12th International Conference on Zinc & Zinc Alloy Coated Steel Sheet - GALVATECH 2021

The production of galvanized coils requires stable operating conditions for achieving sustainable product quality. In order to reach stable operation conditions for high quality products it is essential to prepare the production process according certain constraints. Those constraints include building schedules with a coffin shape ensuring that width and thickness changes are within certain limits, next to taking into account mechanical properties and surface requirements. The coffin shapes need to include smooth transitions in the production schedule to ensure that the transition of the furnace temperature between coils can be facilitated and that the service life for submerged equipment in the galvanizing bath can be extended. Furthermore, it needs to be taken care that the production orders are sorted in such a way that surface critical orders are scheduled first and high strength products in a second step. By clustering the product mix in batches and campaigns high line stability can be ensured. This scheduling strategy enables that roll wear is in-line with desired surface tolerance limits. For set-up purpose it is also essential to include into the schedule at specific positions production orders with low surface quality, e.g. prepare the right thermal cycle conditions and to clean polluted rolls and remove zinc dross and dust from zinc pot. Additionally, work roll type, roughness and type of post-treatment have to be considered for production scheduling at processing lines as well. The compilation of those schedules is a complex endeavor and pivotal for achieving sustainable production results. Software solutions can be used to build the schedules automatically according to stated constraints, allowing that schedules are being built with repeatable quality. However, the crucial element is to configure the scheduling software close to the optimal constraints as not only technical requirements need to be taken into consideration but also commercial constraints such as promised delivery times. This paper shows that it is a critical success factor to translate the available process know-how into rules when the scheduling system is being installed and fine-tuned. It needs to be taken care that the expert implementing the rules into the software solutions understands the requirement of the production to leverage the potential of the scheduling software to its full extent.