SPC Alarm Severity Maintenance

You use this activity to assign a message type to SPC trend rules for a site.

The system generates a message of the SPC Violation or SPC Warning type when conditions of an SPC trend rule are met. For more information, see Statistical Process Control (SPC).

Fields

The following tables describe fields requiring explanation:

AT&T Rules Tab Page

On this tab page you can maintain alarm severity records for AT&T trend rules used for X-Bar, Individual, and Median charts, and for R charts when the minimum subgroup is at least four (see SPC Chart Maintenance).

Field	Description
a	One point above the upper specification
b	One point below the lower specification
A	One point above the upper zone A (see SPC Chart Zones)
B	One point below the lower zone A
C	Two of three successive points in or above the upper zone A
D	Two of three successive points in or below the lower zone A
E	Four of five successive points in or above the upper zone B (see SPC Chart Zones)
F	Four of five successive points in or below the lower zone B
G	Eight successive points above the center line
H	Eight successive points below the center line
I	Fifteen successive points in zone C (see SPC Chart Zones)
J	Eight successive points on both sides of the center line
K	Fourteen successive points alternating up and down
L	Six successive points increasing or decreasing
Message Type	SPC Violation: Creates a message of the SPC_ALARM_VIOLATION type when the conditions for this trend rule are met. The message displays in red on the SPC Display activity screen. A violation has a higher priority than a warning. SPC Warning: Creates a message of the SPC_ALARM_WARNING type when the conditions for this trend rule are met. The message displays in yellow on the SPC Display activity screen. Ignore: Disables alarming for this trend rule.

Example Example

The following diagram illustrates these trend rules.

This graphic is explained in the accompanying text.

End of the example.

AT&T R Rules Tab Page

On this tab page you can maintain alarm severity records for AT&T R trend rules used for R charts when the minimum subgroup is less than four (see SPC Chart Maintenance).

Field	Description
a	One point above the upper specification
b	One point below the lower specification
A	One point above the upper zone A (see SPC Chart Zones)
B	Two successive points in or above the upper zone A
C	Three successive points in or above the upper zone B (see SPC Chart Zones)
D	Seven successive points in or above the upper zone C (see SPC Chart Zones)
E	Ten successive points in or below the lower zone C
F	Six successive points in or below the lower zone B
G	Four successive points in the lower zone A

AT&T A Rules Tab Page

On this tab page you can maintain alarm severity records for AT&T A trend rules used for P, NP, C, and U charts (see SPC Chart Maintenance).

Field	Description
a	One point above the upper specification
b	One point below the lower specification
A	One point above the upper zone A (see SPC Chart Zones)
B	Two successive points in or above the upper zone A
C	Three successive points in or above the upper zone B (see SPC Chart Zones)
D	Seven successive points in or above the upper zone C (see SPC Chart Zones)
E	Ten successive points in or below the lower zone C
F	Six successive points in or below the lower zone B
G	Four successive points in the lower zone A

Ford1 X Rules Tab Page

On this tab page you can maintain alarm severity records for Ford trend rules used for X-Bar charts (see SPC Chart Maintenance).

Field	Description
a	One point above the upper specification
b	One point below the lower specification
A	One point above the upper zone A (see SPC Chart Zones)
B	One point below the lower zone A
C	Seven points in a row above the center line
D	Seven points in a row below the center line
E	Seven points steadily increasing or decreasing
F	Fourteen points in a row alternating up and down
G	Two of three successive points in the upper zone A or beyond
H	Two of three successive points in the lower zone A or beyond

Ford1 R Rules Tab Page

On this tab page you can maintain alarm severity records for Ford trend rules used for R charts.

Field	Description
a	One point above the upper specification
b	One point below the lower specification
A	One point above the upper zone A (see SPC Chart Zones)
B	One point below the lower zone A
C	Fourteen points in a row alternating up and down

Sigma Rules Tab Page

On this tab page you can maintain alarm severity records for Sigma trend rules applied to S, Moving Average, and Moving Range charts.

Field	Description
a	One point above the upper specification
b	One point below the lower specification
A	One point above the upper zone A (see SPC Chart Zones)
B	One point below the lower zone A

Nelson Rules Tab Page

On this tab page you can maintain alarm severity records for Nelson's trend rules used for X-bar and S charts.

Field	Description
a	One point above the upper specification
b	One point below the lower specification
A	One point above the upper zone A (see SPC Chart Zones)
B	One point below the lower zone A
C	Nine points in a row in the upper zone C or beyond (see SPC Chart Zones)
D	Nine points in a row in the lower zone C or beyond
E	Six points in a row increasing or decreasing
F	Fourteen points in a row alternating up and down
G	Two of three points in a row in zone A or beyond
H	Four of five points in a row in zone B or beyond (see SPC Chart Zones)
I	Fifteen points in a row in zone C (above and below the center line)
J	Eight points on both sides of the center line with none in zone C

More Information

Statistical Process Control