PSImetals at ArcelorMittal Vega, Brazil

Automated line scheduling for a higher planning efficiency

To increase the productivity of the scheduling for several processing lines as well as to automatically consider economic and technical restrictions during scheduling in a standardised manner, ArcelorMittal decided for the implementation of the PSImetals Planning Line Scheduler.

Source: ArcelorMittal

The line scheduling of production lines from pickling and cold rolling to galvanising and batch annealing is now carried out more automated. The incorporationof PSImetals into the planning philosophy of ArcelorMittal Flat Carbon South America (FCSA) resulted in higher standardised planning processes.

The manufacturing of the hot rolled coils, delivered from ArcelorMittal Tubarão to ArcelorMittal Vega by ship, is characterized by the following processes. Via pickling the oxide layer from the surface of the hot-rolled coils is removed in a continuous process. Multiple strips are welded together and at the end of the pickling process, the edges of the strip steel are ground or cut to the specific sizes. Pickled coils are reduced in their thickness by cold rolling. After rolling, the coil can be treated in two different ways in accordance with the customer's requirements. By galvanising the coldrolled coils are coated with a fine zinc or iron-zinc layer to improve the steel's resistance to corrosion. Products which are not coated are batch annealed to restore the mechanical properties of the steel. Those products are finally skin pass rolled to correct the flatness and to adjust the desired roughness of the product.

Technical Challenges

The different production lines at ArcelorMittal Vega are very complex with certain technical restrictions including e.g. restrictions regarding the welding machine, the dimensions of the plant (deviations as to width, thickness and length), capacity of the ovens and others, which in turn create certain restrictions in the workflow. Furthermore product specifications reflect customer requirements, for example in terms of material type, surface quality and mechanical properties. To reconcile the plant restrictions with the customer requirements during scheduling, sequencing rules, socalled line programs, for each specific line are needed.

Former Scheduling Processes at Vega

The former programming of the production lines was made by spreadsheet processing in Excel with the help of the in-house production control system (GPAO). For that the information about the coils available for sequencing was imported from the GPAO database into Excel. Based on this data, the programmers manually sequence the materials taking account of the sequencing rules for each line. As there are no Excel system restrictions in connection with violation of the rules the programmers needed long-term experience to be able to create feasible line programs. After creation of the line programs, the programmer manually entered the data into the GPAO system: Coil by coil, in accordance with their sequence in Excel. Finally the GPAO system sent the line schedules to the level 2 systems as requirement for production. Both the manual sequencing and the manual data input were very time-consuming. As the entire understanding of the operating procedure was in the heads of the programmers this planning procedure was furthermore very error-prone and of minor productivity.

Targets & Project Methodology

The main objective of the project is the automation of the sequencing of ArcelorMittal Vega's production lines in the area of pickling/rolling, galvanising and batch annealing. With a new planning system based on the PSImetals Planning Line Scheduler the following targets shall be achieved:

  • Automatic observance of line specific and process-related restrictions during line programming (e. g.: widths, thicknesses, combination of materials based on quality and grade, maximal and minimal batch sizes for each order/each plant)
  • Enabling a priority-driven line scheduling with regard to efficiency, production and quality targets
  • Decision making support for the programmer regarding the identification of critical points (e. g. automatic warnings in case of rule violations)
  • Increase of the productivity of the production line sequencing team by an easier andfaster creation of line schedules, higher standardised processes and reduced manual interventions
  • Reduction of lead time, work in progress (WIP) and stock of finished products (FIP) as well as reduced scrapping
Plant-specific sequencing using the example of galvanisation
Plant-specific sequencing using the example of galvanisation. Source: AM Vega

The project was coordinated by the Integrated Design Process department with the involvement of ArcelorMittal Integrated Planning and Programming department and IT department. The project planning was managed using the DMADV method for the implementation of new products or processes (design for Six Sigma).

Realisation based on PSImetals

The PSImetals Planning Line Scheduler enables the scheduling of the production lines for different plants in metal production. Using PSImetals, the scheduler of ArcelorMittal Vega generate simulations and optimised lists of the materials to be processed for each line (cold rolling and pickling, galvanising 1 and 2, batch annealing) taking into account the specific sequencing rules per line. Internal software models reflect the rules and restrictions of production and assign evaluation criteria to them which act as weighting for their significance in the decision-making process. Thus it is possible to suggest an optimal sequence for the list of the coils to be produced.

For each line a specific system configuration was set up taking account of the specific characteristics:

  • Dimensions of the coils to be processed
  • Types of materials which the line can process
  • Physical restrictions of the plant
  • Operational regulations such as:

    • Priorities for delayed or premature orders (delay of X days or orders completed Y days prior)
    • Combination of coils that need to go through a subsequent process (e. g. Cutting of coil edges)
    • Combination of material types (e. g. production of materials with restrictions as to the surface quality before or after another type of material)

For the scheduling of the pickling and galvanising lines the user defines which line programme or which production section he wishes to simulate. PSImetals then provides an optimised sequence taking into account as many rules to be followed as possible. For the scheduling of the batch annealing line the planner defines the material quantity and the approximate number of batches to be produced. The system will then identify the best coil combinations.

For all lines PSImetals takes account of the technical and economic requirements and guides the scheduler in his decision-making. If rules or procedures are not complied, the system creates automatic warnings. Moreover, in a specific list view all critical rules are shown, which the sequencer has not complied with.

Various graphical user interfaces enable the user to analyse and change the list of the suggested coils if necessary:

  • View the quantity of planned materials.
  • View the quantity of materials available for programming.
  • Add, remove or exchange coils in simulations.
  • Define the production of one or several coils.
  • Create new simulations.

Once the planner has made all changes, he can release the schedules for processing.

The ArcelorMittal Vega plant is a flat carbon steel cold rolling, pickling and galvanising unit located at São Francisco do Sul, Brazil. Source: ArcelorMittal

Integration with the MES System

The production planning and control system GPAO (level 3) assumes the production control, location monitoring on yards and cranes as well material tracking including material planning, material control and quality monitoring. The system is integrated with the PSImetals Planning Line Scheduler as well as with the basic automation (Level 2) at ArcelorMittal Vega. PSImetals receives the coils available for planning from GPAO, optimises their sequence and sends back optimised line schedules. These schedules can be displayed and monitored as well as directly changed by the user in the GPAO system. The user can also change the production sequence of simulated materials or cancel it. Cancelled coils are then available for programming in PSImetals again.

Achieved results

With the implementation of the PSImetals Planning Line Scheduler the generation of line schedules was highly automated, systematised and standardised. By the fastened generation of lines schedules more time can be spent for the quality analysis of the programs itself. The reliability in respect of meeting the technical and economic plant requirements during schedule generation resulted in reduced scrapping and reduced WIP stocks. The increase of productivity of the programmers results also in improved control of the area's KPIs. The following productivity in scheduling time could be increased at the individual production lines:

Production line Increase*
Pickling/cold rolling 60%
Galvanising 1 50%
Galvanising 2 50%
Batch Annealing 66%**

* in scheduling time  ** estimated

These results were made possible only by the interaction between the IT department of process design and Information System Areas, Production programme planning and PSI Metals as software supplier. The use of the PSImetals Planning Line Scheduler at ArcelorMittal Vega and the application of the planning philosophy of ArcelorMittal Flat Carbon South America have contributed to the integration of the plants of Vega and Tubarão.