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Attention percentages or attention factors express the amount of "attention" a machine operator must give to an operation on a particular machine. For most conventional machine shops this is almost always 100%, meaning that one operator's time must be fully devoted to the operation during the time it is being run. Therefore when creating a new operation on the routing for a work order, attention percentages always default to 100% for that operation. There are, however, manufacturing operations having long running processes that, once started, can run uninterrupted requiring nothing from a machine operator until perhaps when the operation is complete. Sometimes a single machine operator can setup and start several such operations so that work is being accomplished simultaneously on multiple machines. For example suppose we have a machine cell that requires operator attention only to remove each piece part from an operation when it is finished, and to load onto the machine each piece part that requires the operation. If the portion of the time required to perform this task amounts to 20% of the unit run time for each piece, an attention percent for this operation on this machine could reasonably be set to 20%. We have just considered the class of operations where attention percentages might be less than 100%. However there is another class of operations where attention factors greater than 100% might be required. A typical example involves an operation requiring the attention of two or more operators. "Hand" operations on certain very complex parts such as an assembly operation for a liquid rocket engine, a finishing operation for the wing or body "skin" of a large airliner, or one of the assembly operations for a satellite spacecraft. The Scheduler and Attention Percentages PROSPAC's scheduler is typically configured to express both machine capacity and manpower or crew capacity, and is therefore constrained by both since it is a finite capacity scheduler. When the scheduler schedules an operation considering both machine and crew capacities, the amount of machine capacity used is approximately equal to the setup time plus the unit run time times the work order quantity. However the amount of manpower capacity used is approximately equal to the amount of machine capacity used times the attention percentage. Manpower or crew capacity is handled in one of three ways:
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