Forging: It is the process of transforming a solid from one shape to another. Casting: It is the process of transforming a shapeless liquid metal into a solid with a shape. The so-called casting is the process of casting molten metal into a model to obtain a casting. The casting profession focuses on the metal melting process and the control of processes during the casting process. Forging is a plastic forming process in the solid state, which can be divided into hot processing and cold processing. Forgings include extrusion, drawing, roughening, punching, and so on. Casting is a solid liquid solid process, while forging is a solid to solid process where a solid can change its shape into another shape at high temperatures. There are still differences in the shape process and process of the two.

In the quality inspection of forgings, there are mainly external observation methods and internal inspection methods. The appearance method, as the name suggests, is to observe the appearance of the product, such as the shape, geometric dimensions, surface condition, etc. of the forging, in order to understand whether it meets the standards and whether there are external defects. Specifically, it is to check whether the external dimensions of the forging meet the specifications and whether there are defects on the surface, such as cracks, wrinkles, bubbles, indentations, pits, impurities, scratches, etc. on the surface of the forging. Internal testing mainly involves analyzing the chemical composition, macroscopic and microscopic structures, and mechanical properties of forgings. This inspection process requires the use of specialized instruments for high magnification inspection, with the aim of checking for any phenomena such as fractures and shrinkage within the forging, as well as defects such as dendrites and white spots, disordered flow lines, and throughflow. It also includes the tensile strength, ductility, hardness, plasticity, and heat resistance temperature of the forging.

The forging process of circular forgings mainly consists of the following processes: pier roughening, elongation, punching, and expanding. The difference between free forging and ring rolling processes is mainly in the process of expanding holes. In the production of ring forgings, free forging is usually used to expand the hole with a horse screw, while ring rolling is mainly used to expand the hole with rolling.