 | f[1] | f | t | 1 | 27 | f[0] | t | f | 0 |
21 | t[1] | t | t | 1 | 28 | t[1] | t | t | 1 |
21 | t[1] | t | t | 1 | 28 | t[1] | t | t | 1 |
21 | t[1] | t | t | 1 | 28 | t[1] | t | t | 1 |
part | Agreement (A/B) | Agreement (A/C) | Agreement (B/C) | Pass or fail (based on reference dimension (0.44-0.56) | part | Agreement (A/B) | Agreement (A/C) | Agreement (B/C) | Pass or fail (based on reference dimension (0.44-0.56) |
43 | t[1] | t | t | 1 | 45 | t[0] | t | t | 1 |
43 | t[1] | t | t | 1 | 45 | t[0] | t | t | 1 |
43 | t[1] | t | t | 1 | 45 | t[0] | t | t | 1 |
44 | t[0] | t | t | 0 | |||||
44 | t[0] | t | t | 0 | |||||
44 | t[0] | t | t | 0 |
operator | C | C | C | C | |||
1 | 1 | 0 | 0 | total | |||
actual count | expected | actual count | expected | ||||
A | 1 | actual count | 86 | 8 | 94 | ||
A | 1 | expected | 64.76 | 29.24 | 94 | ||
A | 0 | actual count | 7 | 34 | 41 | ||
A | 0 | expected | 28.24 | 12.76 | 41 | ||
total | 93 | 93 | 42 | 42 | 135 |
operator | C | C | C | C | |||
1 | 1 | 0 | 0 | total | |||
actual count | expected | actual count | expected | ||||
B | 1 | actual count | 88 | 9 | 97 | ||
B | 1 | expected | 66.82 | 30.18 | 97 | ||
B | 0 | actual count | 5 | 33 | 38 | ||
B | 0 | expected | 26.18 | 11.82 | 38 | ||
total | 93 | 93 | 42 | 42 | 135 |