Roller die-cut in the ideal case, the linear speed of the cutting surface and bottom surface of the drum speed and speed of the corrugated board should be the same. But under the traditional roller die cutting, this will only exist for a short time, namely when the pad is not subject to wear, roller up and down motion of the theoretically 1:1 the same rate. But as the adhesive pads wear, end of the diameter of the drum will gradually decrease, which caused the end of roller surface velocity changes, eventually leading to carton length shortens. This phenomenon on a piece of cardboard to cut two or more cartons are particularly evident after a carton will cut shorter than the first. In practice, some business model long Second Edition do to compensate this difference in dimensions of the end. Roller pads at the end of auto repair equipment, and automatic compensation device of linear velocity can reduce this error.