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Sequence Type
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Sequence Type
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The sequence type is used to structure how you want the operations to flow material in your job. It establishes the flow rules that the DMS Scheduling Engine can follow. Sequence types are given at the job level and may be changed at the operation level.
Sequence Types available are:
Sequential:
The next operation can not start until the preceding operation has been fully completed.
Parallel:
Operations can optionally run at the same time with no dependence on one another.
Operations can overlap by passing a user defined quantity from one operation to next. Note: in the case of where there may be a faster running operation downstream that resource may sit idle waiting for parts from the previous resource. The idle time is not shown in the operation setup or runtime, but does take up capacity on the resource. For example, if 10 parts are being manufactured where the lots size is 1, the first operation takes 2 hours per part, and the second operation takes 1 hour per part, the following load takes place:
Seq Op Id Operation time Resource Load
1 10 20 hours 20 hours
2 20 10 hours 19 hours **
** Operation 20 can start 2 hours after operation 10, but because it is faster it has to site idle and wait for the next part to be passed from operation 10. The load on the resource for operation 20 would then be 20 hours - 2 hours at the start to wait for the first part, plus 1 hours of end of operation 10 to process the last part as operation 20 takes 1 hours per part.
Lot Optimum:
Is similar to Lot in that operations can overlap by passing a user defined quantity from one operation to next but with Lot Optimum if a downstream operation is faster the DMS scheduling engine with automatically adjust the flow to compensate so the resource is not scheduled to sit idle waiting for parts from the previous resource. Lot Optimum will reduce the total load on individual resources, but may result in a later schedule completion date because of local efficiency instead of global efficiencies.
Overlap:
Is similar to Lot but overlap is based on a percentage of time (hours) and not quantity. The next operation will not start until the current operation has completed its percentage of time (Percentage Overlap).
Overlap Optimum:
Is similar to the Overlap operations and is based on a percentage of time (hours) to complete before the next operation can start (Percentage Overlap). Overlap Optimum makes sure that the current operation does not end before its predecessor.
Is similar sequential, but uses a project management name and can have an hour amount h so that queue time can be added between operations. For example, Finish to Start 3 would mean that 3 hours of working queue time (measured by the operation’s resource) would be added between operations.
Is similar to sequential, but the next operation starts on the next available working shift.
Finish to Start Next Day:
Is similar to sequential, but the next operation starts on the next available working day.
Finish to Finish:
Is used when the next operation can not finish until the previous operation is complete.
Start to Start:
Is used when the next operation can not start unless the previous operation has started. Start to Start can have an hour amount h so that queue time can be added between operations. For example, Start to Start 5 would mean that 5 hours of working queue time (measured by the operation’s resource) would be added before the next operation can start.
Operation Level Sequence Types
