Products and Solutions: Melt Shop Automation with PSImetals
Böhler Edelstahl, a leading producer of special steels and based in Kapfenberg Austria, is one of the pioneers in melt shop automation. The company starts to control their steel making processes in 1982 together with the German based soft-ware company PSI. Since 2004 Böhler Edelstahl works with the 3rd generation of the PSImetals melt shop information system. As a result of continuously standardizing and improving their steel making processes Böhler Edelstahl today is able to produce more than 300 steel grades and sets worldwide the benchmark in metallurgy.
The production of complex steel qualities requires a high degree of process control, precise operator control as well as immediate response to changes during production. The PSImetals based SIS (Steel plant Information System) supports melt shop operators in managing and controlling the entire production process in steel making.
Using four ASCII operator terminals and the very robust HP1000-F45 RTE real-time computer system first functionalities had been installed in 1982* to support and control the complex special steel production process with mainly focusing on costs and energy saving. It comprised the charge- and alloy calculation, electrical energy management to control the energy input per basket and heat as well as the communication with the laboratory to receive online analyses results.
After 10 years of successful operation the system was revamped and migrated to the DECnet Ethernet technology. That enabled to build a more integrated IT-Architecture including a direct link to SAP and the production planning system. At in total 32 workstations in the steel making plant the users were enabled to track production information as the latest inventory in scrap yard and alloy bunkers, to follow the heat tracking from scrap yard to casting as well as to control automatic acquired measured values online. Furthermore the system guided the operators by using standardized process instructions for each single process step in steel making for the first time.
In 2003 a new Level-2-automation system delivered within the commissioning of a new AOD-Converter as well as changing demands regarding quality management, process standardization, cost optimization as well as customer satisfaction and process traceability led to the decision to completely redesign the SIS. Due to the long term successful partnership between Böhler and PSI, PSImetals once again formed the basis for the 3rd generation of the SIS system. Today it forms the backbone of the entire IT-environment for steelmaking and integrates more than 30 individual lines with SAP ERP level, production planning and LIMS systems as well as basic automation and field level. More than 150 people are working with the system at more than 60 workplaces in the operator pulpits and in office workplaces in a 24x7 way.
Böhler maintains over 1600 steel grade standards with their individual chemical and mechanical quality properties. According to the technological manufacturing requirements of the steel grades, Process instructions are defined to exactly model the technological structure of the complete production process spanning all facilities. They summarize all production rules and information to be considered when producing a particular heat.
Modeling and structuring the production process using rule based and configurable process instructions resulted in significantly improvements of the knowledge base to automatically guide the operators. Harmonizing the production process, independent from the staff members and their individual experience, led to a more stable, reproducible process with less failure and improved products quality.
Right from the beginning Böhler focused on the optimization of material input for scrap and alloys. Today it is the most important and beneficial module and a powerful instrument for cost savings while producing this huge amount of various and very complex steel grades.
Improved algorithms in the 3rd generation consider more influencing parameters and different targets depending on material availability, subsequent production routes and treatment steps and provide the optimal combination of these parameters. Heat production costs could be saved directly.
The production preparation department creates a weekly master plan for heat demand based on customer orders and transmits this heat demand with daily updates to the SIS. Based on these heat demands the detailed heat scheduling and the elaboration of individual heat sequences are performed by the planner using the SIS for all facilities in steelmaking, special steelmaking and powder technology plant. The heat sequences are updated on a daily basis considering the current and forecasted facility availability, ladle and mould availability as well as chemical and technical restrictions of the heat follow up in one facility. The planner can create optimized heat sequences while minimizing violations of restrictions using rule based algorithms.
The production tracking component manages the heat status and progress during production from the feedstock material to the finished product through all facilities. All production, quality and cost relevant data for each heat are tracked; either automatically reported by Level-1 or Level-2 automation systems or manually entered by the operator. From these data automatically the start and stop of process steps is derived and the recalculation of the process instructions is triggered. Providing operator instructions like “take sample” the operator will be explicitly guided through the subsequent process steps. The Grafical user interfaces (GUI) and the operating philosophy for all operator screens are similar so that the staff can easily exchange their workplaces. The GUIs can easily be adapted to the needs of a special workplace or even role of an operator by a data dictionary driven configuration.
The equipment and ladle management includes the administration of operating resources, such as scrap baskets, steel ladles, moulds, etc., as well as facility parts, such as furnace lid, tundish, lances, etc. Equipment types and parts can be configured by the user. Status information (such as free, occupied, in repair, installed, etc.) provides a quick overview on the resources at all times. To monitor the „health status“ of a line all equipment events and states are tracked and traced on the basis of standard messages from the automation level and/or via manual operator input. The measured data provide a basis for statistical evaluations to decide whether repairs are necessary or not. A repair history shows any repair or maintenance work carried out, the time needed for repair work as well as further customer-specific data which may be necessary.
The Factory Model forms the heart of the SIS and models all objects for production planning, execution and quality control in a standardized manner. The integrated version control provides a change management especially for critical master data like steel grades, working plans, material data and process instructions. The Factory Model is an open data base model which can easily be adapted and enhanced by Böhler itself.
Using the factory model the level of automation could be increased incremental by a further integration of Level-1 and Level-2 systems using configurable unified standard messages. New automation systems or even new facilities can easily be “plugged in” by configuration and in most cases without further programming.
The Production Data Base serves as online information platform to keep all data for approximately one year. The Archive Data Base runs in parallel and keeps a copy of all data to serve as a long-term archive. The archive provides the input for further process improvements and research developments and serves as a preventive maintenance of facilities and equipment. An archiving process automatically transfers data into the archive and removes old data from the production data base. This method keeps the performance of the productive system in a good shape and allows time and performance consuming evaluations over a huge range of data.
The introduction of the Factory Model with the possibility to store and archive nearly unlimited amounts of data enables easier evaluation and research methods to better analyze and rate influencing parameters for quality and product improvement.
Since 30 years Böhler continuously invests in improving and enhancing the computer-aided melt shop automation. Based on the historical grown know-how of Böhler and standards like PSImetals the SIS successfully faces the complex tasks in special steel making being a powerful production management system.
The experiences made by Böhler served also as a pioneer for further PSImetals based steelmaking systems in the voestalpine group. The rule based process instructions formed the fundament for the CAQC-SM system in the LD-Steelmaking plant in Linz in 2006 and the implementation of the so-called MIS at Villares Metals S.A. in Sumare, Brazil in 2009.
Author: Ludwig Höbenreich, Böhler Edelstahl und Heinz-Josef Ponten, PSI Metals
* In 1982 the former BFI-BT, based in Düsseldorf and merged into PSI group in 1999, was contracted with this order.