A drilling machine is a machine tool used for making round holes on workpieces by feeding a rotating cutting tool called drill bit. Although the primary purpose of a drilling machine is to drill holes, depending on the type of machine it can also perform the following cutting operations.
What are the different types of drilling machines?
1. Portable drilling machines
Portable drills are hand-held machine tools used for drilling. These power tools that offer excellent mobility. Depending on the power source, there are two types of portable drilling machines; cordless and corded.
A cordless drill is one of the most popular power tools today. They are used for drilling holes and driving screws. These battery-powered cordless drills are highly portable and can be used in tight workspaces. Cordless drills are used by both DIY enthusiasts and professional due to its flexibility and ease of use. Apart from the regular cordless drills, there is also hammer drills and impact drivers; both offer additional force to the rotational motion of the drill. You can learn more about the difference between a cordless drill and an impact driver here.
Corded Power drills
These are portable drilling machines that are connected to the power source using electric cables. The corded version has its advantages and disadvantages,
Pros: They offer more power since they are connected to the regular power supply. You will not run out of battery power and there is no need to carry extra batteries. The continuous supply of power ensures the steady performance of the drilling machine. On the other hand, a cordless drill may show a drop in performance as the battery drains. And finally, the corded drilling machines usually cost less compared to the cordless version.
Cons: On the flip side, the electric cable on the corded version provides less mobility compared to cordless drills. The cord may cause hindrance especially when you are working in tight spaces. When you are working in vast construction sites it may not always possible to get the power supply through long cords. In addition to that, the electric cables possess the potential risk of electric hazard, particularly on a busy job site.
Fixed Drilling Machines
2. Sensitive Drilling Machines
These are small and precision drilling machines used for accurate jobs. The primary characteristic of this type of drilling machine is the absence of auto-feed; in other words, the drilling is done manually using a hand lever. When you drill the hole, you can feel the pressure on your hand and hence the name sensitive drilling machine.
These drilling machines are usually designed to drill holes from Ø1mm to 13mm (1/64” to ½-inch). The sensitive drill press is equipped with friction drive mechanism and self-centering chucks. This enables the machine to hold a wide range of drills bit sizes and adjust the speed accordingly. The rpm of this type drilling machine is generally in the range of 400 to 8000 revolutions per minute.
The sensitive drilling machines can again be divided into two types; bench drilling machine and floor drilling machine.
Bench drilling machine: These are small light duty drilling machines that are mounted on a bench or table.
Floor drilling machine: These are slightly larger machines and fixed on the floor. They can accommodate larger workpieces with more height.
3. Upright Drill Press
This is the big brother of the sensitive drill press. They are similar in construction; however, they are equipped with auto-feed and have higher capacity. The table of upright drilling machines may be moved along lead screw to move the positions of the holes precisely.
4. Radial drilling machine
A radial drilling machine consists of a base, main column, a radial arm and the drilling head with a motor that can slide along the radial arm. The radial movement of the arm along with the linear motion of the drill head ensures the position of the cutting tool precisely.
Radial drilling machines are used for drilling holes, tapping, reaming and boring large and heavy workpieces. They are heavy duty machines that can accommodate heavy jobs (think large machine parts etc.) that cannot be easily moved around on an upright drill press or even a milling machine.
How does it work?
- First, you should load the workpiece on the table on the base of the machine. Use T-slots in the table to clamp the work with t-bolts and flat clamps.
- Mark the position to be drilled on the work-piece.
- Move the radial arm up or down along the round column of the machine to adjust the z-height. On most machines, the up/down motion of the radial arm is motor powered.
- Rotate the radial arm and move the drill head along the radial arm to accurately position the drill bit above marked position.
- Lock the radial arm and the drill head in position before you start drilling.
- Finally, rotate the hand wheel or use the power feed mechanism to bring down the drill bit into the work to drill the hole.
Radial drilling machines are available in three different versions; the regular one, semi-universal, and universal radial drilling machine. On a universal drilling machine, you can tilt the drilling head to drill at an angle.
Special Purpose Drilling Machines
5. Gang Drilling Machine
In this type of drilling machine, a series of single spindle drilling machines each of which can perform different operations are connected together on a common base. Each spindle can be set to different speed, feed, and depth independently.
A gang drilling machine is very useful in mass production and assembly lines where the part is moved stage by stage to perform different operations. For example, the first spindle in the gang drilling machine could be set to do center drilling, the second spindle to do the drilling, third one to do countersinking and a fourth spindle for taping the drilled hole.
With the help of suitable jigs and fixtures fixed on the drilling machine tables, you can get high repeatability. You could make use of automation or robotic arm to carry the workpiece from fixture under one spindle to the next easily to speed up the production.
6. Multi-spindle drilling Machine
Multi-spindle drills have more than one spindle on a single head. Unlike a gang drilling machine, the multi-spindle drilling machine completes all the operations in a single pass. These types of machines are used when a large volume of components that require accurate hole positions with excellent repeatability. For example, threading of holes in a stamped component.
Usually, these multi-spindle heads are custom made as per the distance between the holes in X and Y axis. Since the coordinate between the holes never changes, you will get high repeatability.
7. Turret Drilling
A turret drilling machine will have multiple spindles called turrets which can hold different tools. However, unlike a multi-spindle drill press, only one spindle will be active at a time. Once a tool finishes its desired operation, the turret head will be indexed to bring the next tool to the drilling position and the cycle continues.
8. CNC drilling machines
9. Deep Hole Drilling Machines
As the name suggests these are special purpose drilling machines specifically designed for making extra deep holes. Depending on the type of job you may want a vertical or a horizontal deep hole drilling machine. This type of machines is valuable in injection mould making where you have to drill deep holes to make cooling holes.
Other Machines that can be used for drilling holes