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Statistical Process Control

In this section, you make the necessary preparations to use control charts.

In the Customizing application for control charts, you define:

• which charts will be available

• which function modules will be used to process the control charts

• how the charts will be assigned to the processes (SPC criteria)

Requirements

You can only use control charts for inspections in which planned inspection characteristics are used and measured values are recorded (that is, the indicators inspect with inspection plan or material specification and results recording based on characteristics are set in the material master, and the control indicator for measured value recording is set in the inspection characteristic).

• You define the SPC criteria in the inspection plan characteristic (that is, the assignment to the process).

• You define the control chart type in the sampling procedure.

When you plan the use of control charts, you must create sampling procedures with fixed samples. You can also use independent multiple samples or inspection points.

Further Notes

The following control chart types are supported:

• mean value chart with tolerances (acceptance chart)

• mean value chart without tolerances (Shewhart chart)

• standard deviation chart

You can combine a mean value chart and a standard deviation chart in a single control chart with two tracks.

You can call up and process the control chart for an inspection characteristic when you record results for an inspection characteristic.

A separate authorization object exists for the definition of the control limits. Refer to the chapter Environment/ authorizations for additional information.

You must use an appropriate

valuation rule when you evaluate the characteristic values on the basis of the control limits. Refer to the chapter Quality planning, Basic data, Sampling procedures, Valuation for additional information.

If the control limits are exceeded, the system creates a defect record or quality notification. Refer to the chapter Quality notifications, Defects recording for additional information.