Week 7 Course Project Part 2 Tutorial
Note: This is a sample outline of how to proceed with this case. The data here are not the same as the data in your case. DO NOT USE THESE DATA in your case. This tutorial uses the template provide in the case. Most find using this template makes the completion of this case much easier.
1. A transmission manufacturing company has been having process difficulties at one its assembly stations. Thirty samples of four gears (n = 4) have been selected from the process and are provided below.
| | Observations |
Sample | 1 | 2 | 3 | 4 |
1 | | 4.92 | 4.26 | 4.94 | 4.29 |
2 | | 4.65 | 5.54 | 5 | 5.42 |
3 | | 5.77 ...view middle of the document...
4. Discuss notable out-of-control conditions displayed in the completed X-bar • R (average and range) control charts. Only consider points outside the control limits. Do not consider runs, set of points within certain zones, and so on.
5. If the conditions you note could be defined as assignable conditions and they are removed from the process, what will happen to the X-bar • R control chart?
(a) Remove the data related to the out-of-control points you observed from the original data and recalculate a new X-bar-bar, R-bar, and associated control limits.
(b) Create new X-bar • R (average and range) control charts from your updated data.
6. Discuss how the two sets of control charts are different. What has changed?
Calculate X-bar-bar, R-bar, and associated control limits using the data in the table above and create X-bar • R (average and range) control charts.
1. Using the template provided, click on the Data and Calculation tab. In the upper left corner, enter 30 for the number of samples and enter 4 for the sample size.
2. Enter the data into the yellow data area. Note: You will have to rotate your data to fit this table. When you are done you should have 30 observations (30 columns ), each with four results.
3. The template does all the calculations and plotting. The calculations are grouped into two parts, one for Averages (top group) and one for Ranges (bottom group). The X-bar-bar number we want in the top set of results titled Center. X-bar-bar = 5.057. The Center result the bottom set of data is R-bar. R-bar = 1.069.
3. Click on the X-bar Chart tab to view the X-bar chart; you should see a chart that looks like the one below. (It’s called an X-bar chart because you plot averages, or X-bars, on it.) We can see that one point, Point 22, is below the lower control limit (LCL).
4. Click on the R-Chart tab to view the R-chart and you should see a chart that looks like the one below. No points outside the control limits can be seen.
5. We now have enough information to answer Questions 1, 2, and 3 in the case study.