Core Drilling Guide Part 1: Introduction to Core Drilling

Are you ready to obtain the best drilling results for your project? If so, you need to determine what kinds of diamond bits or drills are perfect for the job. This is important since knowing the right tools to use will save you both time and money.

To which category do you belong? Are you a novice, an experienced engineer, hobby enthusiast, researcher, or a contractor? Knowing this will help narrow down your choice to the types of diamond bits that are most appropriate for completing your project.

To ensure that everything goes smoothly, take heed of these three prerequisites to core drilling success:

  • Proper detailing
  • Suitable preparation
  • Following basic techniques

Type of Material

What kind of material are you working with in your core-drilling project? What are its features or characteristics? This will help in determining the tools and techniques you’ll need to obtain the desired outcome.

The kind of material you are planning to drill is an important consideration in your choice of drills:

a) Hardness of Material

For ultra-hard Alumina, Sapphire, natural/precious stones, materials with high metal content and advanced ceramic; metal bonded sintered diamond drills are the best.

For less expensive or softer materials such as tile, soft stones, glass, and composites, nickel bonded electroplated diamond drills work the best.

The basic rule for core drilling is that you will require soft bonds for hard materials, for free and fast drilling. Similarly, abrasive or softer materials require hard bonds for long-lasting performance.

b) Cost of Material

What kind of material are you going to drill? Determine how expensive it is. For expensive or precious material, the cost of the bit or drill matters little.

The use of a diamond thin wall core drill will help minimize deformation and loss of material. Having an estimate related to per-hole quality and target cost surely helps.

c) Density & Geometry of Material

Each type of material has a specific composition, density, and hardness. A method or technique that works for one, may not work for the other.

If you are looking for optimal, consider custom diamond drills that suit perfectly the type of material you’re planning to drill.

Material properties such as brittleness, size, shape, hardness, and diameter, will help in your choice of bits, clamping methods, feeds, speeds, and drilling equipment.

d) Thickness of Material

The thickness of the material you’re drilling determines how much pressure and coolant to use.

Multiple direction coolant works the best with through the drill, coolant submerged drill, and from the sides. This ensures enough lubrication and coolant will reach the drilling zone.

Running the coolant at high pressure through the diamond bit/drill centre using a swivel water adapter is ideal for drilling a material thicker than 1 inch or 25.4 mm. With, long-depth drilling you will require a stepwise mechanism using multiple bits or drills.

Core Drilling for Reinforced and Non-Reinforced Concrete Surfaces – An Overview

Reinforced and non-reinforced – both types of concrete surface are often encountered in highway drilling and construction applications. Both require unique drilling methods and also differ in drilling results.

For instance, drilling through steel bar produces a different sort of pressure and therefore, has a different wear on the cutting surface. Thus, it is important to determine the type of concrete surface first and then choose the right drilling equipment that will perform the job efficiently.

What is Core Drilling?

Core drilling is one of the most effective, non-vibratory ways of drilling through reinforced and non-reinforced concrete surface. It creates holes without causing aggressive demolition or too much strain.

The core drill is a highly efficient and powerful tool for boring holes through reinforced concrete, block, brick, masonry, and stone.

The typical core bits are made of hollow steel cylinders that are fitted with segmented diamond teeth. The teeth grind away the concrete surface for creating a hole of any desired size.

Usually, core bits vary in size from 3/8” to 14” in diameter. Most core bits are capable of drilling through 12” and even more. However, longer extensions, threaded barrels and bits are also available.

Diamond drilling is essentially preferred.This is how to get neat and clean holes through all types of reinforced and non-reinforced concrete, block work and bricks. The core drilling procedure is most effective in getting precise and accurate circular cuts through varied concrete surfaces.

Benefits of Core Drilling

The significance of core drilling is unparalleled. Unlike traditional drilling procedures, diamond drilling is more comprehensive in nature and environmentally sound. Discussed here are some of the key benefits of core drilling:

  • Core diamond drilling is most efficient where precise circular cut and neat holes are required
  • The drilling method can be equally used for reinforced as well as non-reinforced concrete surfaces
  • Drill holes of virtually any diameter to make openings for electrical, plumbing, and HVAC installation
  • Core drilling can also be used for studying and analyzing rock, structures, and strata
  • It produces less vibration and strain as compared to conventional methods, thus, causing minimal structural damage
  • Use core drilling procedure for increased accuracy and minimal labor cost

Drilling Reinforced Concrete Surface

Drilling through reinforced concrete surfaces can be difficult and takes longer than other concrete and allied material.

For this, the core drilling procedure is adopted.This is where the steel bar of reinforced concrete is drilled through by fine diamond crystals in a machining mode. However, it puts a high strain on the diamond core bit as steel is a relatively ductile and very tough material.

When the core bit rotates against the same section of drilling surface, it encounters concrete that’s more brittle than before. This facilitates loading and unloading of diamond crystals and bond materials.

Drilling Non-reinforced Concrete Surface

Drilling through plain concrete is relatively different from that of reinforced concrete. However, the core drilling method can also be used in cutting holes of any diameter through non-reinforced concrete surfaces.

Here, the concrete material is removed or drilled through the process of crack propagation. Diamond in the core bit generates stress on brittle non-reinforced concrete that creates a crack on the surface.

The cracks are caused when the concrete is broken away from base material, allowing the core bit to drill through the material efficiently.

Tips for Core Drilling

Core drilling can be used for both reinforced and non-reinforced concrete surfaces, delivering increased accuracy, precision, and efficiency. Here are some valuable tips for core drilling that will help you save time and money, and improve the drilling results.

1. Water – If you are using a wet diamond core bit, it is preferable that you use little water. This enables the diamond to grind away the concrete surface efficiently. Excessive water pressure can wash away concrete grit, preventing the diamonds from becoming exposed. To get effective results, apply little water only till the slurry resembles that of creamed coffee. Appropriate slurry helps in the grinding process and also keeps the core bit cool. The diamonds remain exposed all through and stay in contact with the slurry particles.

2. Vacuum Base – Base vacuum can be used while drilling through concrete surface that is smooth. However, make sure that the gasket is in good working condition. Also, do not use a vacuum base while drilling through ceiling or walls.That can be dangerous. Ensure that the vacuum filter bottle has no debris or water inside as it can harm the vacuum. Also make sure that the vacuum pressure is just adequate for the drilling purpose.

3. Diamond – To get best results and also save time and money, it is important to choose a diamond type that matches the application. For this, it is imperative to consider the material to be drilled and particular diamond bond specifications of the core bit. Too soft a bond may wear away the diamond prematurely; too hard a bond may increase drilling time. For reinforced concrete, choose a soft diamond matrix; for softer materials, choose a hard diamond matrix for effective results.

4. Pressure – For efficient drilling through reinforced and non-reinforced concrete surface, maintaining steady and even pressure is most important. The right amount of pressure ensures maximum life of the core bit. Too little pressure than required for the application can cause the diamond to glaze over, while inconsistent pressure can cause the drill to glaze over. On the other hand, too much pressure can overload the drill, causing significant damage to the drill motor and core bit.

5. Speed – To grind through surfaces efficiently and prevent glazing diamond segments, it is important to set the motor at the right Revolutions per Minute (RPM). It is only at ideal surface speed, which is dependent on core bit diameter that you can cut through efficiently. For instance, smaller diameter core bits require higher RPMs.

6. Power – To achieve the right drilling speed, it is imperative to have adequate power. If the drill is underpowered, it can cause overheating during drilling, thus, damaging the equipment. When the equipment receives too much power, it can also cause increased abrasion and glazing of diamond segments.