Método para aplicação de gráficos de controle de regressão no monitoramento de processos
Method for applying regression control charts to process monitoring
Pedrini, Danilo Cuzzuol; Caten, Carla Schwengber ten
http://dx.doi.org/10.1590/S0103-65132011005000001
Prod, vol.21, n1, p.106-117, 2011
Resumo
Este artigo propõe um método para a aplicação do gráfico de controle de regressão no monitoramento de processos industriais. Visando facilitar a aplicação do gráfico, o método é apresentado em duas fases: análise retrospectiva (Fase I) e monitoramento do processo (Fase II), além de incluir uma modificação do gráfico de controle de regressão múltipla, permitindo o monitoramento direto da característica de qualidade do processo ao invés do monitoramento dos resíduos padronizados do modelo. Também é proposto o gráfico de controle de extrapolação, que verifica se as variáveis de controle extrapolam o conjunto de valores utilizado para estimar o modelo de regressão. O método foi aplicado em um processo de uma indústria de borrachas. O desempenho do gráfico de controle foi avaliado pelo Número Médio de Amostras (NMA) até o sinal através do método de Monte Carlo, mostrando a eficiência do gráfico em detectar algumas modificações nos parâmetros do processo.
Palavras-chave
Gráfico de controle de regressão. Modelos de regressão linear. Número médio de amostras.
Abstract
This work proposes a method for the application of regression control charts in the monitoring of manufacturing processes. The proposed method is presented in two phases: retrospective analysis (Phase I) and process monitoring (Phase II). It includes a simple modification of the multiple regression control chart, allowing the monitoring of the values of quality characteristics of the process, instead of monitoring the regression standardized residuals. It also proposes an extrapolation control chart, which verifies whether the control variables extrapolate the set of data used in regression model estimation. The proposed method was successfully applied in a rubber manufacturing process. The Average Run Length (ARL) distribution was estimated using the Monte Carlo method, proving the efficiency of the proposed chart in detecting some alterations in process parameters.
Keywords
Regression control chart. Linear regression models. Average run length.
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