CARBIDE BURR SELECTION AND USE
Burrs are sometimes referred to as rotary files and come in many shapes and sizes. Typical applications are weld preparation, weld smoothing, deburing, chamfering, deflashing, and scale removal. Burs are typically chucked in air driven die grinders and used in hand operations.
The first step in selecting the proper burr is to pick the best shape and cut style.
- Selection of shape and diameter should be based on the work piece, and the operation to be performed.
- Burs come in 10 basic shapes: Cylindrical, Cylindrical Ball Nose, Ball or Round Shape, Egg Shape, Round Nose Tree, Pointed Nose Tree, Flame Shape, Included Angle, Pointed Cone, and Inverted Taper.
- Burs come in Fine, Standard, Course, Double Cut and Aluminum cut.
- Double cut burs have teeth that result in rapid stock removal in hard materials. They produce granular type chips, and reduce bounce, chatter and offer excellent operator control.
- Selection of cut would be based on the material, and finish required.
- Standard cuts produce smooth finishes on steels, cast irons, and other ferrous metals.
- Fine cuts will produce better finish because of the additions flutes and lighter chip loads on harder materials.
- Coarse and aluminum cuts are recommended for soft materials that tend to load and pack in the flutes. These have larger flutes for faster stock removal.
use of Burrs
- Speed varies with the type of die grinder being used, size of the bur, and the material being removed.
- Start at lower speeds and increase to the speed that gives the most favorable results.
- When placing the bur into the air motor it should be inserted into the collet as far as possible to minimize overhang.
- The bur should be feathered into the cut with even pressure to avoid digging into the material.
- Do not apply excessive pressure, it can slow the spindle and chip cutting edges, let the bur do the cutting.
- Never encapsulate the bur in the cut.
- When using in aluminum, and magnesium, consider some form of lubricant, wax, or tallow, as it will help prevent the flutes from loading or packing.
- Carbide burs, if used properly will out perform HSS burs by 50:1
When selecting a vendor for burs, users should look for suppliers with modern up to date CNC equipment. In the past burs were hand ground and very inconsistent in quality, and performance. Today burs from top tier manufactures are made on CNC machines designed specifically for grinding burs. They are very high quality and consistent from lot to lot.