Metals, Drilling and Picking the Best Drill Bit
In this article we explain what features to look for to find the best drill bits for drilling through metal. There are a number of different types of metal ranging from light weight metals such as aluminum, and also softer metals such as lead and all the way up to the hardened steels and cast irons.
Depending on the type of metal that you want to drill, there are also different types of drill bit available. We have produced a long and extensive drill bit for metal buying guide just below. Please feel free to read through it all if you want to find out everything about drill bits designed for drilling through various types of metal.
If you prefer, you can click on the table of contents below, and pick out a preferred section of reading.
Different Types of Metal
There are many different types of metal that include;
- Aluminum - lightweight metal
- Brass - an alloy of copper and zinc
- Bronze - an alloy of copper and tin
- Cobalt = a silver gray metal usually used for making Lithium-Ion batteries and some jewelry and paint
- Copper - This is a soft metal and is mainly used for electrical wire, roofing, plumbing and some industrial machinery
- Iron - includes wrought and cast iron and used for gates, fencing and some cookery utensils
- Lead - this is a heavy but malleable metal. It is used mainly in battery production.
- Magnesium - a shiny gray metal mainly used in aluminum alloys, die casting and some steel alloys
- Nickel - This is a silvery white metal and mainly used for producing stainless steel, in many alloys and for electric guitar strings, microphone capsules, and the plating on plumbing fixtures
- Steel - includes carbon steel, alloy steel, stainless steel and hardened steel - these are all very popular and widely used
- Tin - This is a silver metal and is used for solder, tin plating, making alloys, making LCDs ad some jewelry
- Titanium - This is a silver color with low density and very high strength. It is resistant to sea water and is used in paint, paper, toothpaste and plastic. It is also widely used in aerospace and marine for a wide range of products
- Tunsgten - This is quite a rare metal and is used for a wide variety of alloys for a wide variety of cutting tools. It is also used in the electronic, aerospace and automotive industries.
- Zinc - It as a blue/silver appearance and is quite brittle for a metal. It is almost exclusively used as an anti-corrosion agent or for galvanizing
Most of the metals are classed as hard materials, and as such they require special drill bits to be able to get through them easily. Many of the metals listed above are primarily used as alloys. That simply means that they combine with other metals to make a stronger, durable and more flexible type of metal.
There are plenty of choices of metal available, and it depends on what job that metal is used for, as to what type of metal a manufacturer will pick.
In this article we will take you through what we believe to be the best drill bits, and drill bit sets for getting through the different types of metals.
It is worth noting though, that most drilling of metal will be through the various types of steel.
Who Buys Drill Bits for Metal?
The average person will have very little reason to ever have to drill through metal. Unless you have a particular hobby, or do some type of home renovation, there will not really be that big of a requirement to ever have to drill through any type of metal.
At some stage we may need to drill through wood or plastic. Nevertheless, there may be the occasional time when we need to make a few holes through different types of metal.
Many professionals such as engineers, construction workers, electricians etc have a regular need to drill through the many different types of metal.
What Are Drill Bits for Metal Made Of?
Most metals are classed as hard materials. Any drill bit that you use therefore needs to be harder than the metal you are drilling through. Most drill bit manufacturers make their drill bits by hardening steel with another metal such as titanium or cobalt.
They also make sure that this is concentrated at the very tip of the drill bit, as that is the focus point of the drill bit. That point of the drill bit is referred to as a "pilot point," and the drill bit point is usually coated in a very hard metal, again using cobalt or titanium.
Drill Bit Material Comparison Table
Just below you will see a drill bit comparison table. HSS drill bits are the most affordable and if you buy a drill bit with cobalt or titanium coatings, they will drill through metal faster, and last longer. As you would imagine they are also more expensive.
Drill Bit Material
High Speed Steel (HSS) drill bits
These are the most common and they are suitable for drilling wood, fiberglass, PVC and soft metals like aluminum.
Cobalt drill bits
These are very hard drill bits and also very good at dissipating heat very quickly. They are a very good choice for drilling aluminum and tougher metals such as stainless steel and cast iron
Black Oxide Coated HSS drill bits
The black oxide coating helps the drill bit resist corrosion and rust, and as such helps extend their life. They will last longer than your standard HSS drill bit and can be used to drill metal, wood, PVC and fiberglass. (mainly used for wood)
Titanium Coated HSS drill bits
When you add a titanium coating that helps reduce the amount of heat and friction on the drill bit. That makes them much tougher than a standard HSS drill bit and also helps them stay sharper for longer. These are suitable for drilling metal, wood, PVC and fiberglass.
Carbide Tipped drill bits
These are the highest quality drill bits and they will stay sharper for much longer than steel, HSS or titanium bits. These are primarily used for drilling tile and masonry.
Main Parts of a Drill Bit
Drill Bit Diameter - this is the diameter of the size of the circular hole that a drill bit can make. Typically users buy a drill bit set that includes sizes from 1/16 inch to 1/4 inch which will work for many jobs around the home and workshop. You can add larger bits — 5/16-inch, 3/8-inch, 7/16-inch and 1/2-inch bits — if you need them.
Drill Point Angle - If you look at the point of any drill bit, you will notice that it has an angle.
- Drill bits for wood usually have an angle of around 118 degrees.
- Metal drill bits have an angle of 135 degrees which is more suitable for metal and harder materials
Drill Point Flutes- These are shaped grooves that are formed in the body of the drill to provide cutting lips. These lips then allow the removal of chips, and also allow cutting fluid, when required, to reach the cutting lips.
Drill Point Shanks- This is the part of the drill bit, that is gripped by the chuck of the drill or drill press. Most drills for home use use a 3/8" chuck size, but for heavier duty drilling and for most drill presses, the preferred chuck size will be 1/2" or 5/8".
It is very important when buying any drill bit, that the thickness of the shank is not bigger than the chuck on your drill. Some manufacturers do make drill bits with a "reduced shank" which is smaller than the diameter of the drill bit.
There are three types of drill bit shank:
- Round shanks - this is the most popular and allows you to easily center a drill bit into a drill chuck. Under heavy drilling they can start to slip
- Hex shanks - These have flat surfaces, that allow the chuck to grip the bit more securely for greater torque. They are now very popular for using with a cordless drill as they allow you to insert and remove them without having to tighten and loosen the chuck.
- SDS shanks - This is known as a "slotted drive system" (SDS) and is designed for using with a hammer drill. It fits a spring-loaded chuck that doesn't require tightening. The bit can move forward and backward with the hammering motion of the drill, while flattened areas and slots on the shank allow the chuck to hold the bit.
Hopefully the information explained above has helped you understand what the parts of a drill bit are, and also what to look for when drilling through the various types of metal.
Single Drill Bit vs Drill Bit Set
There are some very good general purpose drill bit sets, that are ideal for drilling a variety of different sized holes in most metals. The beauty of these types of sets, is that you have a good wide range of different sized bits.
You will always get the most commonly used sizes, and also some at the lower size, and some at the higher size values. The beauty of the sets is that you will almost always get much better value for money, than if you were buying them as individual bits.
The downside is that you usually end up with some bits that you will never, or hardly ever use. It is question of deciding if these are the better value choice for you.
For most people though a drill bet set for metal is a very good idea. You can however also buy a single size drill bit if you only have a small amount of drilling to do, or just one particular size of hole to drill.
Type of Drill Bits for Metal
There are really only 2 choices when it comes to buying drill bits suitable for drilling metal.
Twist Drill Bit
A twist bit is the most common type of drill bit for home use. It works for general-purpose drilling in wood, plastic and light metal. As we have explained above, these can be bought as a single drill bit, but are more commonly available as a drill bit set.
Step Drill Bit
A step bit is designed primarily for drilling in thin metal, up to 1/4 inch. The stepped design allows you to use a single bit to drill holes with different diameters. Often the diameter of each step is etched into the metal drill bit. You can also use this type of bit to deburr holes, clearing away waste material.
Best Drill Bit for Aluminum
Aluminum is used a lot in today's global market. Mainly that is because it is light in weight and yet strong. Aluminum is now a key engineering material and is used in our homes, our automobiles, trains, aeroplanes and also in smart phones and computers.
Aluminum is easy to process and it can be rolled, pulled and stamped and most importantly it is not toxic. It is also very pliable so can be made into thin sheets and even foils. It is also one of the cheapest metals to make.
Aluminum is a soft, nonferrous, ductile material with low density and has a naturally high resistance to corrosion. That may sound like drilling through aluminum is easy, however because aluminum is soft it causes the material to make constant prolonged contact with the rake face, or cutting edges, of a drill bit.
Aluminum is also used in a wide variety of alloys, and the blend of these alloys is what determines how hard the material is to drill through. In most aluminum alloys will build up and stick to the cutting edge and clog the flutes.
The best drill bit for aluminum is a drill bit with a 130° to 140° point angle and polished flutes will provide the best chip clearing and cutting performance.
Best Drill Bit Sets for Steel
You can buy drill bit sets that are designed to be able to drill through many of the steels that are available on the market. These include normal steel, hardened steel, alloy steel and stainless steel.
Steel is the metal that most people may have to drill through. Normal bits that we have shown below will be able to drill through steel very well.
Hardened steel is a different metal, and we have included a section just below just on that material. If you need to drill through that, then check out the section below.
Best Drill Bits for Stainless Steel
What is Stainless Steel?
Stainless steel is an alloy, which means it contains a number of different components. It does come in different grades. To be classed as stainless steel it does have to have 10.5% Chromium. Chromium is the thin layer of oxide which is always on the surface. It is this layer that stops corrosion of the surface. The higher the percentage of Chromium used will give an increased resistance to corrosion.
It depends on what the stainless steel is going to be used for as to what other elements are added to it. Almost always there will be carbon, silicon and manganese. In some cases other elements such as nickel and molybdenum may be added to impart other useful properties.
Stainless steel has a wide variety of uses such as cutlery, saucepans, sinks and a lot of catering equipment. It is also widely used in a range of medical equipment and in the automobile industry. Think of items such as surgical instruments and car exhausts to name just a couple.
There are 5 types of stainless steel and they are known as:
- Ferritic – This stainless steel has small amounts of carbon usually less than 0.10%. They can't be hardened by heat treatment.
- Austenitic - These stainless steels are by far the most common. They have elements of nickel, manganese and nitrogen. This allows this type to be easily formed and welded.
- Martensitic - These steels are similar to ferritic steels but have higher carbon levels That allows them to be hardened and tempered much like carbon and low-alloy steels. They are used where high strength and moderate corrosion resistance is required.
- Duplex - These steels have a microstructure which is approximately 50% ferritic and 50% austenitic. This gives them a higher strength than either ferritic or austenitic steels.
- Precipitation hardening (PH) - These steels can develop very high strength by adding elements such as Copper, Niobium and Aluminum to the steel.
Just below we have included our recommended drill bits for stainless steel.
Best Drill bit set for stainless steel
Best Budget Drill bit set for stainless steel
Best Step Drill bit for stainless steel
Best Drill Bits for Hardened Steel
Hardened steel is a particularly tough metal to get through. These require a special type of drill bit. I have done a more detailed article on the types of drill bit required to get through this very tough metal.
When steel is hardened it is heated to very high temperatures. It can however only be hardened and tempered if the steel contains high quantities of carbon.
When steel is heated it becomes quite brittle, and the tempering process then reduces the hardness slightly, to remove this brittle nature. It is one of the more tough metals to drill through.
Best Drill Bit Sets for Brass
Brass is an interesting metal, and one that I really do enjoy working with. Most of the general metal drilling bits will go through brass, however there are drill bits that are better for drilling through brass.
The set to the right seems to be a very popular choice with buyers. This is a set of titanium coated HSS step drill bits, a good choice for making different sized holes.
Drill Bit Buying Guide for Metal
There are a number of considerations to examine when it comes to drilling at the right speed through metal. The one thing you should remember that drilling too fast, will cause your drill bits to burn out very quickly.
That is one of the main reasons why it is vital to have a variable speed setting on the drill that you are using. Most drills will come with a manual and in there you should find the recommended speeds for the different materials including the metals.
With a softer metal like aluminium you can go faster, but in my opinion slower is always best to stop ruining your drill bits.
What should really guide your speed is the actual size of the hole that you are drilling. The bigger the diameter of the hole, the slower that you need to go, is always the golden rule.
At the bottom of the page I have included a Drill Bit RPM Guide for Metals
Drilling Through Metal Problems and Solutions
Below I have listed some very common problems that people discover when they drill through metal. I have provided what the problem is likely to be and how to resolve that.
Problem - the drill bit is making a high pitched squealing noise
Solution - Most likely the drill bit is running too fast. You can either slow down the speed, or if you don't have a variable speed, drill in short bursts, leaving time in between each drilling session
Problem - The drill bit becomes very hot
Solution - This can be caused by one of two things. Like the problem above the drill bit is going too fast. If that is the case, then the same solution as shown above will help solve that problem.
Secondly the drill bit may require some lubrication. You can buy spray tins of drilling and cutting oil to help resolve this problem. You can also use water to help keep the drill bit cool.
Be careful with water though especially if you are using a power drill plugged into an electricity supply.
Problem - your drill bits get blunt very quickly
Solution - the solution to this is that your drill bits are over heating and you should use lubricant as explained above. Just be aware though that if the drill bits have been over heated a lot, they are practically useless and may need replacing.
Most drill bits can be sharpened, but that takes some skill, and it is always better to buy a drill sharpener machine.
Problem - the drill bit is wobbling
Solution - The bit may not be centred in the chuck, so always check that first. That is always a big problem when using very small bits, such as when you are drilling a pilot hole. Often the drill bit gets caught in just one jaw of the chuck, and it is off center.
The other problem could be that the drill bit has been damaged, and is bent or even slightly warped. If that is the case, then it will need to be replaced.
Problem - the drill bit slips and skids across the metal surface
Solution - No matter what type of metal you are drilling, there should always be a pilot hole drilled first. Usually this is done using a very small drill such as a 3 mm drill bit.
However before that, a center punch should be used to make a dent in the metal, that will accommodate the pilot hole drill bit. Makes sure that you do that, and that it is deep enough to allow the small metal drill bit to grab the metal.
Problem - Drill Bit Jams in the Chuck at the end of the drilling
Solution - this is one of the most common problems when drilling through metal. The honest answer is that this is usually caused by our impatience. It is all too easy when getting near the end of the hole, to force it through.
Too much pressure or weight on the drill bit will cause the drill bit to jam or lock up in the chuck if we try to force it through. Go easy on the pressure and allow the drill bit to cut all the way through the metal.
As mentioned earlier in the article, I have included a speed drilling guide for metal.
Please note the drill bit size is shown in inches, and the RPM is shown as the maximum RPM the drill bit should be used when drilling.
Drill Bit Size
Hopefully I have provided you with enough information to allow you to pick the best drill buts for drilling metal. Thankfully most home owners will have very little need to do this.
For those that do I hope this article has helped you out.