Wan Azhari, Wan Noor Azrina (2026) Optimization in cooling variation of core and cavity temperatures for HDPE in injection moulding process. Doctoral thesis, Universiti Teknikal Malaysia Melaka.
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Optimization in cooling variation of core and cavity temperatures for HDPE in injection moulding process.pdf - Submitted Version Available under License Creative Commons Attribution. Download (3MB) |
Abstract
Plastic injection moulding is a widely used process for producing thermoplastic parts, yet warpage and shrinkage remain major challenges that compromise quality. This study employed a Box-Behnken Design with 17 experimental runs under the Response Surface Methodology (RSM) framework in Minitab to investigate the effects of core temperature, cavity temperature, and cooling time on five critical responses: warpage, volumetric shrinkage, ultimate tensile strength (UTS), Young’s modulus, and percentage elongation. The Analysis of Variance (ANOVA) confirmed that all three parameters significantly influenced the responses, with cavity temperature having the strongest effect on warpage, while core temperature dominated volumetric shrinkage, UTS, Young’s modulus, and elongation. Optimization results revealed that warpage could be reduced below 2.48 mm with lower core and cavity temperatures; volumetric shrinkage minimized to below 20.38% at a core temperature of 15 °C and cooling time of 12.5 s; UTS maximized above 19.52 N/mm² at 129.9 °C core temperature and 12.5 s cooling time; Young’s modulus improved beyond 4.91 N/mm² at 15 °C core temperature and 17.55 s cooling time; and % elongation enhanced above 91.79 mm at 15 °C for both core and cavity temperatures. Validation showed minimal percentage errors between experimental and model predictions where 2.40% (warpage), 0.02% (shrinkage), 0.85% (UTS), 0.48% (Young’s modulus), and 1.34% (elongation), confirming the robustness of the regression models. The real-world experimental validation using the optimal predicted value of 44°C, 15°C dan 37.5s, demonstrated a strong agreement between the predicted and experimental results, confirming that the developed quadratic regression models were statistically significant and capable of reliably representing the relationships between process parameters and responses. The minor deviations observed can be attributed to natural variations in machine performance, material behaviour, or environmental conditions during moulding. The importance of this study lies in its ability to tackle two of the most persistent defects in injection moulding of warpage and shrinkage while simultaneously improving the mechanical performance of HDPE parts. Beyond addressing these challenges, the study contributes to knowledge by establishing a robust multi-response optimization framework that highlights not only the main effects but also the interactions of core temperature, cavity temperature, and cooling time. This framework provides manufacturers with a practical tool for improving dimensional accuracy, enhancing mechanical reliability, reducing material waste, and increasing production efficiency, thereby bridging the gap between theoretical modelling and real-world manufacturing applications.
| Item Type: | Thesis (Doctoral) |
|---|---|
| Uncontrolled Keywords: | Injection moulding, Cooling variation, Mould temperature, Optimization process, HDPE |
| Subjects: | T Technology T Technology > TP Chemical technology |
| Divisions: | Library > Tesis > FTKIP |
| Depositing User: | Norhairol Khalid |
| Date Deposited: | 17 Mar 2026 07:14 |
| Last Modified: | 17 Mar 2026 07:14 |
| URI: | http://eprints.utem.edu.my/id/eprint/29649 |
| Statistic Details: | View Download Statistic |
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