Carbide burrs are small rotary tool bits used for cutting, shaping and grinding. They prove handy when removing excess material, smoothing rough surfaces and edges, and for general deburring purposes. Their versatility and unrivalled strength mean they can be used across various materials, from iron, aluminium, titanium, and precious metals like gold and silver, hard and softwood, to ceramics, tiles, and hard plastics. The bits are usually found at the business end of industrial-grade milling machines and die grinders, but also dentistry drills, and rotary tools used by jewellers and sculptors.
Burr Basics
The small differences and the tools they’re used with lend burr cutters different names. They go by die grinder bits, die grinder burrs, and rotary files among other names. Their main use is to cut and finish materials while spinning at very high speeds. The tool attachments are ideal when removing surface imperfections (burrs) and excess materials, grinding and milling, creating holes, clearing weld spatter, chamfering… the list goes on.
The bits are made of the hardest alloy – tungsten carbide (hence carbide burrs), and come a close second only to natural diamonds for overall hardness. This makes them extremely durable, able to cut into any material without blunting, overheating, or deforming. The bits run circles around other tool attachments, notably regular High-Speed-Steel (HSS) and are exceptionally efficient in harder materials.
What They’re Used On
Die grinder bits can be used on metals, wood, plastics, ceramics, and tiles. Common materials include:
- Ferrous metals and alloys – cast and wrought iron, carbon, mild, tool and stainless steel
- Non-ferrous metals – aluminium, copper, lead, tin, zinc
- Precious metals – gold, silver, platinum, and copper alloys such as bronze and brass
- Hardwoods – oak, maple, walnut
- Softwoods – pine, cedar, fir
- Plastics and fibreglass
- Ceramics – tiles, brick, porcelain, glass
- Bone, ivory, teeth
Diamond-coated burr cutters are also used for shaping, smoothing and engraving semi-precious and precious gemstones.
Common Applications and Industries
The huge range of materials makes carbide burrs a precise and effective cutting tool in numerous industries. This includes carpentry, woodworking and joinery, tool machining, engineering, construction, plumbing, automotive repairs, welding, dentistry, jewellery making, sculpting, artwork and dozens of other specialist applications.
Choosing the Right Cutting Profile
There are two main types of cutting profiles to choose from. These determine where and how the bits are used. Single-cut profiles have a right, spiralling cutting profile from the tip to the bottom. The design is more effective in stock material removal, such as thinning uneven workpieces, and works better at faster speeds. Bits with single-cut designs are also ideal in coarser metals where they work exceptionally well in general deburring and milling. Go with single-cut burr cutters when smoothing out rough surfaces, tending to edges, or removing weld spatter.
Choose double-cut profiles for smoother finishes. These have finer left and right intersecting cutting flutes. The design is ideal for surface finishing, polishing, carving and engraving. They can also be used in light milling tasks. Double-cut designs are more forgiving as they cut or remove less material in a single rotation, and therefore more precise. And they’re equally capable in both hard and soft materials.
Why Size and Shape Matters
Shapes determine the type of cut you’re looking to get. They can also help when working in tight spaces. Ball burrs are used for concave cuts when hollowing out wood and metals. Choose tree burrs with rounded or pointed tips to get acute angles, and when smoothing edges, or inverted cone burrs when making v-cuts and for chamfering purposes. Pointed cone variants are good for surface finishing, rounding edges and working with tighter angles in hard-to-reach spaces.
Other shapes include oval and flame burrs for rounded edges and countersink types at 60 or 90-degree angles when bevelling, counter-boring, countersinking and chamfering. The pointed tips also work wonders in harder materials.
Also, consider sizing burrs for the intended application. This is stated in metrical or imperial units and refers to the diameter of the burr head. Sizes range from 1.6mm (1/16″) to 16mm (5/8″) for most uses and impact the size of the cut or hole, but also operating speeds. Smaller burrs can spin faster (with dental drills reaching 400,000 RPMs), while those intended for wood and metal and in moderate diameters of 3 to 6mm can reach speeds of 20000 RPMs. Bigger types are more effective at tool speeds averaging 10000 revolutions.
Speeds can additionally be altered to meet cutting needs. Harder materials like steel will need faster RPMs, usually 35000 for smaller burrs, or 10 to 15 thousand when working with bigger units. For softer materials like wood, you can use lower RPMs to achieve smoother cuts and higher precision.
Head diameters generally correlate with those of the shanks, and the tool chucks that the bits attach to. Also, pay attention to shank lengths. Besides standard sizes, there are extra-long shanks, helpful when working in constricted areas. Lastly, ensure you get burrs compatible with the rotary tool you’re using in your line of work. If this includes various tasks, shop for packaged sets with sizes and shapes that meet your needs.
