Small sample imbalanced die-casting product quality prediction based on fusion model

As the customization of new energy vehicles accelerates, the quality requirements for die-cast components are becoming increasingly stringent. Accurate and robust defect prediction has thus become critical for enhancing the competitiveness of manufacturing enterprises. In response to challenges such as small sample sizes, severe label imbalance, and strong inter-label correlations in die-casting quality prediction, this paper proposes CastMoE, a Casting-specific Mixture of Experts Framework for multi-label classification. CastMoE is designed to integrate multiple heterogeneous models with structurally diverse architectures through a Gated Mixture-of-Experts Fusion mechanism, which dynamically assigns label-wise softmax weights to adaptively aggregate predictions from different sub-models based on their performance. The framework incorporates a combination-based structure search strategy to explore and evaluate various model subsets, and selects the optimal fusion configuration based on cross-validated metrics. To ensure temporal consistency among variable-length time-series samples from the die-casting process, the Fast Dynamic Time Warping (FastDTW) algorithm is utilized. All sub-models and the fusion network are trained with Focal Loss to address class imbalance and improve the sensitivity to minority labels. During inference, a label-wise adaptive thresholding strategy is applied to convert probabilistic outputs into final binary decisions, with thresholds optimized using validation F1 scores to enhance recall and classification quality. Through the CastMoE framework, the optimal model combination identified by structure search consists of BiLSTM and CNN-LSTM-Attention. This configuration achieved a Micro-F1 score of 96.50% and a Micro-Recall of 95.83% under five-fold cross-validation, demonstrating the framework’s robustness, effectiveness, and industrial applicability for multi-label defect prediction in die-casting production.