Once a work order is created it must be scheduled and released to the production line before work can begin. Scheduling can be done manually by the planner or accomplished automatically with an automated interface to an external planning system. The goal of the scheduling process is to assign the work order to a capacity group or sub-capacity group in the factory that owns the lot. The workflow can also be modified to one of the valid workflows for the production product. It is the workflow that will determine which sub-capacity groups will be utilized for the work order.

The planner selects one or more work orders from the list of pending work orders and assigns them to a particular work flow and capacity group. Once the work order is assigned to the capacity group, the utilization of that area is increased based on the product’s scheduling weight.

Scheduling Weight:
Each product is assigned a scheduling weight. The standard scheduling weight is ‘1’. Products that require less effort get a scheduling weight less than one and those that require work get a value that is more than one. The factory planner assigns these values. The number of units in the work order is multiplied by the scheduling weight and this value is added to the utilization of the capacity group. One operation is defined as the “bottleneck” operation. Once a work order or lot passes this operation, the utilization automatically drops to reflect the capacity that is again available in the area.

Bottleneck Operations:
For each capacity group or sub-capacity group one operation is flagged as the bottleneck operation. Work is planned to maximize the utilization of this bottleneck point. For assembly, this is typically the Wire-Bond operation. For Test it is typically Electrical Test. The intention is that once a work order or lot is beyond this operation, there is no longer a need to restrict placing more work orders into the line since they no longer require use of the scarce resource.

Releasing Work Orders to Production:
Once a work order is created and scheduled it can be released to production. This activity is typically performed by the production supervisor. A capacity group is selected and all pending work orders are shown for that area. The supervisor selects one or more of the work orders and identifies which production line is going to process them. Once assigned to a production line, the work orders typically will stay on that same line until they are complete. The supervisor releases them and they are moved from the lot start operation to the first step on their production workflow.