Creating SPC Calculations

You can quickly create SPC calculations using seven pre-configured calculations: Average, Profile, P-Chart, U-Chart, XBar-MR, XBar-R, and XBar-S. Based on the number of samples (subgroup size) you enter, Plant Applications automatically creates the child variables needed to perform the calculation.

NOTE: With Plant Applications, control limits can be automatically calculated as an option based on a configurable sample size. When available, calculated sigma values are reflected by control limits in SPC charts.

To create an SPC calculation

  1. In the Plant Applicationds Administrator, expand Plant Model, and create or select the variable you want to use for the calculation.

  2. Right-click the desired variable, point to Calculation and choose Create SPC Calculation. The SPC Calculation Configuration dialog box appears.

  3. Select a calculation type from the Calculation Type drop-down list.

  4. In the Subgroup size box, type the number of variables, which corresponds to the number of samples.

  5. In the Data Source box, select a data source from the list. The available data sources will be determined by the data sources you configured in the Data Source Types folder.

  6. In the Data Type box, select a data type from the list. The available data types will be determined by the data types you configured in the Data Types folder.

  7. optional: If you selected a user-defined data type, you can select a default failure value in the Default Failure box. The available values are those you created when you added a new data type.

  8. optional: If your data type is Float, type the number decimal places you want to use for the calculation.

  9. In the Event Type box, select either Production Event or Time. This determines what triggers the calculation to be run.

  10. optional: In the Specification box, click the Browse button and select a specification variable that you want to attach to all of the subgroup variables.

  11. optional: Click to select the All Samples Required check box. This will cause the calculation to fire only when all samples have been entered.

NOTE: This feature is set for each calculation type separately. For example, if the Average calculation requires all samples before calculation make sure to select the AVERAGE from the Calculation list and select the All Samples Required check box.

  1. Click Save.