Control Chart Notice For Free

When points on a control chart move outside the upper or lower control limit, the process is said to be ?out of control.? As long as the points are within control limits, the process is ?in control.? But, what does an out of control process indicate? Many believe that an out of control process produces defective parts.

Statistical Process Control (SPC) Charts Rule 1 = Any point outside the control limits. Rule 2 = Seven consecutive points all above or all below the centre line, or all increasing or decreasing: Rule 3 = Unusual pattern or trends within the control limits:

Types of Control Charts X-Chart. X-Charts present variable data. ... P-Chart. P-Charts are used for data that is counted. ... NP-Chart. NP-Charts are used to present the number of nonconforming or conforming items. ... C-Chart. ... U-Chart. ... MR-Chart. ... Individual MR-Chart. ... Custom Data Control Chart.

The following rules can be used to properly interpret control charts: Rule 1 ? One point beyond the 3 ? 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.

All control charts have three basic components: a centerline, usually the mathematical average of all the samples plotted. upper and lower statistical control limits that define the constraints of common cause variations. performance data plotted over time.

If a data point falls outside the control limits, we assume that the process is probably out of control and that an investigation is warranted to find and eliminate the cause or causes.

A control chart displays process data by time, along with upper and lower control limits that delineate the expected range of variation for the process. These limits let you know when unusual variability occurs. Statistical formulas use historical records or sample data to calculate the control limits.