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Slot Drills

Slot drills are a versatile and powerful type of end mill, able to create a wide range of cuts with ease. Their performance on wood and aluminium makes them a highly valued bit, used extensively throughout key metalworking and woodworking applications.
Cromwell stocks a wide range of quality slot drills, from trusted brands used by professionals around the globe.

What are slot drills?

Slot drills (often referred to as slot drill cutters, slot mills, or 2 flute end mills) are cutting tools that are typically two fluted, flat ended, and double cutting. They have two opposing cutting edges boasting reinforced end teeth for enhanced durability and less material chipping.

Unlike other types of end mill, the cutting edges on slot drills extend to clear the centre of the bit. This means they can also perform plunge cuts.

Why a slot drill?

Similar to end drills or end mills, slot drills provide accurate cuts on the faces and edges of materials. However, they can also be utilised on the central part of the workpiece, creating blind holes - in a similar way to a standard drill bit.

With only 2 flutes, slot drills provide the best performance when it comes to chip evacuation, as the bit remains cooler for longer in operation. This, however, results in a rougher surface cut than other end mills.

Slot drills can utilise their end teeth on the sides of the drill (unlike drill bits and other cutters) providing unparalleled accuracy and versatility throughout a more diverse range of cuts, including plunge cuts - something other end mills cannot do.

When are slot drills used?

Slot drills are vital across a wide range of industries, thanks to their ability to cut in all directions. These industries include:

• Metalworking

• Woodworking

• Engineering

• Construction

• Carpentry

• Other general machining applications

If you're looking for the ideal type of slot drill (or any other end mill) for your job but aren't sure about the best one for your needs, feel free to ask our experts for specialised advice.

Considerations when choosing a slot drill

• Material - When browsing slot drills, you'll be faced with a few different material choices. The most common are HSS (high speed steel), carbide and cobalt.

HSS is the cheapest and most commonly available of the three, however HSS slot drills cut the slowest.

Cobalt slot drills are slightly pricier however they boast greater durability and can cut faster.

Carbide slot drills are the heavy-duty option, offering excellent speed, durability, and heat resistance. They can be used effectively on hard materials, such as cast iron and certain alloys.

• Coatings - Nowadays, many slot drills come with certain coatings improve the durability of the drill. Whilst not always necessary, coatings such as titanium diboride and aluminium nitride may help reduce the wear and friction inflicted upon your slot drill.
• Cut length - An obvious consideration, however it's important to ensure the cut length on your slot drill is long enough to achieve the desired result.


What materials to use slot drill on?
Slot drills, or '2 flute' drills as they're traditionally known, are best used on aluminium or any type of wood.

Can slot drills be used on stainless steel?
Some heavy-duty slot drills can be used on stainless steel. Always check the slot drill product description or manufacturers website before buying for an accurate list of uses.