What Happens Inside A Single Operation?
When a lot enters a new operation, what sort of activities are accomplished? Basically,
there are four types of transactions that occur within an operation. They are move
lot in, move lot out, track into a tool, and track out of a tool. See the diagram
below for how they are used. The movement transactions record lot movement, the
tracking transactions record equipment activity while working on one or more lots.
A description of each activity follows the diagram.
Activities Inside an Operation
Lot Move In:
When dispatching a lot into an operation, the actual transaction being performed
is a Lot Move In. This is an optional transaction and is only used if the operation
is set to track queue time between operations. Otherwise the Lot Move Out of the
previous operation is automatically considered to Move In to the current operation.
The dispatch screen shows the operator a list of lots that are waiting to enter
the operation and the status of all the tools in that operation for that production
line. The operator can select one or more lots to be dispatched and moves them into
the operation.
Track In:
In order to start a run on a tool, the operator needs to ‘track in’. The track-in
records the operator ID, the equipment ID, the lot ID and the date and time started.
This is done so proper cycle time can be measured for the run and to validate that
the setup on the tool is correct for that lot. If there is no equipment associated
with the operation, then no track in or track out is required.
Track Out:
Once the run is complete, the lot is tracked out of the tool. The track out completes
the run cycle and also records the operator, the equipment ID, the lot ID and the
date and time completed. It is on track-out that components and raw materials are
consumed and associated with the lots being processed. Losses are recorded at this
time and are categorized by loss code as defined in the Modeler tool and associated
with this operation. Operator activity and equipment activity times are based on
the difference between the track-in and the track-out time stamps. The track-out
also records the actual number of units processed. A running total of units processed
for the lot are compared to the move-in quantity for the lot to make sure that the
entire lot is complete before allowing the lot to move out to the next operation.
Retest quantities are also captured at this time.
Lot Move Out:
When the processing of all units in the lot is complete, the lot can be moved out
to the next operation. Often in the factory floor a quick visual inspection of the
parts is made at this point to guarantee that the desired processing actually took
place. For this reason, another opportunity is made to record losses. These losses
are tracked separately from the processing losses on track-out to enable reporting
opportunities. Once the lot is approved for move out, it exits the current operation
and moves to the next step in the workflow for the lot. At this move-out, any branching
logic in the workflow is evaluated to determine the next step. This is the only
required activity in the operation. In the simplest case, with no equipment tracking,
a workflow would consist of a series of move-outs.
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