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CNC machining is one of the most wonderful innovations in modern manufacturing technology. This highly versatile technology can produce almost any component, with some coding and intricate tools like drill bits and end mills. However, both end mills and drill bits look almost identical, and picking the right one for the job can sometimes be quite confusing.
It is very common for a newbie in the CNC machining process to confuse a drill bit with an end mill. Since they differ vastly in their applications, you will need to understand how to tell them apart. And that is exactly what we are going to do in this article as we uncover all their differences and end the confusion once and for all.
What Is An End Mill?
End mills are among the most commonly used cutting tools when it comes to industrial manufacturing operations. They can be made of different materials, such as steel, carbide, ceramics, and even diamonds. You need to select the material of your end mill based on the task you are performing. For example, end mills with high-speed steel inserts are suitable for shaping special tools, whereas the ones with carbide inserts are appropriate for high-production milling. Usually, a milling cutter has a diameter from 1 to 25 mm. There are also micro-end mill cutters with less than 1 mm diameter. The cutting edges of the end mills are called “flutes,” and the number of flutes ranges from one to sixteen.
Primarily, there are four types of end mills: flat-end, corner radius, ball nose, and flat-end with chamfering. Flat-end end mills are undoubtedly the most popular choice for fine milling action. The other types are used based on what the job requires – rough milling or finishing. An end mill is designed to cut both radially and axially. That means, while cutting, it can go both downwards and sideways. This amazing adaptability of end mills makes them the most adored sculpting tools in the world of industrial component production.
When To Use End Mills?
End mills should be your first choice if you want to make large holes. As they go sideways, you can move the mills to make the holes bigger gradually. If you do the same job with a drill bit, you will need a bulky one with a lot of power, both of which are costly. For any rotational cut, whether it is a hole or not, end mills are often the first choice of experienced machinists. As end mills offer flexibility with movements, they can be used to precisely create any shape or indent you desire.
If the job in hand requires holes of different sizes, you might want to stick to an end mill. It saves you from the trouble of changing the drill bits again and again as the hole diameter changes. Moreover, there is no alternative to end mills to make a clean, flat-surfaced hole.
What Is A Drill Bit?
Drill bits are cutting tools that are specifically designed to drill holes. Depending on the surface, you need to pick the appropriate type and size. Drill bits are also faster and stronger than end mills. Based on the size, a drill bit can make holes of 2 to 40mm in diameter. There are five common types of drill bits: center drill, twist drill, deep hole drill, flat drill, and sleeve drill. The most popular one is the twist drill, with two cutting edges.
Drill bits are designed to cut only in an axial direction. That means they can bore holes only straight down. Therefore, you cannot move around as you can with end mills. When choosing a drill bit, you must take the hole’s shape, diameter, and material into account. Based on the function, drill bits are made from various materials, including carbide, carbon steel, high-speed steel (HSS), and so on. HSS bits are capable of drilling for a long time, whereas high carbon bits are better for softer materials like wood.
When To Use Drill Bits?
For drilling deep holes where the depth is more than four times the diameter, drill bits are your best bet. End mills are not suitable for creating deep holes because they are weaker in construction than drill bits. Drill bits are usually recommended for drilling holes with less than 1.5mm diameter. This is because drill bits can work more vigorously than end mills. Therefore, drill bits are better for making smaller holes.
If the job requires drilling tons of holes of the same dimensions, then you should use a drill bit. These bits will help you do the job much faster and more precisely. Also, it is often recommended to use drill bits on tougher materials.
End Mill vs Drill Bit: The Differences
Now that you have a basic understanding of what end mills and drill bits are and their applications, it’s time to see how they differ.
|End Mills||Drill Bits|
|Designed to make cuts, cavities, and indents of various shapes||Designed only to create round holes on surfaces|
|Can cut with both vertical and horizontal motions||Can cut only downwards|
|End mills are available in a range of sizes and shapes. The most common mills come with a flat tip or ball nose||Except for the diamond ones, drill bits usually have a cone-shaped head|
|Shorter in length||Comparatively longer in length|
|Cutting edges are located at the periphery, as well as on the bottom||Cutting edges are located on the bottom only|
|Form small continuous chip||Form long continuous chip|
|The usual aspect ratio of cut is 10:1 (the depth is ten times the diameter)||The usual aspect ratio of cut is 2:1|
|Feed motion is two-directional. The bit can be moved toward the workpiece, or the workpiece can be moved toward the drill||Feed motion is one-directional; usually, the tool stays in place, and the workpiece moves|
|Can cut a flat-bottom hole||Cannot cut a flat-bottom hole; always produces a cylindrical surface|
|End mills are available with one to sixteen cutting edges||Drill bits are available with two to four cutting edges|
|Can be used with high rotational speed as no issue with chip evacuation is likely to arise||Used with low rotational speed to avoid issues with chip evacuation|
|Uncut chip fragments do not have uniform thickness everywhere||Uncut chip fragments have uniform thickness everywhere|
Which One Should You Pick?
As you can see, both end mills and drill bits are equally useful for a range of applications. Each of them has its own unique perks to offer. Although investing in both tools is a wise choice, picking which one to pick comes down to the type of project and tasks you have. If your task requires different-sized holes or multi-directional movements, pick end mills. If you need to make tons of same-sized deep holes on a tough surface, go for drill bits.