the rotary cutting tool is used for making holes in walls of thermoplastic materials , e . g . fuel tanks produced by the blowing process . cutting blades pointing roughly in the axial direction are placed on the free end face of a circular , rotary tool member and said cutting blade score and displace , instead of cutting the material . the cutting blades are arranged at a drawing angle to the axial direction and slope to the inside or outside , depending on whether a burr is or is not required on the opening edge . a holding device in the form of a mandrel or pin ensures that the cut out circular disk does not drop into the container . thus , a cut is made , which is suitable for further processing by welding on connections or fitting seals and produces no chips and waste which could fall into the container .