Bolt Nut and Washer detection is divided into two types: manual and machine. Manual is the most primitive and most commonly used consistent detection method. In order to minimize the outflow of defective products, the general production company personnel inspect the packaged or shipped products by visual inspection to eliminate defective products (defects include tooth injuries, mixing, rust, etc.).
The other method is automatic machine inspection, mainly magnetic particle inspection. Magnetic particle inspection is based on the interaction between the leakage magnetic field and magnetic powder at the defect of Bolt Nut and Washer, aiming at the difference between the magnetic permeability of Bolt Nut and Washer (such as cracks, slag inclusions, mixing, etc.) and the magnetic permeability of steel. After magnetization, the magnetic field at the discontinuity of these materials will undergo turbulence, forming part of the magnetic flux leakage and generating a leakage magnetic field on the surface of the workpiece, thereby attracting the accumulation of magnetic powder at the defect of the magnetic powder-magnetic marks, which appear under proper light conditions. The defect location and shape, observation and explanation of the accumulation of these magnetic powders, has achieved the purpose of rejecting defective product.
