Various Types of Drills and their Functions
Drills are one of the most famous piece of any toolbox; the drill is invaluable in many manufacturing, maintenance, and repair jobs in industry, the workshop, and the home.
It is a rotating tool to which a cutting element or a drill bit is attached to make holes in wood, metal, plastic and other materials. For more reference, we have recently reviewed about the Top 4 Titanium Drill Bit sets of 2018.
Modern technology has advanced beyond the said basic functions to result in versatility. Thanks as well to the incorporation of various accessories or the design of new tool variants.
Today, therefore, a drill can also be used to screw and even unscrew fasteners, as well as sand, sharpen and grind surfaces—including mixing paint or mortar.
The drills have different models and applications; it can range from a simple, small corkscrew drill to an oil well drilling tower, covering disciplines as dissimilar as medicine or the aerospace industry.
In this article, however, we will only tackle the drills with the primary purpose of drilling holes.
Drive Drills with Driving Force
The incorporation of various forms of energy to operate the drills, particularly the electric motors, brought with it a revolution of comfort, efficiency, precision, and quality of the holes made. But not only that: it also gave them other functions, such as polishing, screwing or sanding surfaces according to the different types of drill bits or accessories attached to the drill.
Let's take a look at the details of the various drills driven by motive force, separating them according to their size.
A.) Portable Drills
Portable drills that work with motive force can be of two types: electric or pneumatic. And then, the electric drills are divided into two classes: corded electric drills and battery electric drills.
Electric drill with cable
It was the first electric drill and maintains its undeniable popularity to this day. It requires a constant supply of power from a power outlet, so it is compelling and provides ample torque. The most common design of cable drills is with a pistol grip which facilitates the use of the tool. Less well known is the right angle design, especially suitable for drilling holes in confined spaces where gun design has no place, and widely used by plumbers and electricians.
The electric drill with cable admits several types of drill bits and is intended for drilling wood, fiberglass, light masonry, metal, drywall, and plastic.
If you change the type of accessory, this drill can also be used for placing and removing screws (the latter if it has the reversibility function) and for sanding and polishing wood.
Cordless or cordless electric drill
It has a design similar to the drill with a cable with the difference that it works with batteries and is much lighter. The main advantage is the mobility it offers to the user, being able to be used in remote areas that lack a nearby electrical outlet. Since it is lighter than a cordless drill, it is easier to use and carry and causes less fatigue after heavy use.
The types of batteries used in a wireless drill are nickel-cadmium (cheaper and heavier) and lithium-ion (more expensive and lighter). Some manufacturers provide their wireless offer with lithium-ion batteries that are interchangeable among various tools in their catalog which helps save time and money.
Generally, a cordless electric drill is not as suitable for drilling in hard materials, such as masonry or thick sheet metal. However, it has excellent performance in wood, thin sheet metal, drywall, fiberglass, and plastic.
The perforations in hard materials have other protagonists of much better performance than the conventional drill and that work with a different mechanism: rotation and percussion (or impact). One of the tools that belongs to this category is the hammer drill which subjects the drill to a tapping action. It acts like a chisel, and as it rotates, it allows the hard material to be pulverized as it advances through it.
The hammer drill is particularly suitable for making holes up to 20 mm in diameter in steel, tiles, bricks, stone, masonry and unreinforced concrete. Available in both wired and wireless models, it is the perfect tool for the do-it-yourself enthusiast with the highest demands or occasional maintenance personnel.
When we need an even more powerful tool, massive and capable of drilling holes up to 50 mm in diameter, then we must look for a rotary hammer. Its operation is a combined movement of rotation and percussion. Only this time, the percussion is done by a pneumatic mechanism provided with a piston and a cylinder to produce greater hammering force.
Due to its high power, the rotary hammer is only produced in its cable version and is the preferred tool when it comes to drilling hard and reinforced concrete. For this reason, the typical user of a rotary hammer is even more demanding, such as a construction professional or an operator dedicated exclusively to concrete work, for example, the plates of dry buildings.
When the energy that feeds a drill is not electric but has compressed air then, we speak of a pneumatic drill.
Pneumatic drills don't look very different from electric drills, although instead of having a cable, they have a port to connect the compressed air hose, and are also available in pistol or straight handle designs.
Unless you have a compressor in your home, it is unlikely that a DIY enthusiast will be able to make use of a pneumatic drill.
On the other hand, this tool is much more common in mechanical or sheet metal and paint shops. For example, with the right accessories, a pneumatic drill could perform the following functions in a sheet metal and paint shop: stripping of resistance welding points, MIG/MAG spot welding to plug, drilling on plastic materials, or removal of paints, underbody protectors, putties and sealants, structural adhesive residue and embellishing moulding adhesives.
B.) Stationary Drills or Drilling Machines
In a field that encompasses more numerous, frequent, complex, rigorous and high-precision applications, typical of a workshop or an industry, portable drills give way to their stationary pairs, generally known as drilling machines.
Although they are mainly used to drill holes, when used with the right tool they can also perform some machining operations, such as reaming, threading, doubling, countersinking and grinding.
Vertical or Column Drill
These machines, also known as a drill press, pedestal drill or bench drill, are a type of fixed drill that can mount on a stand, or screwed to the floor or a workbench or table. The smaller models incorporate a magnetic base that holds the steel pieces to be drilled.
The machine consists of a base, a column (or pillar), a table, a spindle, and a drilling head usually driven by an induction motor. The head has a set of cranks (usually three) which are projected from a central axis and which, when turned by hand, move the spindle and mandrel vertically, parallel to the axis of the column.
These manually operated drills are often sensitive, and suitable for small jobs in wood, metal, plastic and similar materials, and are mostly intended for domestic use.
Conversely, non-sensitive vertical drill models with gear-driven heads that perform all these movements mechanically offer even more power and precision and are therefore suitable for workshops and small industries. In general, the drilling capacities of column drills range from 13 mm to 40 mm in diameter, depending on the model.
As the complexity and precision of a drilling job grow, the more sophisticated the drilling machines available in today's industry.
For example, for drilling holes between 25 and 40 mm in diameter with impeccable precision in high-quality steel and other heavy metals, radial arm drills are used, in which the arm can rotate around the column and move vertically, making this machine ideal for machining large parts.
Several highly efficient machines are available for serial industrial work: