Development of a performance model and its integration in an electro-galvanizing line

The performance of the electro-galvanizing line at Salzgitter Flachstahl GmbH was to be enhanced by activating additional plant reserves. This is often a difficult task because the individual plant components work very close to their design limits. Another difficulty in identifying plant reserves is the fact that the resource determining the plant speed frequently changes - especially with small lot sizes and high product variety. The importance of the ancillary plant components and accompanying factors, such as logistics and personnel, grows with increasing processing speeds. This is particularly true for strip treatment lines, as they are characterized by a strong interdependence between the process sections entry, treatment and exit and as a plant failure within the treatment section immediately translates into severe quality problems. At Salzgitter Flachstahl the performance of the electro-galvanizing line was raised by reducing the occurrence of erroneous manual entries. Manual entries had frequently been necessary in the past due to inadequate set-point calculations. This problem was solved using the operators' specialized knowledge. The first positive result of this measure was an increase in the share of automatic operation, with the consequent alleviation of the operating staff and a simultaneous rise in the average processing speed. A positive side effect was the adoption of a uniform operation mode across all shifts which improved overall process transparency. Based on the achieved intermediate stage, it is now possible to proceed with the optimization of the adjustment rules and the elimination of individual restrictions.