Process Capability (Six Sigma)
runningman1106
six_sigma.xlsxControl Chart (2)
| Objective: | |
| Your Black Belts developed the following data and created this control chart for sandwich preparation times. | |
| They say that the process is stable and shows that the average prep time is 1.7512 minutes and that | |
| individual prep times will not exceed 1.9205 minutes. They also say that it's very good because it shows very little variation. | |
| Instructions for you: | |
| Part I | |
| Do you agree with their interpretation? (see chart below) HINT: Use the 11 Shewhart Rules for Stability as the basis for your decision. | |
| Data: | |
| Current Sandwich Prep | |
| Times (in minutes) | |
| 1.6434 | |
| 1.8623 | |
| 1.7611 | |
| 1.7049 | |
| 1.7888 | |
| 1.7469 | |
| 1.8223 | |
| 1.7793 | |
| 1.7122 | |
| 1.7562 | |
| 1.6798 | |
| 1.7013 | |
| 1.7750 | |
| 1.7400 | |
| 1.8122 | |
| 1.7778 | |
| 1.7233 | |
| 1.7410 | |
| 1.7143 | |
| 1.7807 | |
| 19 | |
| Part II | |
| You and your team work to eliminate all known assignable causes from this process. You think you have | |
| accomplished this and collect the following data on the new process. Calculate the control chart center line | |
| and control limit values for an I-MR chart and use the 11 Shewhart Rules for Stability to determine if this process is now stable. | |
| Revised Process Prep | |
| Times (in minutes) | |
| 1.5364 | |
| 1.5892 | |
| 1.4823 | |
| 1.5610 | |
| 1.5468 | |
| 1.5021 | |
| 1.5065 | |
| 1.5002 | |
| 1.5501 | |
| 1.5423 | |
| 1.4322 | |
| 1.5732 | |
| 1.5923 | |
| 1.5567 | |
| 1.5022 | |
| 1.5345 | |
| 1.4822 | |
| 1.4922 | |
| 1.6004 | |
| 1.5178 | |
| AboveWay Sandwich, Inc. Customer Satisfaction Improvement | |
| Deliverable: | Control Chart |
| Student last name: | |
| If "NO", please identify BY NAME which of the 11 Shewhart Tests for Stability EACH chart fails. | I CHART: |
| Natural Pattern (stratefied) Only 25% outside of 1 SD Band Repeating pattern (4 up, 4 down, 4 up) | |
| MR CHART: | |
| Outlier: Moving range has one point out of Upper Control Limit Fails Natural Pattern Test (stratefied): Less than 1/3 outside of SD Band Repeat Pattern: 1 up 1 down 1 up 1 down | |
| INDIVIDUALS CHART: | |
| What did you get for a center line? | 1.5300 |
| What did you get for an upper control limit? | 1.6716 |
| What did you get for a lower control limit? | 1.3885 |
| MOVING RANGE CHART: | |
| What did you get for a center line? | 0.0532 |
| What did you get for an upper control limit? | 0.1739 |
| What did you get for a lower control limit? | 0.0000 |
| If "NO", please identify BY NAME which of the 11 Shewhart Tests for Stability EACH chart fails. | I CHART: |
| Natural Pattern (Borderline Stratified) Only 30% outside of 1 SD Band | |
| MR CHART: | |
| Natural Pattern Only 55% inside 1 SD Band | |
Process Capability (2)
| Objective: | ||
| Determine process capability | ||
| Instructions for you: | ||
| The company's goal is that every sandwich can be completed in less than 1.5 minutes. Based on the data | ||
| from the revised process control chart study, evaluate our shop's ability to meet this goal using the following | ||
| Evaluate our shop's ability to meet this goal using the following cabability measures. | ||
| Cp | ||
| Cpk | ||
| Pp | ||
| Ppk | ||
| z score | ||
| Sigma Level | ||
| % of sandwiches made within the 1.5 minute goal | ||
| PPM beyond the 1.5 minute goal | ||
| Data: See the revised data from the control chart tab. | ||
| AboveWay Sandwich, Inc. Customer Satisfaction Improvement | ||
| Deliverable: | Process Capability | |
| Student last name: | Your last name here | |
| What did you get for Cp? | Type here | Self check daniel-munson: Instructor: Hint: If you got a value, I would like to see it. |
| What did you get for Cpk? | Type here (use 2 decimal places) | Self check daniel-munson: Instructor: You should get a value between -2 and +2 |
| What, specifically, does this particular Cpk tell you about the process that other Cpk's may not? | Type here (use at most 25 words) | |
| What did you get for Pp? | Type here | Self check daniel-munson: Instructor: Hint: If you got a value, I would like to see it. |
| What did you get for Ppk? | Type here (use 2 decimal places) | Self check daniel-munson: Instructor: You should get a value between -3 and +3 |
| What did you get for Z-score? | Type here (use 2 decimal places) | Self check daniel-munson: Instructor: You should get a value between -2 to +2 |
| What does this Z-score mean? HINT: Use the z score you calculated in a sentence that explains what it tells you about this process. | Type here (use at most 25 words) | |
| Using the z score calculated above and a z table, estimate the % of sandwiches that will be made within the 1.5 minute goal. | Type here (use 2 decimal places) | Self check daniel-munson: Instructor: You should get a value <30% |
| PPM (aka DPMO) beyond the 1.5 minute goal | Type here | Self check daniel-munson: Instructor: You should have gotten a really big number. Also, this number should be "consistent" with the % within goal found above. |
191715131197531
1.9
1.8
1.7
1.6
Observation
I
n
d
i
v
i
d
u
a
l
V
a
l
u
e
_
X=1.7512
+3SL=1.9205
-3SL=1.5818
+2SL=1.8640
-2SL=1.6383
+1SL=1.8076
-1SL=1.6947
191715131197531
0.20
0.15
0.10
0.05
0.00
Observation
M
o
v
i
n
g
R
a
n
g
e
__
MR=0.0637
+3SL=0.2080
-3SL=0
+2SL=0.1599
-2SL=0
+1SL=0.1118
-1SL=0.0156
I-MR Chart for Current Sandwich Prep Times
