Centerline displays present an information-rich, easy-to-read tabular report of key process information. Statistics are calculated for the last several instances of a specific period of time or “run”, like an hour, grade run, or production day. These statistics are displayed alongside current values and control and/or spec limits. Tag limit integration causes values to change color when limit violations occur.
In general, there are two types of runs: process-dependent runs (which can vary in length like grade and product runs) and fixed runs (which do not vary in length, such as hours, shifts, and production days). Statistics can also be filtered based on process conditions, like when the process is completely down.
Centerlines use the Grade and Product labels by default, but they can be customized to use industry-specific terms, such as species, batch ID, product type, reel, roll, or any term that makes sense for the current application. Centerlines are either grade-based or non-grade-based. This depends on whether it makes sense to calculate statistics over the period of time a process was making a certain type of thing, in addition to over how long it takes to make individual things, or over fixed timespans. Grades mostly apply to continuous processes, where several instances of the same type of thing are made in succession, and then the process switches to making a different type of that thing, all without interruption. Grade-based centerlines can also filter other time periods by when a specific grade was produced.