Abstract
Quality control is an important aspect in manufacturing process. The quality of product in injection moulding is influenced by injection moulding process parameter. In this study, the effect of injection moulding parameter on defects quantity of PET preform was investigated. Optimizing the parameter of injection moulding process is critical to enhance productivity where parameters must operate at an optimum level for an acceptable performance. Design of Experiment (DOE) by factorial design approach was used to find an optimum parameter setting and reduce the defects. In this case study, Minitab 17 software was used to analyses the data. The selected input parameters were mould hot runner temperature, water cooling chiller temperature 1 and water cooling chiller temperature 2. Meanwhile, the output for the process was defects quantity of the preform. The relationship between input and output of the process was analyzed using regression method and Analysis of Variance (ANOVA). In order to interpolate the experiment data, mathematical modeling was used which consists of different types of regression equation. Next, from the model, 95% confidence level (p-value) was considered and the significant parameter was figured out. This study involved a collaboration with a preform injection moulding company which was Nilai Legasi Plastik Sdn Bhd. The collaboration enabled the researchers to collect the data and also help the company to improve the quality of its production. The results of the study showed that the optimum parameter setting that could reduce the defect quantity of preform was MHR= 88°C, CT1= 24°C and CT2= 27°C. The comparison defect quantity analysis between current companies setting with the optimum setting showed improvement by 21% reduction of defect quantity at the optimum setting. Finally, from the optimization plot, the validation error between the prediction value and experiment was 1.72%. The result proved that quality of products can be improved by using the DOE approach.
Highlights
Plastic manufacturing has been one of the competitive markets which make producers to produce high quality parts at a low price and within the least time [1]
The results of the study showed that the optimum parameter setting that could reduce the defect quantity of preform was Mould hot runner controller (MHR)= 88°C, CT1= 24°C and Cooling Temperature 2 (CT2)= 27°C
The comparison defect quantity analysis between current companies setting with the optimum setting showed improvement by 21% reduction of defect quantity at the optimum setting
Summary
Plastic manufacturing has been one of the competitive markets which make producers to produce high quality parts at a low price and within the least time [1]. This study focused on the production of plastic PET preform which are produced in large volumes. A mandatory process involved in this production is injection moulding. Injection moulding is a standard method for producing parts in a large number and with high quality, value added commercial or industrial plastic parts in the market [2]. PET is one of the materials suitable to be used in plastic industries especially to make bottle preform [3]. The preforms produced using this material have some advantages such as impact resistant, very lightweight and non-toxic when in contact with food [4]
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