1. Ultrasonic testing: When ultrasonic waves spread in the material to be tested, the acoustic properties and changes in the internal structure of the material have a certain impact on the spread of ultrasonic waves. By detecting the degree and situation of the impact of ultrasonic waves, we can understand the function and structure of the raw materials. 

2. Radiographic testing: Radiographic testing uses the difference in the amount of radiation transmitted through normal parts and defective parts to determine the blackness of the film.

3. Penetration testing: Penetration testing uses the capillary action of the liquid to penetrate the penetrating liquid into the open defects on the surface of the solid raw material, and then uses the imaging agent to suck the penetrating liquid out to the surface to reveal the existence of defects. Penetration testing is suitable for various metal and ceramic workpieces, and the time from penetration operation to defect manifestation is relatively short, usually about half an hour. It can detect surface fatigue, stress corrosion, and welding cracks, and can directly measure the size of cracks.

4. Magnetic particle testing: Magnetic particle testing uses magnetic flux leakage at defects to absorb magnetic particles and form magnetic traces to provide defect display. It can detect surface and sub-surface defects. The nature of the defect is easy to identify. Paint and electroplated surfaces will not affect the vividness of the detection.