How do you know if a control chart is out of control?
The tests state that an out of control situation is present if one of the following conditions is true: 1) Seven points in a row above the average, 2) Seven points in a row below the average, 3) Seven points in a row trending up, or 4) Seven points in a row trending down.
What is an out of control process?
An out-of-control process has points falling outside the control limits or non-random patterns of points (called special-cause variation). If the process is in-control, no corrections or changes to the process are needed.
How do you control charts?
Basic Procedure
- Choose the appropriate control chart for your data.
- Determine the appropriate time period for collecting and plotting data.
- Collect data, construct your chart and analyze the data.
- Look for “out-of-control signals” on the control chart.
- Continue to plot data as they are generated.
What is LCL and UCL in control chart?
UCL = Upper Control Limit. LCL = Lower Control Limit.
How do we interpret control charts?
The following rules can be used to properly interpret control charts:
- Rule 1 – One point beyond the 3 σ control limit.
- Rule 2 – Eight or more points on one side of the centerline without crossing.
- Rule 3 – Four out of five points in zone B or beyond.
- Rule 4 – Six points or more in a row steadily increasing or decreasing.
What should you do if the process is out of control?
When there is an out of control point, it means that there is a special cause of variation present. All you have to do is to find the reason for the special cause and eliminate it from occurring again! As Dr. Deming would say: so simple.
What is out of control action plan?
The field reaction plan in the Control Plan is referring to what actions should be taken to correct the process and make sure incorrect products are reworked or rejected. A reaction plan is also often referred to as an out of control action plan (OCAP).