Automobile bumper is a safety device to absorb and slow down external impact and protect the front and rear parts of the car body. Many years ago, the front and rear bumpers of automobiles were stamped with steel plates into channel steel, riveted or welded with the longitudinal beam of the frame, and there was a big gap between them and the body, which looked very unsightly. With the development of automobile industry and the wide application of engineering plastics in automobile industry, automobile bumper, as an important safety device, has also gone to the road of innovation. Nowadays, in addition to maintaining the original protection function, the front and rear bumpers of automobiles should also pursue harmony and unity with body modeling and their own lightweight. The front and rear bumpers of cars are made of plastic, which is called plastic bumper.