5.0 Setting up the SI7500 (cont.)
502858 issue 1.1
5.0 Setting up the SI7500 (cont.)
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5.9.1 UCL & LCL Or Xbar & r UCL & LCL
The UCL and LCL fields are displayed when the subgroup size is 1 and the Xbar and r Ucl and Lcl fields are displayed
when the subgroup size is greater than 1.
By default, the UCL and LCL fields dis play the upper and lower (acceptance) limits specified ear lier on the Tolerance
setup screen. The limits are used by the SI7500 graphing soft ware to scale the value axis of SPC graphs.
CAUTION:
The UCL and LCL values shown on the SPC setup screen should not be altered after initial setup. Change them only if you are certain that your
application requires different values.
The Xbar Ucl and Xbar Lcl are the likely limits of the values of Xbar in future
subgroups. These lim its are either entered manually or calculated (Re calc
softkey) on the basis of existing subgroup data. The Xbar Ucl and Xbar Lcl values
are dis played as horizontal lines on the Xbar chart and used to generate SPC
limit alarms.
