A compression coil spring is a mechanical component made by winding wire material into a spiral shape. It is characterized by elastically deforming, accumulating energy, and generating a repulsive force when subjected to a compressive load. Its applications are diverse, playing roles in shock absorption, generating repulsive force, and vibration absorption across a wide range of fields, including automotive suspensions, the operation of various valves, contact retention in switches, and positioning in precision equipment. The primary manufacturing method is generally cold working, where wire materials such as piano wire or hard steel wire are formed into a spiral shape using a coiling machine. After forming, heat treatment (annealing, tempering) is performed to stabilize spring characteristics and relieve stress. Furthermore, shot peening is carried out to improve durability, and surface treatments (plating, painting) are applied for rust prevention. The end faces may also be ground to enhance seating stability.