Process and Production Monitoring
There are two primary types of monitoring windows within your system -- process and production. Production information is available for a specific machine or a group of machines. Process information is available for a specific machine. Both types of windows are accessible through the MONITOR menu.How a job is set up directly relates to the monitoring information available. The job parameter Schedule Now, for example, determines whether to monitor a job without reference to its machine's defined shift schedule. If this job parameter is set to "yes", the machine is monitored and job data is generated regardless of any idle periods in the shift. If this parameter is set to "no", the state of the Schedule Factory parameter determines when the machine is monitored.
The "Schedule Factory" job parameter indicates whether to use the factory shift schedule for the job. If this parameter is "yes", the job follows the defined shift schedule. If this parameter is set to "no", the job is considered to be idle and the associated machine is not monitored. If the "Schedule Now" parameter is "yes", this parameter is ignored.
Thus, these two job parameters affect how and when a job is monitored. How a machine is defined also affects the monitoring component of your system. Process variables and profile variables, if defined, have numerous windows devoted to reporting their behavior.
The following sections discuss some other job parameters and basic concepts that influence how information is monitored and presented within your system. A few of the more important types are discussed individually.
Production Monitoring
For production monitoring, there are two fundamental pieces of data -- pieces and time. Virtually all monitoring information involves or uses these two pieces of data to report on the progress and performance of a job.
Pieces
The first fundamental production monitoring quantity is pieces. Gross pieces are accumulated by counting closures of the primary contact. The standard multiplier is a parameter entered in the job's work order. It defines the maximum number of pieces produced per machine cycle for a job. The actual multiplier reports the number of pieces currently produced per machine cycle.
Reject pieces
Reject pieces are counted within your system to keep track of the number of good pieces. Rejects can be entered in one of three ways:
| · | by an operator at a keypad or EL/TS DCM,
|
| · | by a user at a work station,
|
| · | by automated equipment using contact inputs to the DCM.
|
|
|
Net parts counting is an alternate method of monitoring good parts. Using this method, finished boxes of good parts are counted instead of counting rejected parts. Any difference between the good parts counted and the gross pieces produced by the machine is automatically accumulated in the machine's designated reject reason. (The designated reason is defined from the Force Scrap flag on the Down Reason Sets window.) The number of good parts to be counted each time the net parts input contact is closed is tracked by the job parameter, net parts multiplier.
Time
The second fundamental production monitoring quantity is time. Production time is divided up into up time, down time and idle time. Down time is accumulated based upon cycle time exceeding the down time threshold. Pieces, possibly good pieces, can be produced while down time is accumulating. This depends upon how the down threshold and standard cycle time parameters are defined for a job. Down time quantities may be adjusted by a user at a work station.
Assist time is accumulated in parallel with production time. No assist time accumulates while a job is idle. Operators may call for assistance at any time by selecting one of the available assist reasons. This does not affect the production monitoring of the machine.
Process Monitoring
Process Variables
If defined for a machine, up to 50 process variables can be monitored. Most process variables are collected once per machine cycle. These types of process variables are used to monitor characteristics which are repeated with every machine cycle. Examples are pressure, temperature or time duration process variables.
Some process variables are collected only when new readings are provided by the operator. These types of process variables are used to monitor something which is sampled at irregular intervals. Examples are measurements of sampled parts such as weight or dimensions.
Whenever a reading is collected, it is compared to the process limits which have been defined for a job. If the reading is out of bounds, a process violation is flagged. This violation is displayed on the monitoring windows as a process exception.
Profiles
Up to 4 profiles can be monitored for each machine. Their behavior can be graphically displayed on any work station or at the relevant EL/TS DCM. A profile is a set of up to 500 readings of a single process input channel collected during one machine cycle. The input channel can be sampled as fast as once every 10 mS. Limits may be set for the minimum and maximum values (similar to process limits) to flag a process violation. Again, any violations are displayed on the monitoring windows.
Various values can be collected from a profile. These values can be read as process variables (called pseudo variables) for further tracking and limit checking.
SPC Data
DCMs calculate and monitor a variety of SPC parameters. X-bar and Range graphs display SPC alarms for defined process variables. On an EL/TS, the alarms are displayed to the right of the graph. The key for the alarms is as follows:
XCL The last X-bar value was not within control limits
RCL The last Range values was not within control limits
INC The last 8 X-bar values were continuously increasing
DEC The last 8 X-bar values were continuously decreasing
ABV The last 8 X-bar values were above the mean
BLW The last 8 X-bar values were below the mean
UTR The last 25 X-bar values show an upward trend
DTR The last 25 X-bar values show a downward trend
RSM Within the last 25 X-bar values, a RUNSUM exceeded 4.
If any of these parameters fall outside of accepted norms, an SPC violation is flagged on an EL/TS DCM. SPC subgroups can be collected for each process variable on a job-by-job basis. Monitor X-bar and Range charts are then provided in the monitoring windows for all current jobs. Historical X-Bar/Range charts can be displayed for completed jobs. Undefined and down cycle process readings are never included in SPC subgroups. SPC data can be transferred to the Extended SPC database for more advanced analysis.