Demerit control chart as a decision support tool in quality control of ductile cast-iron casting process

Abstract

Abstract. In many industrial areas the product quality can be unequivocally assigned to classes such as: "good", "bad" or "to repair". In case of casting processes, the product is approved to sales considering customer's requirements. Except for common characteristics, such as structure, compactness and mechanical properties, physical state of the product is also important. This state is assessed by checking occurrence of specific kind of defects. They are often conditionally accepted by a customer if they do not have any influence on functionality of the product (e.g. negative adhesive and cohesive phenomena, fatigue strength, thermal shocks). Authors' experience shows that current registering of the most frequently occurring defects and comparing them to customers' requirements can be very useful and help a quality engineer to control the casting process. They suggest using the Demerit Control Chart (DCC), according to authors' own methodology, in aspect of information about the castings accepted conditionally by a customer (DCC-recognition). DCC-recognition can be used to assess this quality by monitoring the value of just one aggregated measure for all kinds of defects instead of using a single attribute control chart for each of them. The test version of this tool considering severity of defects proved to be useful in one of the European foundries.

Carta de controle: uma revisão sistemática da literatura

“…No entanto, outros objetivos tem sido considerados, tais como detectar erros (ALBERS, 2012;ARFAN et al, 2020;CHARISTA et al, 2020;DENG et al, 2018;FLEGNER et al, 2020;JIN et al, 2020;LIAO et al, 2020;SANCHIS et al, 2018;SIKA et al, 2017); avaliar o desempenho (JIN et al, 2020); analisar a qualidade (KHAN et al, 2018;ZABIHINPOUR et al, 2014); analisar riscos (MEHMOOD et al, 2020); visualizar as tendências do processo (ROY et al, 2020); analisar não conformidades (BERK et al, 2019); e identificar eventos raros (NATHANSON et al, 2010).…”

“…A carta de controle é uma ferramenta básica do controle estatístico usada para detectar um sinal fora de controle no CEP com a exibição gráfica de uma característica de qualidade que foi medida ou calculada, e para acompanhar características de um processo ou produto por meio do monitoramento de mudanças estatísticas de uma amostra, retirada em intervalos de tempos definidos (FLEGNER et al, 2020;HASHIM et al, 2020;SIKA et al, 2017;ZABIHINPOUR et al, 2014).…”

Decision Support System in the Field of Defects Assessment in the Metal Matrix Composites Castings

“…The Polish Standard (PN-85/H-83105) also provides indicative causes of defects. In other studies [13,[53][54][55]57,59], which properly extend this standard, methods of detection of defects formed were also found.…”

“…All metal castings have defects of various types and origins. Any deviation in the characteristics, structure and mechanical or physicochemical properties of a material from the applicable requirements can be called a casting defect or defects [13,16,[48][49][50][51][52][53][54][55][56][57][58][59][60][61][62]. Defects can be identified based on their features, which in turn leads to the creation of the casting defect classification.…”

“…All the above-mentioned premises, as well as the development of the author's classification of casting defects based on the standard [64], which also takes defects of castings from metal composites into account, prompted the authors of the article to develop the Open Atlas of Casting Defects (OACD). It is a continuation of the authors' paper [1,54,55,[98][99][100] and ultimately aims to provide an open access platform for casting manufacturers, their customers and researchers involved in the assessment of casting defects and the origin of their formation. The open access formula will allow users to modify and complement data, and constantly update knowledge of castings and their defects.…”