Cutting burs, also called rotary files, are small rotary tools with many cutting edges operating at very high speeds to remove material from a workpiece. The bur’s head contains the cutting edges, and the bur’s shank is inserted, like a drill bit, into a toolholder such as a drill chuck or collet. Burs come in many shapes, sizes, and end types, and they are used in a wide range of industries, including tool, die, and mold manufacturing, metal fabrication, dentistry, and woodworking. Burs are commonly used for welding preparation, finishing welded joints, deburring, chamfering, surface cleaning, and grinding down rough edges. A bur’s compact size gives the operator control over contact between the bur and the workpiece, making burs well suited for delicate operations. Burs can be used to remove small protrusions (burrs) that have formed on the surface of a workpiece as a result of a machining process.
Cutting burs come in a variety of shapes for specific applications, and include 14-degree taper, 60- and 90-degree cones, ball, cup, cone, cylindrical, inverted, oval, pear, sheet metal edging, thin disc, and tree burs.
The various cut types of cutting burs provide different rates of stock removal, and levels of finishing and control. Cut types include clog-resistant double cut, clog-resistant single cut, diamond cut, double cut, fine single cut, fine double cut, and single cut. There is also a variety of end cut types, which include End Cut, Plain End Burs, Point End, and Radius End.
Cutting burs are made of various materials, and come with a variety of finishes or coatings, each suitable for specific applications. Finishes or coatings may be applied to the head of the tool to improve wear resistance and to protect against high temperatures. Also consider the head and shank diameter, depending on the tool being used, and the size of the surface. Trade number is a number and letter used by cutting bur manufacturers to describe the size and shape of a bur. For example, an SM-1 bur is Shape M, and designates the bur is cone shaped, has a 1/2" length, and has a 1/4" head diameter. Trade number is defined by the International Organization for Standardization (ISO) 7755, which standardizes the names and sizes of cutting burs.