UCL
Quality
UCL (Upper Control Limit)
Upper Control Limit
Statistically calculated upper boundary on a control chart representing expected common-cause variation.
Examples
- 01The UCL on the shaft diameter chart is 20.015 mm, calculated from three standard deviations above the process average.
- 02After the grinding wheel supplier is changed, the team recalculates the UCL from 25 new subgroups.
- 03When a point falls above the UCL, the operator stops, checks the last parts and records the cause on the chart.