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Abstract(s)
Na presente dissertação de mestrado desenvolveu-se o tema “Utilização de ferramentas da qualidade na
melhoria do desempenho da produção de masterbatches” no âmbito do mestrado em Engenharia e Gestão
Industrial no Instituto Superior de Engenharia de Lisboa.
A realização deste trabalho teve como objetivo identificar as causas de ocorrência de lotes com cor não
conforme durante o fabrico de concentrados de cor em base polimérica – masterbatches (MB). Pretendeuse
também verificar se o processo de fabrico consegue cumprir com as especificações dos clientes, e
analisar as vantagens da utilização de cartas de controlo.
As ferramentas de controlo utilizadas foram aplicadas às coordenadas de cor do sistema CIE Lab, usadas
para quantificar a cor dos produtos.
Foram identificadas as causas de variação e de erro mais prováveis de ocorrer no processo produtivo e
representaram-se num diagrama de Ishikawa.
Através da análise de dados referentes aos lotes produzidos não conformes referentes aos anos de 2013,
2014 e 2020, verificou-se, através de um diagrama de Pareto, que as causas de falha mais frequentes foram
o scale up industrial dos produtos, mudanças associadas às matérias-primas utilizadas e contaminações
durante o processo de fabrico.
O controlo estatístico do processo foi aplicado a três produtos com um elevado número de lotes corrigidos
e com propriedades diferentes entre eles (polímero base, cor, composição e aplicação final).
Utilizaram-se cartas de Shewart (cartas de observações individuais e amplitudes móveis) para a
identificação e eliminação dos pontos fora de controlo estatístico e para o cálculo dos limites de controlo.
Analisou-se a capacidade de o processo cumprir as especificações dos clientes assim como a probabilidade
de serem produzidos lotes não conformes. Para dois dos produtos estudados, verificou-se que os intervalos
de especificação definidos pelos clientes são mais apertados do que a variabilidade natural do processo.
Desta forma é necessário implementar medidas que permitam diminuir a variabilidade e consequentemente
aumentar a capacidade do processo. Sugerem-se medidas para diminuir a variabilidade normal do processo,
como manter constante o tamanho dos lotes produzidos e o tipo de equipamento utilizado na produção dos
vários lotes.
Analisou-se para um quarto produto com um baixo número de dados a relevância das cartas de pré-controlo.
Verificou-se que são uma mais-valia para produtos com poucos dados.
Foi avaliada a relevância da utilização de cartas de controlo em futuras produções, tendo-se concluído que
a aplicação de cartas de controlo ao processo é uma mais-valia para a empresa, uma vez que permite detetar
produtos não conformes e distinguir as causas de variação normais das anormais.
In this master's thesis, the theme "Application of quality tools to optimize the production process of masterbatches" was developed within the scope of the Master's degree in Engineering and Industrial Management at the Instituto Superior de Engenharia de Lisboa. The objective of this work was to identify the causes of occurrence of lots with non-conforming color during the manufacture of color concentrates in polymeric base - masterbatches (MB). It was also intended to check whether the manufacturing process can comply with customer specifications, and to analyse the advantages of using control charts. The control tools used were applied to the color coordinates of the CIE Lab system, used to quantify the color of the products. The causes of variation and error most likely to occur in the production process were identified and were represented in an Ishikawa diagram. Through the analysis of data referring to non-conforming produced lots for the years 2013, 2014 and 2020, it was verified, through a Pareto diagram, that the most frequent causes of failure were the industrial scale up of the products, changes associated with the raw materials used and contamination during the manufacturing process. The statistical control of the process was applied to three products with a high number of corrected batches and with different properties between them (base polymer, color, composition, and final application). Shewart letters (individual observation charts and moving ranges) were used for the identification and elimination of points outside statistical control and for the calculation of control limits. The ability of the process to meet customer specifications as well as the probability of non-compliant batches to be produced was analyzed. For two of the products studied, it was found that the specification intervals defined by the customer are tighter than the natural variability of the process. In this way it is necessary to implement measures to reduce variability and consequently increase the capacity of the process. Measures are suggested to reduce the normal variability of the process, such as keeping constant the size of the lots produced and the type of equipment used in the production of the various lots. A fourth product with a low number of data was analyzed on the relevance of pre-control charts. It has been found that they are an asset for products with little data. The relevance of the use of control charts in future productions was assessed, and it was concluded that the application of control letters to the process is an added value for the company, since it allows the detecting of non-compliant products and distinguishing the causes of normal variation from abnormal ones.
In this master's thesis, the theme "Application of quality tools to optimize the production process of masterbatches" was developed within the scope of the Master's degree in Engineering and Industrial Management at the Instituto Superior de Engenharia de Lisboa. The objective of this work was to identify the causes of occurrence of lots with non-conforming color during the manufacture of color concentrates in polymeric base - masterbatches (MB). It was also intended to check whether the manufacturing process can comply with customer specifications, and to analyse the advantages of using control charts. The control tools used were applied to the color coordinates of the CIE Lab system, used to quantify the color of the products. The causes of variation and error most likely to occur in the production process were identified and were represented in an Ishikawa diagram. Through the analysis of data referring to non-conforming produced lots for the years 2013, 2014 and 2020, it was verified, through a Pareto diagram, that the most frequent causes of failure were the industrial scale up of the products, changes associated with the raw materials used and contamination during the manufacturing process. The statistical control of the process was applied to three products with a high number of corrected batches and with different properties between them (base polymer, color, composition, and final application). Shewart letters (individual observation charts and moving ranges) were used for the identification and elimination of points outside statistical control and for the calculation of control limits. The ability of the process to meet customer specifications as well as the probability of non-compliant batches to be produced was analyzed. For two of the products studied, it was found that the specification intervals defined by the customer are tighter than the natural variability of the process. In this way it is necessary to implement measures to reduce variability and consequently increase the capacity of the process. Measures are suggested to reduce the normal variability of the process, such as keeping constant the size of the lots produced and the type of equipment used in the production of the various lots. A fourth product with a low number of data was analyzed on the relevance of pre-control charts. It has been found that they are an asset for products with little data. The relevance of the use of control charts in future productions was assessed, and it was concluded that the application of control letters to the process is an added value for the company, since it allows the detecting of non-compliant products and distinguishing the causes of normal variation from abnormal ones.
Description
Trabalho Final de Mestrado para obtenção do grau de Mestre
em Engenharia e Gestão Industrial
Keywords
Qualidade Ferramentas da qualidade Masterbatch Cartas de controlo Causas normais Causas Anormais Especificações SPC Lotes não conformes Quality Quality tools Masterbatch Control charts Normal causes Abnormal causes Specifications Non-compliant batches
Citation
RAPOSO, Beatriz Silva Falcão Gonçalves – Utilização de ferramentas da qualidade na melhoria do desempenho da produção de masterbatches. Lisboa: Instituto Superior de Engenharia de Lisboa, 2021. Dissertação de Mestrado.
Publisher
Instituto Superior de Engenharia de Lisboa