This paper presents a hybrid fault-diagnosis framework for milling cutting tools designed to address three persistent challenges in industrial monitoring: noisy vibration signals, limited fault labels, and variability across operating conditions. The framework begins by removing baseline drift from raw signals to improve the signal-to-noise ratio. Logarithmic continuous wavelet scalograms are then constructed to provide precise time-frequency localization and reveal fault-related harmonics. To enhance feature clarity, a Canny edge operator is applied, suppressing minor artifacts and reducing intra-class variation so that key diagnostic structures are emphasized. Feature representation is obtained through a dual-branch encoder, where one pathway captures localized patterns while the other preserves long-range dependencies, resulting in compact and discriminative fault descriptors. These descriptors are integrated by an ensemble decision mechanism that assigns validation-guided weights to individual learners, ensuring reliable fault identification, improved robustness under noise, and stable performance across diverse operating conditions. Experimental validation on real-world cutting tool data demonstrates an accuracy of 99.78%, strong resilience to environmental noise, and consistent diagnostic performance under variable conditions. The framework remains lightweight, scalable, and readily deployable, providing a practical solution for high-precision tool fault diagnosis in data-constrained industrial environments.

A method is proposed for fault classification in milling machines using advanced image processing and machine learning. First, raw data are obtained from real-world industries, representing various fault types (tool, bearing, and gear faults) and normal conditions. These data are converted into two-dimensional continuous wavelet transform (CWT) images for superior time-frequency localization. The images are then augmented to increase dataset diversity using techniques such as rotating, scaling, and flipping. A contrast enhancement filter is applied to highlight key features, thereby improving the model’s learning and fault detection capability. The enhanced images are fed into a modified AlexNet model with three residual blocks to efficiently extract both spatial and temporal features from the CWT images. The modified AlexNet architecture is particularly well-suited to identifying complex patterns associated with different fault types. The deep features are optimized using ant colony optimization to reduce dimensionality while preserving relevant information, ensuring effective feature representation. These optimized features are then classified using a support vector machine, effectively distinguishing between fault types and normal conditions with high accuracy. The proposed method provides significant improvements in fault classification while outperforming state-of-the-art methods. It is thus a promising solution for industrial fault diagnosis and has potential for broader applications in predictive maintenance.

Underground petrochemical pipelines face severe risks from unreported third-party damage during excavation. Existing monitoring systems based on supervised deep learning or distributed acoustic sensing often require expensive hardware and large volumes of labeled defect data, and they exhibit high false-alarm rates in noisy urban environments. To overcome these limitations, this study proposes a cost-effective, field-feasible early warning framework utilizing attached acceleration sensors. High-frequency transient vibrations from physical impacts are demodulated into low-frequency rhythms using a Hilbert transform-based envelope algorithm, and these rhythms are then converted into 2D spectrograms via the Short-Time Fourier Transform. A 2D Convolutional Neural Network-Variational Autoencoder (2D CNN-VAE) is employed for unsupervised anomaly detection, trained specifically on normal background data. Furthermore, a hierarchical alarm classification logic is implemented to evaluate the reconstruction error, incorporating impulse noise rejection and temporal continuity checks. In a field demonstration, the proposed framework effectively suppressed false alarms caused by severe continuous noise, such as ground compacting, while reliably detecting sustained asphalt-breaking threats. This methodology demonstrates practical feasibility for isolating genuine excavation activities from transient environmental noise, offering a promising predictive maintenance approach that reduces alarm fatigue without requiring labeled defect data.