IMPROVING EFFICIENCY OF ZINC COATING SECTION OF CONTINUOUS GALVANIZING PRODUCTION LINE USING QUALITY TOOLS

H Prashanth, Chitriki Thotappa

Abstract: Improving the efficiency of any system is a add value to the organization, especially in continuous production system. This paper aims at improving the efficiency of zinc coating section of continuous galvanizing line in a steel plant using QC tools.Galvanizing is a technique of smearing a protective Zinc coating on Steel or iron, to avert its rusting. The usual practice to produce galvanized steel is through hot dip galvanizing method. It is a continuous line where annealed sheet is immersed into molten Zn bath with Sink roll assembly guiding the sheet and air knife system maintaining proper coating of Zn onto the sheet and is passed through temper mill to impart required roughness on to it. Due to high vibration at sink roll assembly, sink roll bushes get wear frequently and scratches are formed on sheets, as a quality defect. The purpose of this paper is to identify the vibration causing element and minimize it, which reduces the sink roll changing frequency and increase Zn coating section availability time. And also minimizes the scratch formation on sheet during coating. Every Sink roll assembly changing takes four hours and complete line needs to be down, hampering the production. The data were collected, analyzed and implemented to increase the availability time of Zn coating section. Cause and effect analysis and Pareto analyses have been carried out and found that Corrector and Stabilizer roll shaft inclination found to be the root cause for high vibration high vibration by analyzing through Cause and Effect diagram and Pareto analysis, so same has been modified to non drive and sink roll bush thickness increased accordingly to get grater production cycle of sink roll.

Keywords: Corrector and Stabilizer roll, Cause and effect analysis, Dross formation, Hot dip galvanizing, Pareto analysis, Sink roll assembly vibration, Zinc coating

DOI: https://doi.org/10.15623/ijret.2017.0606013