Main work of decoilers is to hold the coil stable and to give the metal sheet to system by decoiling with desired speed and amount. Decoilers are seperated to two main forms as mechanical decoiler and hydraulical decoilers. Logic behind the their calling type, is defined by the mechanism that tigthening and loosening the coil. For mechanical decoilers, a mechanical arm is used to tighten and loosen thecoild. As to hydraulic decoilers, they are designed with hydraulic system to ease coil tightening and loosening of heavy coils.