Reliability HotWire

Issue 66, July 2006

Tool Tips

* How are confidence bounds handled in the Weibull++ 7 Function Wizard?
When using Weibull++ 7's Function Wizard to determine two-sided confidence bounds in a General Spreadsheet, it is important to remember that the confidence level falls between the confidence bounds. That is, in the case of two-sided confidence bounds, a 90% confidence level is that area between 5% (the lower confidence bound) and 95% (the upper confidence bound), as shown next.


Thus, to obtain both bounds, you must use the function twice.

For example, if you want cell A2 to display reliability at a particular time and you want cells A1 and A3 to display upper and lower confidence bounds respectively with a confidence level of 90%, you would use the RELIABILITY function for all three cells. Cell A2 would be calculated leaving the Confidence Level field blank.

Cell A1 would be calculated with a value of 0.95 in the Confidence Level field.

 

Cell A3 would be calculated with a value of 0.05 in the Confidence Level field. All other inputs would remain the same for all three cells.

* How can RCM++ and Xfmea phrase sets be created or edited?
The Phrase Set Properties window, accessed from the Profiles/Libraries Management window, allows you to add or edit a phrase set, as shown next.

Both RCM++ and Xfmea also allow you to import and export phrases from Excel. This allows you to export the current phrase sets to Excel, edit them and then import them back into RCM++ or Xfmea. For large editing projects, you may find this faster than working in the Phrase Set Properties window. It also allows you to add phrase sets that have been defined in other applications that can be transferred to Excel and then imported into RCM++ or Xfmea.

To export phrases, open the Phrase Sets Properties window and open the page that you want to export the phrases from (e.g. the Function page). Click Export to Excel. In the window that appears, type the filename in the input box and click Save to start the process. When the export is complete, the new spreadsheet with the phrases will be opened automatically in Microsoft Excel, as long as the application is installed on your computer.

When importing phrases from Excel, they must be located in the first column of the first worksheet, starting with the first row. To import phrases, open the Phrase Sets Properties window and open the page that you want to import the phrases into (e.g. the Function page). Click Import from Excel. In the window that appears, select an Excel file (*.xls) to import the phrase sets from and click Open.

You can also export the descriptions from an existing FMEA to a new phrase set or an existing phrase set. From the FMEA, select Import/Export Items FMEA and then either Export to New Phrase Set or Export to Existing Phrase Set from the System Hierarchy menu in the Project window. If you are exporting the descriptions as a new phrase set, you will see a window that allows you to enter a name and a description for the new phrase set. If you are exporting the descriptions to an existing phrase set, you will see a window that allows you to choose the phrase set you want to add to. Please note that this functionality adds only unique phrase sets. For example, if the existing phrase set contains a failure cause called "Excessive condensation" and so does the FMEA analysis that is being exported, the phrase will not be duplicated.

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