The importance of drill speed
In this article
Drill speed is expressed in RPM or revolutions per minute. This is a parameter, a unit of measurement, used to express angular velocity or frequency, as well as the number of turns per minute that a drill bit can complete. Why does it matter so much when choosing a drill?
Measuring revolutions per minute
All machine tools have revolutions per minute, or RPM. They measure how many times the cutting tool can rotate on its own axis to machine a workpiece. In other words, they indicate the number of rotations per minute. Even cars have revolutions per minute, but in their case these indicate the number of times the crankshaft can turn.
Revolutions per minute also express angular velocity, that is, the number of turns completed each minute by a body or part rotating around an axis. This parameter is usually written as rpm, RPM or R.P.M. This measure does not belong to the International System of Units, so it is sometimes advisable to accompany it with units that do belong to this system, such as min-1, Hz or rad/s. In the case of rotary machines and tools, it is most common to find it followed by the abbreviation Hz.
Drill speed
A drill, whether a hammer drill, a cordless drill or a large machine like those used in machine shops, consists of a head to which a drill bit is fitted. The drill bit is the cutting tool of drills and is used for machining by metal cutting. Drills are used to drill holes and, to do so, the bit approaches the surface of the workpiece while rotating and enters it at high speed, removing the surplus material. But the rotation of the bit is produced in the head or spindle in which the bit is mounted, and it is the rotation of the spindle that makes the machining possible.
There are different types of drill in industry. Each has its own unique characteristics, and this includes the speed the drill can reach. Drills, which are indispensable in all machine shops and carpentry workshops, are classified as follows:
- By power source: corded electric, battery-powered or cordless, and pneumatic or air-powered.
- By the work to be done: screwdriver drills or non-percussion drills, hammer drill, angle drill, pillar drill and magnetic drill.
Of the machines described above, the pillar drill and the magnetic drill are for professional use and are used to machine parts in series in machine shops and factories. The other types of drill are used for simpler tasks and even for DIY.
How to choose a drill
If you are looking for a drill for your workshop or simply for some DIY job, bear in mind certain parameters before choosing the tool.
Drill speed
Drill speed is one of the most important aspects of this tool. The rotation speed of the bit varies depending on the type of machine chosen, but it can range from 800 to 3,000 rpm. Drills with higher revolutions per minute are much more effective in materials such as steel. This means the highest speeds are intended for machine shops where different types of metals such as steel and iron, among others, are worked.
Percussion rate
The percussion rate is only found on some types of drill and refers to the number of blows the bit can strike on the workpiece. To work very hard materials, the drill must deliver at least 4,300 blows per minute. Drill speed, as well as percussion rate, is essential when choosing a good tool.
Power
Power is measured in watts (W) and varies between drills, ranging between 500 and 1,300 W. This indicator is taken into account when you want to buy a corded drill. In cordless drills, power is measured according to voltage (V) and battery capacity (Ah); if you want to buy a drill for DIY and simple jobs, a drill of 10.8 to 18V will be enough.
Drilling capacity
This indicator tells you the maximum diameter that can be drilled. It indicates the performance of the tool.
Chuck type
The cutting tool is held in the chuck: drill bit, screwdriver bit, etc. Chucks can be conventional (they use a key), keyless and SDS.
Battery type
When buying cordless drills, the battery plays a very important role. Today there are three types: Ni-Cd, made of nickel and cadmium; lithium, which is very light but expensive; and NiMH, or nickel metal hydride, which has a memory effect and is very heavy.
Frequently asked questions
What are the revolutions of a drill and how are they measured?
They are the complete turns the drill bit makes about its own axis in one minute, and are expressed in rpm (revolutions per minute). They indicate the angular speed of the head or spindle in which the drill bit is fixed. As it is not an SI unit, it is sometimes accompanied by min-1, Hz or rad/s.
How many revolutions per minute does a drill reach?
It depends on the type of machine, but the rotation speed of the drill bit can range from 800 to 3,000 rpm. Drills with more revolutions are much more effective in materials such as steel, which is why the highest speeds are intended for machining workshops that work metals such as steel or iron.
What types of drill are there and which are for professional use?
By power supply, there are corded electric, battery-powered and pneumatic drills; by job, screwdriver drills, hammer drills, angle drills, pillar drills and magnetic drills. The pillar drill and the magnetic drill are for professional use and are used to machine parts in series in workshops and factories; the others are intended for simpler jobs and even DIY.
What else should you look at when choosing a drill, besides the revolutions?
You should look at the percussion rate, if it has one, which for very tough materials must be at least 4,300 blows per minute; the power, from 500 to 1,300 W in corded drills, or the voltage and battery capacity in cordless ones; the drilling capacity, which indicates the maximum diameter; and the type of chuck: keyed, keyless or SDS.
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