SPC Rules#
SPC rules are used to detect SPC violations. A Chart can have many SPC rules. An SPC rule tests a particular indicator for a specific pattern. It's also possible to specify for each Chart SPC rule an Exception Protocol to be opened and an action to be executed automatically whenever that SPC rule pattern is detected.
SPC rules can be system rules or user defined rules. The system rules are based on the Specification Limits as well as on the Nelson and Western Electric Rules and are described in the table below.
| Rule Name | Description |
|---|---|
| OutOfSpec | Any reading above the upper specification limit (if defined) or below the lower specification limit (if defined/) |
| Nelson1 | 1 of 1 point above +3 sigma or below -3 sigma (same as WesternElectric1/) |
| Nelson2 | 9 of 9 points on the same side of the centerline (similar to WesternElectric4 with 9 points instead of 8/) |
| Nelson3 | 6 consecutive increasing or decreasing points |
| Nelson4 | 14 consecutive alternating points |
| Nelson5 | 2 of 3 consecutive points above +2 sigma or below -2 sigma on the same side of the centerline (same as WesternElectric2/) |
| Nelson6 | 4 of 5 consecutive points above +1 sigma or below -1 sigma on the same side of the centerline (same as WesternElectric3/) |
| Nelson7 | 15 consecutive alternating points on either side of the centerline |
| Nelson8 | 8 consecutive points between +1 and -1 sigma on either side of the centerline |
| WesternElectric1 | 1 of 1 point above +3 sigma or below -3 sigma |
| WesternElectric2 | 2 of 3 consecutive points above +2 sigma or below -2 sigma on the same side of the centerline |
| WesternElectric3 | 4 of 5 consecutive points above +1 sigma or below -1 sigma on the same side of the centerline |
| WesternElectric4 | 8 of 8 points on the same side of the centerline |
Table: System SPC Rules
In addition to the system rules above, the following user defined rules are also available out of the box.
| Rule Name | Description |
|---|---|
| SPCHoldMaterial | 1.If there is no Material, the system will not process information. 2. Rule will look for the first Hold Reason in the Material step that is still not assigned to the Material. If no reason is found, the system will not process information. 3. The rule will put the Material on hold for the reason found in 2. |
| SPCPutEquipmentDown | 1. If there is no Resource, the system will not process information. 2. Rule will look for a Resource with State Model set to SEMI E10, and State set to Unscheduled Down. If no State Model exists or if no State Model State matches the Unscheduled Down SEMI E10 attribute, the system will not process information. 3. The rule will look for a transition from the current Resource state to the state found in 2. If it is found, it will perform a Resource State Change to the state found in 2, otherwise it will perform an Adjust State to the state found in 2. |
| SPCSendMail | 1. Rule will send an email to the distribution list defined in /Cmf/System/Configuration/Mail/LocalSupport/ with the following information:a) Subject b) Body 2. If a distribution list is not defined, the system will not process information. |
Table: User Defined SPC Rules
The applicability of an SPC rule to an Indicator as well as to a particular Chart or Chart Type is given by the ChartRuleScope Generic Table. By default the system ships with the configuration shown below.
| Rule | Indicator Scope | Scope Type | Chart Type | Chart | Rule Test Requirements |
|---|---|---|---|---|---|
| OutOfSpec | Indicator1 | All | The Upper or Lower Specification Limit is defined (rule will only test against the specification limits that are defined). | ||
| Nelson 1 | Indicator1And2 | All | The Upper or Lower Control Limit is defined (rule will only test against the control limits that are defined). | ||
| Nelson 2 | Indicator1And2 | All | The Centerline is defined. | ||
| Nelson 3 | Indicator1And2 | All | |||
| Nelson 4 | Indicator1And2 | All | |||
| Nelson 5 | Indicator1 | ChartType | Variable | The Centerline and Upper or Lower Control Limit are defined (rule will only test against the control limits that are defined). | |
| Nelson 6 | Indicator1 | ChartType | Variable | The Centerline and Upper or Lower Control Limit are defined (rule will only test against the control limits that are defined). | |
| Nelson 7 | Indicator1 | ChartType | Variable | The Centerline and Upper or Lower Control Limit are defined (rule will only test against the control limits that are defined). | |
| Nelson 8 | Indicator1 | ChartType | Variable | The Centerline and Upper or Lower Control Limit are defined (rule will only test against the control limits that are defined). | |
| Western Electric 1 | Indicator1And2 | All | The Upper or Lower Control Limit is defined (rule will only test against the control limits that are defined). | ||
| Western Electric 2 | Indicator1 | ChartType | Variable | The Centerline and Upper or Lower Control Limit are defined (rule will only test against the control limits that are defined). | |
| Western Electric 3 | Indicator1 | ChartType | Variable | The Centerline and Upper or Lower Control Limit are defined (rule will only test against the control limits that are defined). | |
| Western Electric 4 | Indicator1And2 | All | The Centerline is defined. |
Table: Default ChartRuleScope Generic Table configuration used for scope resolution
For further information on the applicability of these rules please consult the SPC Rules section in the SPC tutorial.
Available Pages#
Dive into the pages below to explore more about Spc Rules: