Collect and Analyze Historical Data Timeline

The importance of a timeline is based on the fact that the process was running well for a certain period of time. In order for the process to become unstable, there has to be an identifiable change or changes that precipitated the process upset. The task is to identify these changes and correct them to get the process back in control. The timeline creation process starts during a period of process stability and ends some time after the process upsets were noticed. All events, even those remotely connected to the process, are listed on the timeline. Once the timeline is finished it becomes a helpful tool in identifying the event(s) that precipitated the problem. 

It should be noted that not all changes have an immediate effect on the process. In some cases, there can be a considerable incubation time before the effects of a change become noticeable. This, of course, complicates the troubleshooting process it is important to keep this in mind and not jump to conclusions. The author experienced a case where a disastrous wear problem was related to an event that took place four months earlier. The wear remained insignificant until about four months after a new feed housing was installed. However, when the rapid wear started, the screw was destroyed within a time period of only 48 hours. 

Replaced temperature sensor in water line, 03-16-00 Changed barrel temperature profile, 04-12-00 

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