AUTHORS: N. Carvalho, A. Correia, F. De Almeida
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ABSTRACT: In the aluminium industry, the chain of processes is long and involves different operations, starting with operations related to the extractive industry and ending with the piece of aluminium that would be sold. To make this process solid, viable and competitive, companies involved need to base their decisions on a consistent set of data, which enables them to obtain workable information throughout the process and thereby reduce, or eliminate, the percentage of defects that occur. During the aluminium extrusion, defects are largely responsible for decreasing the quality of the finished product (profiles) which requires the duplication of work. Thus, defects lead to increased production costs, delays in delivery and increase of the scrap percentage. This work, resorting data previously collected in an industry in this area, aims to classify and quantify the defects that occur throughout the extrusion process. To identify the causes, to correct possible deviations, to find solutions and improvements are used several quality tools in particular: Brainstorming, Pareto Diagram, Ishikawa Diagram, Histogram and Control Chart. Above all, the purpose of using these tools is to provide operators and managers with adequate indicators, which allow the control of the production process and the identification of critical extrusion variables or others, responsible for excess waste, defects and, consequently, in order to increase productivity. During the execution of this work, the defects of the extrusion process were typified and quantified, and whose causes and possible corrective actions were studied. Through the obtained results, it is clear that the 'bubble' defect represents a very significant part of the total defects studied, which revealed the pertinence of the monitoring of this defect. During the study we conclude that there are several variables, which affect the appearance of the 'bubble' defect. Then, some control charts of the main variables are performed, in particular for the time at the maximum extrusion pressure and the temperature of the container.
KEYWORDS: Extrusion, Aluminium, Statistical Process Control, Quality Control
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