Hybrid sequence learning with interpretability for multi-class quality prediction in injection molding

Ensuring consistent quality in injection molding remains a critical challenge due to dynamic process variations and the limitations of traditional rule-based inspection methods. This study proposes a novel hybrid deep learning framework that integrates a Transformer encoder with a TabNet classifier...

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Main Authors: Varathorn Punyangarm, Supatchaya Chotayakul
Format: Article
Language:English
Published: Elsevier 2025-09-01
Series:Results in Engineering
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Online Access:http://www.sciencedirect.com/science/article/pii/S2590123025024788
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author Varathorn Punyangarm
Supatchaya Chotayakul
author_facet Varathorn Punyangarm
Supatchaya Chotayakul
author_sort Varathorn Punyangarm
collection DOAJ
description Ensuring consistent quality in injection molding remains a critical challenge due to dynamic process variations and the limitations of traditional rule-based inspection methods. This study proposes a novel hybrid deep learning framework that integrates a Transformer encoder with a TabNet classifier to enable interpretable, multi-class defect prediction using time-series part weight data. The Transformer module captures long-range temporal dependencies, while TabNet provides feature-level interpretability through sparse attention masks. The model was trained and validated on real-world data from over 30,000 injection cycles, covering five classes: acceptable part, short shot, flash, sink mark, and warpage. Evaluation results demonstrate that the proposed model significantly outperforms conventional machine learning methods such as Random Forest, XGBoost, CatBoost, and a hybrid deep learning baseline (CNN–TabNet), achieving a macro F1-score of 0.964 and a macro-averaged area under the receiver operating characteristic curve (AUROC) of 0.992. It also maintains high robustness under signal noise and supports inference within 100 milliseconds, enabling near real-time deployment (i.e., high-speed analysis of recent production windows). Importantly, the model offers actionable insights through built-in explainability mechanisms, helping operators understand and trace the root causes of predicted defects. This research contributes a scalable, low-cost, and interpretable solution for proactive quality monitoring, paving the way for practical adoption of explainable AI in smart manufacturing environments.
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spelling doaj-art-8438982b59c749b3a0ee110e739a8d352025-08-20T02:44:56ZengElsevierResults in Engineering2590-12302025-09-012710640810.1016/j.rineng.2025.106408Hybrid sequence learning with interpretability for multi-class quality prediction in injection moldingVarathorn Punyangarm0Supatchaya Chotayakul1Department of Industrial Engineering, Faculty of Engineering, Srinakharinwirot University, Ongkharak Campus, Nakhon Nayok 26120, ThailandCorresponding author.; Department of Industrial Engineering, Faculty of Engineering, Srinakharinwirot University, Ongkharak Campus, Nakhon Nayok 26120, ThailandEnsuring consistent quality in injection molding remains a critical challenge due to dynamic process variations and the limitations of traditional rule-based inspection methods. This study proposes a novel hybrid deep learning framework that integrates a Transformer encoder with a TabNet classifier to enable interpretable, multi-class defect prediction using time-series part weight data. The Transformer module captures long-range temporal dependencies, while TabNet provides feature-level interpretability through sparse attention masks. The model was trained and validated on real-world data from over 30,000 injection cycles, covering five classes: acceptable part, short shot, flash, sink mark, and warpage. Evaluation results demonstrate that the proposed model significantly outperforms conventional machine learning methods such as Random Forest, XGBoost, CatBoost, and a hybrid deep learning baseline (CNN–TabNet), achieving a macro F1-score of 0.964 and a macro-averaged area under the receiver operating characteristic curve (AUROC) of 0.992. It also maintains high robustness under signal noise and supports inference within 100 milliseconds, enabling near real-time deployment (i.e., high-speed analysis of recent production windows). Importantly, the model offers actionable insights through built-in explainability mechanisms, helping operators understand and trace the root causes of predicted defects. This research contributes a scalable, low-cost, and interpretable solution for proactive quality monitoring, paving the way for practical adoption of explainable AI in smart manufacturing environments.http://www.sciencedirect.com/science/article/pii/S2590123025024788Injection moldingDefect predictionTransformerTabnetExplainable AI
spellingShingle Varathorn Punyangarm
Supatchaya Chotayakul
Hybrid sequence learning with interpretability for multi-class quality prediction in injection molding
Results in Engineering
Injection molding
Defect prediction
Transformer
Tabnet
Explainable AI
title Hybrid sequence learning with interpretability for multi-class quality prediction in injection molding
title_full Hybrid sequence learning with interpretability for multi-class quality prediction in injection molding
title_fullStr Hybrid sequence learning with interpretability for multi-class quality prediction in injection molding
title_full_unstemmed Hybrid sequence learning with interpretability for multi-class quality prediction in injection molding
title_short Hybrid sequence learning with interpretability for multi-class quality prediction in injection molding
title_sort hybrid sequence learning with interpretability for multi class quality prediction in injection molding
topic Injection molding
Defect prediction
Transformer
Tabnet
Explainable AI
url http://www.sciencedirect.com/science/article/pii/S2590123025024788
work_keys_str_mv AT varathornpunyangarm hybridsequencelearningwithinterpretabilityformulticlassqualitypredictionininjectionmolding
AT supatchayachotayakul hybridsequencelearningwithinterpretabilityformulticlassqualitypredictionininjectionmolding