Magnetic particle inspection: Status, advances, and challenges — Demands for automatic non-destructive testing

Magnetic particle inspection (MPI) is a highly sensitive and user-friendly nondestructive technique that remains essential for detecting surface and near-surface defects in ferromagnetic materials. Extensive research and industry applications have been conducted to verify its effectiveness. However, it is crucial to discuss the status of magnetic particle inspection, especially in light of advancements in image processing technology and the emergence of the concept of non-destructive testing 4.0. This review aims to explore automated magnetic particle inspection, focusing specifically on two key aspects: the factors influencing the formation of magnetic particle indications and the automatic recognition of these indications. The paper provides a comprehensive overview of current research, encompassing important aspects such as magnetic flux leakage, magnetic particles, image processing techniques, inspection devices and equipments. The challenges in implementing automatic magnetic particle inspection systems are also highlighted, such as the need for signal interpretation and noise reduction, reliable defect detection algorithms, system integration and real-time recognition. The paper concludes by summarizing the key findings and identifying future research directions in automatic non-destructive testing for magnetic particle inspection.