Bolt inspection is divided into two types: manual and machine. Artificial is the most primitive and widely used method of consistent detection. In order to minimize the outflow of defective products, production enterprise personnel generally inspect the packaged or shipped products visually to eliminate defective products (including tooth damage, mixing, rust, etc.).
Another method is fully automatic machine inspection, mainly magnetic particle testing. Magnetic particle testing utilizes the interaction between the leakage magnetic field at bolt defects and the magnetic particle. In response to the difference in magnetic permeability between possible defects (such as cracks, slag inclusions, mixtures, etc.) in bolts and steel, the magnetic field at discontinuous areas of these materials will undergo distortion after magnetization, forming a leakage magnetic field on the surface of the workpiece at some magnetic flux leakage points, which attracts the magnetic particle to form a magnetic particle accumulation at the defect site - magnetic marks. Under appropriate lighting conditions, Displaying the location and shape of defects, observing and explaining the accumulation of these magnetic particles has achieved the goal of removing defective products.