by Natalie Edwards

Rotary burrs? Tungsten carbide? Single or diamond? Shape? There's a lot to consider when choosing the right rotary burr for the job at hand. Our guide below will teach you everything you need to know about choosing the right rotary burr for your metal fabrication...

 

What are rotary burrs for?

A rotary burr is a rotating tool that is used for removing material. They are designed to rotate at a very high speed which enables it to manipulate the material it is working on. When working with metal, burrs are great for deburring, shaping and enlarging holes. Tungsten carbide rotary burrs can be used on all metals including steel, stainless steel and aluminium. They are commonly used by metal fabricators and engineers for tool making, model engineering, jewelry making, welding, deburring, grinding, and sculpting.

Tungsten carbide vs HSS

Generally a metal burr is made from either Tungsten Carbide or High Strength Steel (HSS). Tungsten carbide burrs are preferred when working with metal. Due to their extreme hardness they can be used on much more demanding jobs and won't wear out, unlike HSS. What's more, HSS has less tolerance for heat and will start to soften under high temperatures. Tungsten carbide burrs will last longer and perform better under higher temperatures.

Why we recommend Tungsten carbide burrs?

  • High stock removal
  • Great for deburring, shaping, smoothing welds, enlarging holes, carving and finishing
  • Last longer
  • Perform at high temperatures
  • Ideal for all metals

Where tungsten carbide burrs can be used on any metal, there are different cuts available to suit different metals, see below.

Types of cut

Metal burrs come in either a single/aluminium cut, or a double/diamond cut. Large single/aluminium cut carbide metal burrs have a single right cut spiral flute and are used with cast iron, steel, copper, brass, and other ferrous materials such as aluminium. Single cut burrs will provide faster stock removal with no clogging (clogging is common with aluminium), however they will not provide as smooth finish as double cut carbide burrs. Double/diamond cut have both a right and left hand cut providing a faster and finer finish. These are commonly used on steel, stainless steel and other hard metals.

Aluminium cut

  • For use on Aluminium and softer materials
  • Faster stock removal with no clogging 

Double cut

  • Most commonly used on Stainless Steel and Steel
  • Right and left hand cut giving you fast and finer finish

Shapes

Cylindrical end cut SB

• Surface milling, right angle corners

Cylindrical ball nose SC 

• Machining contours and circular arcs 

Ball shape SD

• Rounded end milling, preparing for welding

Oval shape SE

• Rounded contouring and end milling 

Tree shape round nose SF

• Multi-angle contouring, rounded and narrow

Cone shape round nose SL

• Enlarging holes, rounded edges and narrow place 

Flame shape SH

• Round edge, milling, preparing for welding

Tree shape pointed nose SG

• Multi angle contouring, pointed and narrow places

Size

Tungsten carbide burrs come in a variety of sizes to suit different applications. Choosing the right size will depend on the job at hand. Generally smaller burrs are used on smaller applications for producing finer, smoother work. Larger burrs are for higher, faster stock removal and are more often used on larger jobs.

Size No.  Burr size  RPM 
No.42  2.4mm 17,000-26,000
No.43 3.0mm 17,000-26,000
No.1 6.0mm 11,000-16,500
No.5 13.0mm 8,000-12,000
No.6 16mm 7,650-11,500

Speed

The rotary tool speed you use will depend on the metal and size/type of burr used. For optimum performance and results it is always best to check the manufacturer recommendations for the correct RPM to use with each metal burr. Ideally you will start off at a lower speed and increase as you go along, however if you find your burr is chipping it is a sign you are going too slow.

Technique

For the best results, and to make your burr last longer, make sure you don't use too much pressure while cutting. Too much pressure will cause the cutting edges of the flutes to chip and become smooth prematurely, reducing the life of your burr.

You will also want to ensure you keep the burr moving around the cutting area as much as possible. If the metal burr is left still for too long this can cause clogging and stop it from digging and jabbing into the job, leaving a rough job with visible marks.