SPC Cpk alarms
Alarm triggers and reactions
In FactoryLogix, alarms consist of two parts: alarm triggers and alarm reactions.
An alarm trigger is a condition (usually material or quality related) that users or administrators want to be kept aware of or warned about when a particular threshold is reached. For example, you can set up an alarm trigger to warn a quality manager when the first-pass yield drops below a pre-determined level on the factory floor. Material related alarms might indicate when a tool's inter-service life has come to an end (that is, the device needs calibration). Additional alarm triggers can warn stock room personnel when materials are running low on the factory floor.
An alarm reaction is the resulting function that actually fires as a result of the trigger being satisfied or met.
Alarm reactions in FactoryLogix can consist of one or more of the following:
Email
SQL log
SQL statement
Line stop
DataMiner template
Alarm Reaction templates are created from the individual alarm reactions to be used in newly-created alarms. In the Alarm Reaction Template area, you can group multiple alarm reactions in each template to provide a wide variety of functionality.
An alarm trigger is the condition for which an alarm reaction should be executed. For example, quality managers might want to know when yield drops below a certain level in production to prevent it from dropping further. In this example, you would configure two levels of triggers for yield alarms for which users might configure different Alarm Reaction templates:
Set a warning threshold to send an email warning the appropriate personnel that a condition on the factory floor is starting to go out of its boundaries.
Set a threshold to not only send an email, but also send a line stop to an inForce unit to prevent more assemblies from being built incorrectly.
SPC Cpk alarm trigger type
You can set up SPC Cpk alarms in the Alarms area of the Analytics client application:
Cpk indicates whether or not the process being analyzed is capable of producing few or no defects—the higher the number, the less likely it will be that defects are produced.
The Cpk statistic is the minimum of the Cpl and Cpu statistics:
The Cpl statistic relates the difference between the center line and the Lower Specification Limit (LSL) to the standard deviation.
The Cpu statistic relates the difference between the Upper Specification Limit (USL) and the center line to the standard deviation.
When setting up a SPC Cpk alarm trigger, you select the workstation, the reactions that will fire alarm reaction templates, and specify the SPC options to be used for the Cpk alarm trigger.
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