Unibor annular cutters are designed to give you the POWER to cut metal with tools that last. With High Speed Steel, TCT and Cobalt ranges, alongside a variety of sizes – we have the mag drill bits to cut the hole for your next job.


24000 Series Cutters

M42 Cobalt

25000 Series Cutters


27000 Series Cutters


35000 Series Cutters


37000 Series Cutters

High Speed Steel cutters for general applications
M42 Cobalt increases cutter capability and life
Carbide Tipped Cutters cut the hardest metals at the highest speeds
M42 rail cutter geometry, designed for drilling most rail applications
Hardened carbide teeth designed for the toughest rail applications
Mild Steel
Structural Steel
Construction Steel
High Strength Steel
Fine Grain Steel
Stainless Steel
Cast Iron
Standard Railtrack
Hardened Railtrack

The Ultimate Guide To Annular Cutters, From Unibor


What is an Annular Cutter?


Annular cutters are a cutting tool designed to cut the periphery, or annulus, of a target hole. Whereas traditional twist drills cut the entirety of the hole, annular cutters cut the outline of the hole and remove the core, or ‘slug’. This has lead to the use of ‘core cutters’ when referring to these tools.

Annular cutters are therefore far more efficient than traditional twist drills. By generating less friction and removing less material, these cutters place less wear on the drill motor and generate less heat, which helps to elongate tool life.

Designed for use in magnetic drill presses, annular cutters are the ideal partner to magnetic drills due to their powerful, robust performance and hard-wearing construction. Take a look at our stock of Unibor magnetic drills for more.

Annular cutters can be found in a range of different materials, here at Unibor we offer M2 HSS, M42 Cobalt, Carbide-Tipped and both M42 & TCT rail cutters. Each option is designed to cut different materials, from general metalworking and steel to the hardest alloys and rail track.

What Does This Guide Cover?

In this guide, we’re going to cover the following:

  • What Is an Annular Cutter: Parts, How They Work & Different Types of Annular Cutter.
  • Advantages of Using an Annular Cutter: Precision Cutting, Time-Saving, Cost-Effective & Clean Cutting.
  • How To Choose The Right Annular Cutter: Material Type and Thickness,  Cutter Diameter, Cutting Depth & Shank Size.
  • How To Use an Annular Cutter: Safety Precautions, Preparation, & Proper Annular Cutter Maintenance.
  • Applications of Annular Cutters: Metalworking, Fabrication. Construction & Other Industries
  • Conclusion: Summary & The Importance of Choosing The Right Tool.

Why Are Annular Cutters Important?

Using an annular cutter is key for any metal cutting project; they offer faster, more efficient drilling than other options at a budget-friendly price. With a range of different types on the market, there’s an annular cutter for essentially any surface.

Producing fast, clean holes in metal is essential for any fabricator, construction business or other industry, there’s not a better option for drilling quick, large holes in tough metal than an annular cutter.


What is An Annular Cutter?

Parts of an Annular Cutter

We can break an annular cutter down into 5 main components, they are;


  1. Cutter Body: The main part of the annular cutter, the cutter body is typically made from HSS (High Speed Steel), designed to be strong and resistant to wear. The body design is intended to ensure that cutting teeth remain in contact with the target surface at all times, even when rotating at high speeds.
  2. Cutting Teeth: Cutting teeth are the sharp edges which create the actual cut into the material, many annular cutters use carbide tipped teeth for extra cutting power and wear resistance; our TCT cutters use Tungsten Carbide Tips for the highest levels of cutting strength. These tough materials are capable of resisting the large amount of friction and heat generated when cutting through metal, and are arranged In a circular pattern around the cutter body to remove the target material during rotation.
  3. Pilot Pin: These small, pointed rods are designed to guide the annular cutter as it cuts through the metal stock; this keeps the cutter aligned and prevents it from wandering off course during the cutting process. As well as this, the pilot pin slightly reduces the amount of torque required to cut through the metal.
  4. Flutes: An essential part of the annular cutter, flutes are the grooves which run along the length of the cutters exterior. These flutes serve a dual purpose, firstly they help to evacuate chips and debris during the cutting process, preventing them from clogging the cutter and reducing its cutting effectiveness. Secondly, they reduce the amount of heat generated during cutting, prolonging the lifespan of the cutter.
  5. Shank: The shank is the part of an annular cutter which attaches into the drill, it is designed to be strong and durable, ensuring that the cutter is securely attached to the drill during the cutting process to reduce risk of accidents and injuries. Shanks come in different sizes and types depending on the manufacturer and size of the cutter.

How an Annular Cutter Works

Annular cutters work by cutting the periphery of the hole, or the outline, usually with a magnetic drill press. This means that they cut through the minimum amount of material, making them far more efficient than twist drills and similar options. After cutting the outline of the hole, the ‘slug’ is ejected and the hole is created.

Types of Annular Cutters

You can find annular cutters in a range of different sizes, materials and designs intended to cut different materials. Here’s a quick overview of the different cutters we offer at Unibor;


Manufactured from HSS, these cost-effective annular cutters are designed for a wide range of materials. They offer excellent value due to their impressive longevity and are a fantastic option for general metal fabrication.


Using steel with a higher percentage of cobalt, these cutters are designed to cut through tougher materials and last longer than the M2 options.

Carbide Tipped

Designed with ultra-hard Tungsten Carbide Tipped teeth (TCT), these cutters are intended for the hardest materials, including; cast iron, high tensile steels and thick metal surfaces. Their specialist teeth also provide enhanced longevity, even on these tough metals, making them ideal for use with magnetic drills and other drill presses.

Rail Cutters

Featuring specialist geometry designed for use on tough rail track, our range of rail cutters are ideal for railway maintenance and similar applications. With M42 and TCT options available, there’s a cutter ready for the best possible finish on tough rail materials.


Advantages of Using Annular Cutters


Precision Cutting

Annular cutters are fantastic for cutting holes in tough metal with a high degree of accuracy. Metalworking and fabrication necessitate accurate, precise holes to ensure proper performance of the workpiece. Annular cutters are therefore ideal for drilling holes in components in construction, machinery and vehicles, amongst other options. With a magnetic drill press and correct annular cutter, it is easy to make quick, accurate holes in tough metals without issue.


This ability to make quick cuts is a fantastic asset within industries like steel fabrication, where drilling fast, repeated holes to product products is a vital asset in this field.


Annular cutters are robust tools, when used properly they can last for a long period of time and can be re-sharpened for reuse. This makes them highly cost-effective tools, capable of providing a fantastic return on investment. Our M2 HSS (High Speed Steel) range of annular cutters is a perfect example of tough, hard-wearing tools built to last.

Clean Cuts

Annular cutters produce cleaner holes with less burr than other options due to their intelligent design and cutting ability.


How to Choose the Right Annular Cutters


Material Type and Thickness

The first thing to consider when choosing an annular cutter is the materials being drilled; how hard are they? How deep do you need to drill? What diameter hole do you need to make in the workpiece? Failing to account for any of these factors risks jeopardizing the workpiece, cutter and operator safety.

Cutter Diameter

Beginning with cutter diameter, this is relatively self-explanatory: how wide is the hole you need to cut? Consider the cutter diameter of the magnetic drill you’re using as well, this will also have an impact.

Cutter Depth

Depth of cut is also an essential aspect of this decision-making process, ensure that the measured depth is sufficient for drilling through the thickness of the metal.

Shank size

Annular cutters come with different shank sizes. consider your magnetic drill’s capacity before choosing a cutter.


How to Use an Annular Cutter


Safety precautions

Staying safe with an annular cutter is relatively simple; ensure that the cutter is well maintained, not overly worn and used properly. Ensure that proper eye protection is worn to avoid potential metal chips and debris from injuring the operator.


Ensure that the cutter is properly lubricated and the workspace is clear. Using appropriate coolant will elongate the lifespan of the cutter by reducing friction and heat generation during the cutting process.

Maintenance and care

Proper maintenance and storage of annular cutters will ensure that their working lifespan is as long as possible, reducing the risk of excessive wear and damage.


Applications of Annular Cutters



Annular cutters are used in a wide range of different metalworking industries, their ability to make quick, clean cuts in a range of metals is ideal for producing quality metalworking finishes and projects.

Steel Fabrication

Steel fabrication is a particularly big industry for annular cutter use, with businesses across the world using these tools for their ability to cut through tough metals quickly and accurately. In an industry where efficiency and a quality finish are valued, these tools are vital.


Construction needs powerful, cost-effective tools which can cut through materials like tough structural steel quickly. Annular cutters allow these clean, rapid cuts to be made on a variety of different workpieces.

Railway Maintenance

Railway track is extremely tough metal, built to withstand immense pressure during use. That’s why specialist annular cutters, designed to cut through the toughest tracks in the country and beyond, are used throughout the railway sector.

Other Industries

Any industry that values performance, value and efficiency in a metalworking project stands to benefit significantly from using annular cutters. From shipbuilding to bridge repairs, these are critical tools across the world.



In Summary

Overall, we’ve covered the essential details around annular cutters; what they are, what they do, how to use them and where they’re used. These fantastic tools are ideal for producing fast, clean cuts in tough metals, making them a vital asset to businesses around the world.



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