What Kind of Drill Is Best for Metal?

Being able to effectively drill holes in metal can speed up jobs, open up new possibilities for projects, and enable various fabrication techniques to be used. However, problems can arise when the incorrect tool or technique is used.

This guide explains all there is to know about drilling holes in metal, including what bits to use, why some bits work better than others, and a step-by-step guide on how to avoid breaking drill bits.

What is Drilling?

Drilling is a rotary cutting technique whereby a round hole is created through a piece of material or object. Holes can be drilled in almost any material, with the right tools, but different materials often need vastly different tools and techniques.

Drilling can be done with anything from a hand-operated drill to building-sized drilling rigs used to drill into the ground. In this guide, we’ll mainly be focusing on electric-powered drills, such as drill presses, or battery-powered tools.

What Makes Drilling Metal Different from Wood or Masonry?

Metal is incredibly useful, in part thanks to its hardness and strength; unfortunately, these properties make it harder to work than other materials, such as wood.

Hardness is the property of a material to withstand abrasion, penetration, or deformation. The hardness of metal is many times higher than that of wood. This means a drill for metal needs to be far harder to avoid being worn away during drilling.

Because of the high hardness, a key consideration when drilling metal is managing the heat produced. This can be a problem when drilling wood too, but the lesser forces make it less of a problem.

When drilling metal, the bit needs to be kept as cool as possible. Allowing the end of the bit to heat up excessively, such as when the drill is not very sharp, will heat the cutting edges to the point they lose their hardness.

Drilling Masonry

Drilling masonry is different from both wood and metal, as the material often has a high hardness but very low toughness (the ability to absorb energy when impacted), meaning it is quite a brittle material.

For this reason, masonry drills need to be very hard-wearing, with many having carbide tips to resist abrasion. But they still need to be tough, as the best way to drill masonry is with a hammer drill.

Hammer drills force the drill bit into the material multiple times per second, as if hitting the back of the drill with a hammer. This causes the masonry to crack and break off, allowing the hardened tips to scrape the loose pieces away.

Best Drill Types for Metal: Corded, Cordless, and Drill Presses

Drill Press

To drill metal effectively, the drill should be pushed into the material with a significant amount of force. This allows the cutting edges to bite in, rather than rub on the surface and generate heat. For this reason, a drill press will always make drilling easier than a handheld drill.

Magnetic base drill

However, it is not always possible to make the required hole with a drill press if the part is too big or the drilling needs to be done “in position” on a beam or other object.

In this case, the next best option is a magnetic base drill. Also known as mag drills, these portable devices use a powerful electromagnet to stick to the workpiece. They generally run on mains electricity, but battery-powered ones are available.

A rack and pinion, chuck, and motor similar to a drill press allow sufficient force on the drill bit, making drilling easy and safe.

Corded or Cordless hand drills

While there are multiple shapes and configurations of mag drills, sometimes a hole needs to be made with a handheld drill. This is the least preferred option, as it requires much more effort and skill from the user to avoid injury, broken drill bits, or inaccurate holes.

In general, corded drills are more powerful than cordless, but some manufacturers are making high-voltage battery systems that may be close to overtaking the old main-powered tools.

Best Drill Bits for Metal: HSS, Cobalt, and Carbide

Many different materials are used to make drill bits, each with differing strengths and weaknesses.

HSS – High Speed Steel Drill Bits

HSS drill bits are the cheapest type of drill bits; typically, they come uncoated and can be used for a wide range of metals sparingly. With proper care, correct cutting geometry, feed rates, and speeds, they can last a long time when used on mild steel and other similar materials.

However, if you need to drill stainless steel regularly, or any other material harder than mild steel, such as cast iron or titanium, HSS bits are likely to dull quickly.

Cobalt Drill Bits

While still mainly composed of high carbon steel, cobalt drill bits contain 5-8% cobalt, which increases the hardness dramatically, allowing them to hold an edge for longer, even when cutting harder materials.

Another benefit of using cobalt drill bits is the ability to drill faster: their higher heat resistance allows more aggressive feeds, improving productivity.

Cobalt drills are more expensive than HSS, but not prohibitively so, typically costing between 1.5 and 3x more.

Carbide Drill Bits

Tungsten Carbide is one of the hardest materials in the world and as such makes for an incredible drilling and machining tool material. Solid carbide drills can be used in normal battery and pillar drills.

Carbide drills are often used in high-speed production environments that require the very best tool life and speed, even in very hard materials.

The downside is cost; solid carbide drills can easily be 10 times more expensive than HSS.

Compared Drill Speed, Torque, and RPM Settings for Metal Drilling

Another crucial factor in drilling effectively is what is known as “speeds and feeds.” This common industry term refers to the RPM the drill is spinning at and the feed rate at which it’s pushed into the material.

While it is most relevant to machining, where these parameters are tightly controlled, it does have relevance to hand drilling too, as getting the correct rates can be the difference between successfully drilling many holes and blunting a drill bit in minutes.

Below is a table of ideal RPMs when drilling various metals. This can be used as a guide, but considering most battery-powered drills max out at around 1,900 RPM, the ideal conditions are hard to meet unless a drill press or mill is used.

Tips to Drill Metal Cleanly Without Breaking Bits

Using the wrong technique can ruin a high-quality drill bit in a matter of minutes. While the material and the type of hole have a large impact on the performance of the drill, there are some tips you can follow:

• Use coolant or purpose-made cutting oil on any drilling operation
• If drilling a deep hole, retract the drill fully from time to time to clear chips that could become lodged and jam the drill
• Keep a firm, even pressure on the drill
• Centre punch the hole before drilling, to improve accuracy
• Don’t allow the drill to “rub” on the surface; either push firmly to make progress, or remove the drill from the work
• Select the right type of drill for the work and ensure it is sharp

Find the Metal You Need from Metal Supermarkets

Whether you’re making a project in your garage or need bulk materials for industrial fabricating or machining, Metal Supermarkets can help. Choose from a large range of metal types, grades, and shapes, and have them cut to size, too! Browse the range here.