Browsing by Author "Silva, Maria Isabel"
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- DMAIC implementation on catalytic converter production line: a case studyPublication . Silva, Maria Isabel; Vaz, Clara B.; Tulio, Paulo CezarThis thesis presents the application of the DMAIC methodology to improve the production process of a production line of catalytic converters in an automotive components company. This production line has been reporting non-compliance with customer demands within the normal working hours. The study was based on the five phases of the DMAIC methodology: Define, Measure, Analyze, Improve and Control. In the Define phase, the problem was identified and the characterization of the project specifications and its objectives was carried out. The Measure phase focused on representing the problem in a quantifiable way through measurements of the initial conditions of the line. The third phase involved analyzing the measured data in order to identify the main problem and assign its root causes. For the Improve phase, appropriate solutions were selected for each identified root cause. In the Control stage, a Gantt Chart was developed for the planning and implementation of improvements, documentation, training and monitoring and to validate the improvements that had already been implemented in terms of eliminating or reducing the problem. The results of the project involve each tool applied at each stage of the DMAIC, but it is important to emphasize that it will support the company with the application of simple, fast and inexpensive solutions that acted on the elimination root causes of the problem.
- Literature review for sample size analysis in time studiesPublication . Silva, Maria Isabel; Vaz, Clara B.In industrial context, it is important to act strategically and focus not only on daily challenges but also on the future ones. Hoshin Kanri is a methodology that builds a link between strategic and operational management. Problem identification and process understanding are key factors for this method, they can be facilitated through labor standards, which can be set through the time studies of a process. For a reliable study of time, it is necessary to define the task in study, divide it in measurement points, define how many times the task will be measured (sample size), measure the time and calculate the variance, average, maximum and minimum values. The determination of sample size is indispensable for an adequate study of time.
- Literature review for sample size analysis in time studiesPublication . Silva, Maria Isabel; Vaz, Clara B.An important method related to Lean strategies is Hoshin Kanri which combines operation and strategic management in order to solve both short and long-term problems in companies. Time studies are an effective way in order to apply this method. This paper regards to literature review in time studies of a process. In the literature review, two approaches of defining a sample size are presented: statistical analysis and conventional guide’s method, both currently used in some companies. Future analysis of the data collected in a company’s production line is devoted to verify whether or not the sample size is adequate, using both methods presented in this work.
- Sample size analysis for a production line study of timePublication . Silva, Maria Isabel; Vaz, Clara B.Setting labor standards is an important topic to operational and strategic planning which requires the time studies establishment. This paper applies the statistical method for the definition of a sample size in order to define a reliable cycle time for a real industrial process. For the case study it is considered a welding process performed by a single operator that does the load and unload of components in 4 di↵erent welding machines. In order to perform the time studies, it is necessary to collect continuously data in the production line by measuring the time taken for the operator to perform the task. In order to facilitate the measurements, the task is divided into small elements with visible start and end points, called Measurement Points, in which the measurement process is applied. Afterwards, the statistical method enables to determine the sample size of observations to calculate the reliable cycle time. For the welding process presented, it is stated that the sample size defined through the statistical method is 20. Thus, these time observations of the task are continuously collected in order to obtain a reliable cycle time for this welding process. This time study can be implemented in similar way in other industrial processes.