Inspect the bolt surface and near-surface materials for minute defects such as cracks, folds, and inclusions caused by forging, machining, and heat treatment. The direction of these defects is mostly variable; therefore, flaw detection is required in all directions on the bolt surface.

1. A wet continuous method with composite magnetization and fluorescent magnetic particle testing is employed for continuous, uninterrupted, omnidirectional flaw detection of bolts.
2. 15/50D type test pieces are adhered to the workpiece surface. After composite magnetization, all grooves on the test piece should be clearly visible; cracks in the actual crack test piece should be clearly identifiable. The overall sensitivity of the flaw detector is verified as (qualified).
3. An imported programmable logic controller (PLC) is used for automatic or manual control of the equipment operation.
4. Considering the specific shape of the parts and the relevant requirements of the customer, a specific analysis is conducted to formulate a reasonable technical solution.

1. X-axis Magnetization: X-axis magnetization uses vertically arranged coils to establish a circumferential magnetic field on the surface of the part, detecting longitudinal discontinuities.
2. Y-axis Magnetization: Y-axis magnetization uses horizontally arranged coils to establish a longitudinal magnetic field on the surface of the part, detecting circumferential discontinuities.
3. Z-axis Magnetization: Z-axis magnetization uses front-to-back coils to establish opposing magnetic fields on the surface of the part, detecting opposing discontinuities.