U joint axle shaft: the connection between welding and NDT. Common welding defects can be divided into four categories: Weld size does not meet the requirements: such as welding seam super high, super wide.

Automobile steel is mainly divided into two categories: one is automobile body steel, which constitutes the shell and skeleton of the automobile：One is the alloy structural steel for automobile, which is the core material of automobile engine, transmission system and suspension system.

With the high-speed development of automobile, national defense, aviation, aerospace and other industries as well as the application of aluminum alloy and other new materials, the high-speed CNC machine tool processing requirements are higher and higher.