(1) Ndt Application in Automotive Industry -Ultrasound Testing of Automobile Half-axle
Fracture failure of half axle is mainly due to high frequency and low-stress fatigue damage, and the existence of internal defects of workpiece is one of the important reasons for fatigue fracture. Ultrasound can be used to inspect the raw materials of the semi-axle and the semi-finished products after forging.
When diagnosing, the high-frequency electric pulse is transformed into ultrasonic wave by a probe, and the coupling agent enters the half axis. When the incident wave encounters defects (i.e. heterogeneous interfaces), due to its different acoustic properties, the reflected beam will be transformed into high-frequency electric pulse through the probe. After amplification, the position, size and nature of the internal defects in the half-axis can be judged according to the position, amplitude and waveform characteristics of the reflected echo.
(2) Ndt Application in Automotive Industry-Detection of Surface Defects of Parts by Magnetic Powder Testing
Ferromagnetism and surface and near-surface defects of workpiece are displayed by focusing of magnetic powder. The magnetic particle testing technology is used in the inspection of most automobile parts such as crankshaft, camshaft, connecting rod, horizontal tie rod and ball head.
(3) Ndt Application in Automotive Industry-Laser Holographic Testing of Tires
Tire is a multi-layer structure made of rubber, curtain and nylon filament. Impurities are easily mixed in the overlap of the manufacturing process, resulting in defects such as bubbles and delamination. Conventional instruments are difficult to detect. It causes waste products to leave the factory and causes potential accidents.
Holographic technique is to record the specific light wave emitted by an object in the form of interference fringes by using the interference and diffraction principle of light. It is reproduced under certain conditions to form a realistic three-dimensional image of the object. The size of tire defect can be determined by abnormal distortion fringes of hologram, and the depth of tire defect can be determined by the spacing of abnormal fringes. Because the depth of the defect is proportional to the distance between the interference fringes, the deeper the defect is, the greater the distance between the defect and the tire inspection surface, the smaller the displacement reflected on the surface. The interference fringes formed in this way have larger spacing, and vice versa.