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Quality  improvement of caster scheduling at Trinecke Zelezarny
  • Solodovnikov Vitaly
Solodovnikov Vitaly
National research university "Higher school of economics"
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Abstract

The paper analyzes melt shop and caster scheduling at special steel maker – Trinecke Zelezarny. The main optimization objectives for scheduling are formalized. The following key problems of scheduling are defined: underdeveloped optimization algorithms and insufficient computer performance. Based on this the key provisions of a new method of melt shop and caster scheduling are proposed. The method significantly improves quality of planning. It includes the following three stages: production capacity allocation; heat building; sequencing.  An experience of successful practical development and implementation of specialized software solution based on the new method at Czech special steel maker is provided.Abstract goes here. No heading necessary. The exporter will automatically turn this text before the first heading into an abstract.

Introduction

2008 crisis became an important  milestone for many metallurgical companies all around the world. It was a very  hard and fair test for survival. Companies which had effective and efficient  management process were able not only to keep their positions but find new  niches on the market. Companies which didn’t have it were faced with two  options: closing/selling assets or implementing significant improvements of  their supply chain management processes.
An analysis of successful  steelmakers at that time shows that the key element of their competitiveness  was improvement of order fulfillment process (Keey L., 2003; Konvicka D.,  Solodovnikov V. 2014), particular improvement of melt shop and caster  scheduling. The importance of having qualitative (realistic, balanced,  accurate) schedules is defined by several reasons.
First, melting and casting (blast furnace  production, steelmaking, and casting) are the place where the most value is  created in steel business. It is where raw materials are converted to steel. That  is why the biggest potential of efficiency and effectiveness improvement of steel  companies is located here.
Second, primary production sits at  the apex of an inverted “V” shaped manufacturing complex: from this point,  material flows through many different process routes with many manufacturing  steps.  The consequence is that the  profile of production at continuous casting ripples through the entire  downstream supply chain.  Customer  delivery performance, work-in-process and finished inventory levels, and even  prime yield performance is largely determined by the pattern of production at  continuous casting.
Third, primary production units (melting and  casting resources) are the most expensive manufacturing assets in the entire  steel supply chain, and have the highest operating costs. They are usually also  the bottleneck resources. Improved operating efficiency in this area can  significantly lower total enterprise manufacturing costs.
For all of these reasons, the efficiency  and effectiveness of melting, steelmaking and continuous casting management has  a profound effect on competitive advantages of a steel company and in most  aspects defines its financial performance. Permanently strengthening intensity of  competitive struggle of steel companies and rise of volatility on the ferrous  metals market define importance of development and implementation of new  approaches to solving a task of qualitative melt shop and caster scheduling.
The task of optimal melt shop and caster  scheduling is a NP kind problem.  In  fact, it is a combination of complex problems that has historically been  somewhat impervious to practical, optimized solutions. Often steel companies  with their partners tried by themselves to develop new methods of melt shop and  caster scheduling. Partners were scientific institutes and leading software vendors.  Most initiatives in the area of development of specialized solution independently  or in cooperation with partners have not brought desired results or fail despite  significant financial and labor investments. Main reasons for that were underdeveloped  optimization algorithms for the problem and insufficient computer processing  speeds. Recent advances in this area allowed LOGIS Research and Development  Laboratory specialists to develop a method and solution which let planners to  create qualitative melt shop and caster schedules to directly drive efficient  shop floor operations at large steel producers.

Experimental

The development of the new scheduling method and solution was based on data of Czech special steel maker – Trinecke Zelezarny.

Czech steel maker description

Trinecke Zelezarny is one of the leading producers in Europe. Its production assortment includes: wire rods, rebars, rails, flat products, seamless pipes, and sections. The company produces hundreds of steel grades. Its annual production is about 2.4 million tons. The staff is about 5 500 employees. The production supply chain of the company includes integrated facilities of iron and steel making. (see Figure 1).