Shot Peening – Shot peening contains impacting the floor in the coiled spring by using a shot, modest spherical steel balls, glass, or ceramic debris. The goal of cooling is always to harden the coil’s metal and reduce the development of thermal and transformational gradients that would lead to cracking. https://rylanvpgex.shotblogs.com/details-fiction-and-types-of-coil-springs-41257489