With this feature, you are now able to assign an uncertainty/guard band on your Measurement Parameters within your service levels.
To set an uncertainty/guard band on your Service Level, first you will access your Measurement Parameter under the Measurements tab in your Service Level.
Click ADMINISTRATION > Click "Service Levels" > Select the affected "Instrument Category" from the first drop down menu > Select the affected "Service Category" from the second drop down menu > Click the "Measurements" tab > Click the Measurement/Parameter name:
Your Measurement Parameter will pop-up. Next, click the "Display/Acceptance" tab. In the bottom right corner will be all of the options and settings for uncertainty/guard bands.
To access the "Uncertainty band:" drop down you will need to select the "Force guard bands (fail within uncertainty band)" check box.
Here you will see four formulas to assign to the "Uncertainty band" which all depend on the calculated Tool Uncertainty Ratio (TUR) value.
The NCSL Z540.3 requirement uses the following formula for determining the widths of the guard band where:
- A is the new tolerance limit
- T is the specification limit
- and the remainder of the formula is the actual width of the guard band:
Please note: The guard bands are only applied when TUR is less than 4:1.