The hardness of TPU is usually expressed by internationally recognized Shore hardness. Generally, it is used to represent the hardness below 100 degrees, such as 80A, 90A, 95A, 98A, etc., and D is used to represent the hardness above 100 degrees, such as 50D, 60D, 64D, 71D, 74D, etc. The function of injection molding is to process TPU into required parts, which is divided into