ATTRIBUTES CONTROL CHARTS AS A TOOL OF RETROSPECTIVE ANALYSIS

1 JAROŠOVÁ Eva
Co-authors:
2 KLAPUT Pavel
Institutions:
1 SKODA AUTO University, Mladá Boleslav, Czech Republic, EU, jarosova@is.savs.cz
2 VSB - Technical University of Ostrava, Faculty of Metallurgy and Materials Engineering, Ostrava, Czech Republic, EU, pavel.klaput@vsb.cz
Conference:
27th International Conference on Metallurgy and Materials, Hotel Voronez I, Brno, Czech Republic, EU, May 23rd - 25th 2018
Proceedings:
Proceedings 27th International Conference on Metallurgy and Materials
Pages:
1818-1823
ISBN:
978-80-87294-84-0
ISSN:
2694-9296
Published:
24th October 2018
Proceedings of the conference were published in Web of Science and Scopus.
Metrics:
29 views / 7 downloads
Abstract

The paper deals with attributes control charts, especially with the control charts for fraction nonconforming, and their use in retrospective analysis of a process. Several forms of these charts are applied in a case study. The study concerns the occurrence of defects, especially the deformations on hot-rolled wire manufactured on the wire rod mill at Arcelor Mittal Ostrava a.s. Number of wire coils with defects is of interest. P charts are used to identify subgroups with an inflated fraction nonconforming that could distort results of evaluating differences in fraction nonconforming between steel grades, hot-rolling temperatures, and wire diameters. In addition, it is shown how to modify the traditional p chart in the case when a substantial part of the points fall outside control limits due to large subgroup sizes.

Keywords: Outliers, p chart, Laney’s chart, hot-rolled wire, deformations
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