This provides a center wind right from the start, instead of requiring initial winding in surface mode after cutover.
Center winders have a large drive motor on the winding shaft and can easily reverse direction to wind coextruded or treated film with either side out or in.
They run faster and typically make larger diameter rolls than turret winders, but the diameter is still limited because all winding torque is applied from the center.
They use a small drive motor on a contact or winding drum and surface friction to wind film on a freely turning winding roll.
Surface winding can be combined with center assist, adding a drive motor to the winding roll to help wind slippery film.