Work orders represent a quantity of coils that will be tracked and processed as one entity within the Elgiloy plant. Several different customers may be included within one work order. Consequently, they may be shipped from the plant in several different batches to varying locations. Work orders are also grouped according to delivery time requirements and the sequence of processing steps required to complete them. The sequence of processing steps is comprised of sessions within the work order. However, one work order may require material to be handled at some processes more than once before completion. Fig. 3 represents a typical work order.
Step Process
1 Coil preparation line
2 Rolling mill
3 Coil preparation line
4 Vertical annealing furnace
5 Coil preparation line
6 Rolling mill
7 Coil preparation line
8 Vertical annealing furnace
9 Inspection line
In this example, the rolling mill and the annealing furnace required two sessions to be completed within the work order, while the coil preparation line was required four times. The session selection is based on process limits (such as draft in the rolling mill) as well as other scheduling rules according to product type.
The production planning system (PPS) utilizes a model created to represent the Elgiloy facility and its components. Elements within this model include:
· Machine (process steps) model.
· Resource model (finite capacity).
· Plant data.
· Machine constraints.
· Scheduling rules.
With an accurate representation of the Elgiloy plant and the existing customer order database, it is possible to create work orders which optimally schedule resources within the facility. All of the work orders created acknowledge the cost functions of the individual process steps and solve for the optimum configuration to maximize process utilization, while minimizing overall cost. In addition, these work orders are created to supply customer orders within the time specifications required.
Production scheduling and monitoring
After work orders have been created, they are transferred to the MSC system at the Elgiloy plant via ASCII file transfer. Applications within the MSC system receive the work order files and then execute Oracle® scripts to create all of the necessary database entries. Work orders may also be created manually using the work order scheduling system (WSS) described below in the event that the link to the enterprise system is inoperative.
As stated, work orders created by the PPS are designed to load the plant processes optimally, while supplying necessary customer orders in a timely fashion. The actual coils needed to allow one of these work orders to be completed are assigned at the plant via the work order scheduling system (WSS) located in the production office. Production office personnel are able to view the required work orders as well as the available inventory of coils using an MMI screen in the WSS system. Fig. 4 illustrates the work order to coil scheduling screen.
Coils needed to satisfy the work orders are then selected and associated with a particular work order. The required weight for the work order is displayed and decrements as each coil is assigned. The total weight assigned is displayed at the bottom of the screen. If a coil is assigned which causes the total work order weight to be exceeded then the amount of the surplus is designated as the "rest" weight.
The coils required to satisfy work orders created by the PPS task are 'shipped to the plant site in quantities and types sufficient to allow the work orders to be completed by production office personnel. They can be supplied from numerous sources; however, shipments are coordinated so that the pool of available inventory contains sufficient candidate coils to schedule work orders in the sequence and timeframe required by the PPS. As incoming coils are received, the primary data information (PDI) is entered on the Receiving Department NT workstation. As coils are handled throughout the facility, additional information is either manually entered by process operators or automatically acquired from process controllers during processing. These data are transferred to the appropriate tables within the central database. After completion of all processing, mechanical inspection is performed on the material, and the operator enters this information into the database. All process data and operator-entered information can then be queried and analyzed to study vendor performance, alloy process improvements and mechanical property refinements. In addition, utilizing a central database scheme allows the data acquired from all processing steps to be presented in reports that measure plant profitability, efficiency and process utilization. Critical data required by customers are gathered and can be presented with the shipped product. Process data serve as an historical record and are retained for several months within the database in the event they are required for review at a future time. After that time, data can be archived for longer-term storage.
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