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Historically, QMOS – Quad Mill Operation System - facilitated the scheduling of the rolling mill and melt shop through 3 different levels of scheduling:

• Scheduling the rolling mill based on sales requirements of finished good products
• Scheduling the caster, based on billets needed to fulfill FG products
• Scheduling heats necessary to fulfill various caster orders.

There are numerous complications with this 3-level scheduling practice for some schedulers. The complexity of the process and the disconnect between the caster and the melt shop orders make handling of off-spec heats, billets and in general the diversion process, very cumbersome.

Heat scheduling simplifies the scheduling process by reducing the scheduling layers to two. Rolling Mill scheduling based on finished goods is maintained, while scheduling caster and melt shop orders are combined into one. The demand for the melt shop is the caster work order or a given tonnage of billets with a specific size, grade and length. Based on this information, QMOS generates the heat line up when the scheduler decides to schedule the caster order, all in one screen,. The melt shop orders are maintained behind the scene. On the right hand side of the screen, caster work orders are shown, reflecting the appropriate tonnage, size and length and on the left hand side of the screen, scheduled heats can be viewed. By selecting a heat or a group of heats, their parent caster work order can easily be identified and heats can be removed or appended as need be. As long as a given heat is not in production, the scheduler is free to change the melt schedule or even choose to produce a certain percentage of a given caster order, leaving the rest to be fulfilled at a later time. The tonnage on the caster work order can easily be modified to accommodate last minute changes. Furthermore, heat scheduling allows for tracking of the tundish by grade. The user has the ability to view the number of heats made on each tundish and determine when the it should be changed.

From the quality control perspective, the main advantage of heat scheduling is the ease of diversion and reapplication. In the traditional practice of scheduling, the billets and heats have to be separately reapplied to a different grade upon production. With heat scheduling, by diverting a heat, the demand order for that heat which is the caster work order is also diverted, since the relationship is now closely integrated. In order to make the diversion process full-proof, test results of all the diverted heats along with their respective billets are compared against the specs of the new grade and both heats and billets are dispositioned accordingly.

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