The Basics of Core Drilling
Modern core drilling equipment evolved from the mining industry that first used the techniques in the 1860s. Miners used these early tools to extract stone samples for mineral exploration work. Our industry changed in 1921 when Black & Decker launched the electric drill unit designed for contactors. Soon after this innovation, manufacturers designed drill bits that could be used for core drilling.
How Does Core Drilling Work?
The key to core drilling is the proper configuration of a power unit, stand, drilling bit, and safety equipment. The heart of the assembly is the core drill bit. These bits can drill a circle into hardened material, which remains in the drill bit and is pushed out after the drilling is completed. The bit is a steel tube that has a diamond matrix attached to its cutting edge.
The assembly’s drilling force can be supplied manually or with an assembly rig. The manual options are good for holes that are smaller than a 2” to 3” diameter, and about 4” deep. When plans call for larger diameter holes, or deeper penetrations, you should opt for a stand-mounted or rig-mounted assembly. These units also allow you to drill angled holes.
To aid in the drilling action and to prevent exposing workers to respirable silica dust, most assemblies apply water at the cutting zone. The water lubricates the area and reduces friction on the bit.
Who Uses Core Drills and for What Applications?Many types of contractors and engineers use core drilling equipment for many purposes. Core drill power units can be equipped with core tubes designed for a wide array of hard and soft materials. You can core drill through structural concrete, asphalt, stone, brick, and concrete masonry units.
The most common application is to add pathways in existing structures to allow for the addition of utility permeations, such as phone lines, electrical, cable and fiber optic openings. Plumbers and HVAC contractors use core drills to carve openings for electric heating, plumbing, electric wiring and hydronics.
Core drilling applications are also found outside a structure. Utility contractors use core drilling equipment in sub-surface applications such as adding laterals to manhole and vault taps, steam lines and freshwater piping.
Engineers, testing firms, and even some contractors use core drilling equipment to extract quality samples from pavement and foundations. These applications must follow the guidelines outlined in testing standards referenced by ASTM International (American Society for Testing and Materials) or other jurisdictions.
Residential contractors use core drills to create holes in foundations and masonry walls for dryer vent, fireplace, electrical and plumbing placements.
A less common application for core drilling is concrete removal. Line coring or line drilling is a technique by which you can remove a square or rectangle-shaped concrete piece by placing a succession of core holes in a row intersecting each other. The serrated edges allow you to break pieces away from the host concrete slab.
This method is often a last resort, as concrete saws and wire saws are much more efficient for these applications.
While manufacturers have designed their tools and assemblies to be easy to use, contractors should reach out for additional training resources.
Core Drilling Best Practices
Many contractors have found the information provided by the Concrete Sawing & Drilling Association (CSDA) to be useful. The CSDA membership is comprised of contractors, manufacturers and affiliated members from the construction and renovation industries. Their training programs include classes on core drilling, along with other topics such as sawing, selective demolition, cutting, and polishing.
Your local White Cap sales professionals are another important resource. Their knowledge of the local materials that will be drilled into, as well as the most current new product offerings, will enable you to configure the right core drilling assembly for your operations.