Invented as early as 3000 BC by ancient Egyptian, a core drill, generally made of metal, is a hollow and cylindrical drill. It is used to make a hole into a surface or material and similar to a hole saw they are designed for removing a cylinder of any material. The drill tips are coated with carbide or diamond which makes them extremely hard to break and they are also resistant to high temperatures. The main difference between core drill bits and other cement cutting tools is that the core drill will extract a sample from the material.
Types of Material in Which Core Drill Bits Are Used:
There are basically three types of surfaces broadly in which core drill bits are used i.e. metal, concrete and masonry. Core drills used for drilling metal are known as annular cutters, when used in concrete they are known as diamond core drills which also need to be water cooled for using and for masonry, carbide core drills are generally preferred.
Other applications where core drills are used are:
- Rock and stone
- Granite and marble
- Hard Metals
Uses of Core Drilling:
- It is a jack of all trade and used for various purposes in industries. It is commonly used by construction professionals for a wide range of applications like building renovations and utility works which includes installation of drainage, sewer and water pipes, ventilation ducts and cables where usually large and deep holes are needed for installation.
- Core drills are also frequently used in mineral exploration where drilling and coring would go deep into the earth for lengths ranging from some hundred to several thousand feet. These samples which are extracted from deep inside the earth are then recovered and investigated by means of conducting experiments by geologists for finding stratigraphic contact points and mineral percentages.
Types of Core Drill Bits:
- Diamond Drill Bits: This is the most common of them all and comes in various shapes and sizes. But primarily there are two basic styles, blunt nose bits and core drill bits depending on the application of the diamonds; bonded and sintered. These are used on glass, stone, stained glass, ceramic tile, ceramics etc. Diamond drill bits have diamond tips that grind into even extremely hard materials.
- Carbide Tipped Drill Bits: These are used for drilling in concrete, masonry, and metals such as iron, cast iron and steel.
- Rotary Core Bits: These are used in drilling hole deep down. There’s a thing called barrel which is the hollow central part containing the core. Rotary core bits often comprise of two barrels – the inner and the outer ones, separated by ball bearings. This allows easy rotation of the core by the bit in the section of the inner barrel while the other remains stationary.
How to Know Which Bit to Use?
Drilling is most commonly used on wood such as fir or pine. If you use a superior quality steel drill bit for drilling wood, the hardness of the bit is approximately 80 times more than the wood. In case of carbide, it is considerably far harder compared to steel and if you use this in wood, the ratio of the hardness is almost ‘200 to 1’. Similarly, if you try to use a carbide bit for drilling in hard porcelain tile, the carbide drill turns out to be only about thrice as tough as the material that you are drilling. This low ratio of hardness that is,’3 to 1′ can help you understand the extent of a hardness of the porcelain tiles used nowadays. Therefore, while selecting a core drill bit the factor that plays a very important role is the relative hardness of materials.