What Is Core Drilling & How Is It Used in Construction?

Generally speaking, core drilling is the process of removing a cylinder of material using a hollow cylindrical drill.  Core drilling is used in construction industries, mining industries, geotechnical engineering and research.  Core drills are useful not only to cut a hole in material, but also in extracting material so that it can be examined.  The core drill has three main parts, comprising a motor, a handle, and the bit.

What Is a Core Drill Used For?

Concrete core drilling is a process used in the construction industry to cut a hole in concrete structures, floors, walls or ceilings.

Some of the applications for concrete core drilling include installing:

• HVAC ducts
• Phone lines
• Plumbing
• Sprinkler systems
• Reinforcements
• Tunnels
• Pipelines
• Parking garages
• Utility holes
• Manholes

The most common construction fields that may require core drilling include municipal projects, interior renovations, erecting new apartment buildings and bridge retrofitting, along with numerous other commercial or industrial projects.

How Does a Core Drill Work?

A diamond concrete drill bit is required for concrete core drilling. The bits for these tools are essentially steel tubes impregnated with pieces of industrial diamond. This drill is mounted onto the drilling machine’s shaft and then secured to the structure you are drilling into.

Once the core drill has completed the drilling process, there will be a concrete “slug” — the core — inside the drill bit that you can extract from the hole. This is accomplished by the drill’s hollow center, so it keeps the slug inside that defined area until removal. The core or slug can usually be examined to assess the stability or strength of the structure.

Core drills can also cut through several other materials besides concrete, including porcelain tile, limestone, rock, granite, fiberglass and even ice.

How to Use a Core Drill

1. Prepare the core drill and job site

Before actually operating the core drill, it is important to prepare the job site and ensure the drill is ready for use. You will want to:

• Check for alignment and possible binding of moving parts, mounting, and any other conditions that may affect core drill operation. Do not use the core drill if it shows any signs of damage.
• Read and fully understand the operating manual.
• Check the power supply’s flow and pressure output against the core drill’s requirements.
• Check for live electrical wiring near the work site or embedded in the material being drilled.
• If drilling through a wall, check both sides for possible obstructions.
• Before drilling through a floor, provide protection for all personnel and materials below the work area. Cores generally drop from the bit at the completion of the hole.
• Ensure all personnel is using the appropriate safety equipment.
• Clear the working area of all unauthorized personnel. Place barricades or secure the area so that no person can be injured.

2. Anchoring a core drill

A core drill can typically be bolt anchored or ceiling jack anchored to the floor or bolt anchored to the wall.

1. Measure the distance from the center of the anchor bolt slot in the base to the center of the drill spindle.
2. Mark from the center of the hole on the floor to be drilled to the spot where the anchor bolt hole will be drilled.
3. Drill and set the anchor bolt. Then place core drill over anchor hole and hand tighten the bolt.
4. Secure the core drill by tightening the anchor bolt.

3. Installing a drill bit

Before installing the drill bit, ensure that neither the bit nor the core drill is hot. What’s more, always make sure to wear protective gloves when handling, installing, and removing core drill bits.

Next, remove any dirt or contamination that may have accumulated on either the bit or drill spindle. Once you do that, you can begin to thread the drill bit onto the drill spindle and tighten it securely with a bit wrench.

4. Operating the core drill

Once you have done the steps above, you are ready to operate the core drill. During this process, you will want to do the following:

• Check the hole alignment by lowering the bit with the feed handle until the bit is about 1/2 inch from the concrete. It is important to ensure the bit is not resting on the concrete when starting the core drill.
• Make sure to always check the manufacturer’s recommendation for drill speed.
• Keep all body parts away from all moving parts of the core drill while in operation.

Wet Drilling vs. Dry Drilling

Depending on the application, workers may have to use either wet or dry core drilling.

Wet Core Drilling

Wet core drilling offers the greater efficiency of the two processes. Wet drills will typically drive the bit through the core faster than dry drill bits because the lubrication of the water helps loosen the material’s surface. Wet core drilling also leaves behind a cleaner, more stable hole surface because the water minimizes the dust produced during drilling.

Concrete, soft or hard brick, and reinforced concrete are materials best suited for wet core drilling. The process works well for applications like:

• Installing electrical conduit
• Plumbing work
• Running piping in masonry
• Air conditioning and refrigeration work
• Cutting into ceilings, walls and floors

Core drill bits that run wet will typically offer a longer life span than dry-running bits, as the water acts as a coolant for the heat produced during operation. The speed of the work itself also plays a role in bit durability.

Dry Core Drilling

Dry core drills look and operate very similarly to wet drills, but they use no lubricant. They will still remove the core in the same capacity a wet drill does. However, because there is no water involved, there is inherently more stress and pressure on the cutting blade, affecting drill speed and service life due to accelerated impact.

Wet core drills are often the preferred choice for many applications. If extra water is not necessary or may be hazardous for a particular job, then a dry core drill can be an acceptable choice. For example, if the work involves electrical wires, a dry core drill might be a better option.

One thing to remember about dry core drill bits is that the lack of water means there is more likely to be dust. You will need dust containment measures to ensure your operators and anyone nearby stays safe.

Advantages of Using Core Drilling

Using concrete core drilling for construction provides several advantages over other drilling methods, including:

• Less disruption: Core drilling produces less noise and vibration than a hammer drill, making it ideal for places like hospitals, offices and schools.
• Reduced mess and dust levels: Core drilling creates a smaller mess during the process, helping to protect operators and other people by reducing their chance of developing respiratory issues.
• Increased safety for surrounding structures: Core drilling enables you to maintain structural integrity and creates less risk overall throughout the process.
• Efficient, precise work: The core drilling process produces cleaner, more accurate holes quickly and effectively.
• Cost-effectiveness: Concrete core drilling requires fewer workers, allowing you to cut labor costs. Diamond concrete core drills are also extremely durable, meaning you can get extended life out of them.

What is Inverted Drilling?

Inverted drilling refers to the process of using a core drill to bore upside down through a concrete structure. Typically, this type of core drilling technique is used when there is no direct access from above a concrete structure or in the case where the holes need to be drilled beneath.

Construction workers and contractors often use inverted drilling for the following applications:

• Ceilings
• Walls
• Bridges
• Tunnels
• Road surfaces

What’s more, hydraulic core drills are better for inverted drilling jobs due to the ability of the operator to move freely with the tool. In addition, a hydraulic core drill can work even bore through concrete while submersed in water which makes it the perfect option for underwater inverted drilling projects.

Invest in a Core Drill to See Everything It Can Offer

Core drilling is an effective way to cut holes in challenging materials like concrete. In the construction industry, core drilling has applications ranging from installing HVAC ducts to setting up sprinkler systems. While you can use wet or dry core drilling to accomplish many different tasks, wet is often preferable in most applications.

With its minimal dust generation, noise and vibration output, and labor requirements, concrete core drilling is one of the easiest and most efficient ways to make a hole in a hard surface.

If you’re ready to take advantage of the benefits of a new concrete core drill, shop RGC Construction’s core drilling products to find the right model for your needs. You can also get in touch with our team to discuss your application or ask questions about how our core drills work.