Ever encountered any problems when core drilling using a small diameter into reinforced concrete?
Maybe the crown or tip wears down too fast? Seems like it is not drilling? The crown breaks off? Hit steel and nothing is happening?
In this blog we will try to give you some solutions to the above problems to help you in your next project.
Firstly, to clarify, we will be talking about 12mm to 24mm Diameter range and may apply for similar sizes also.
A quality concrete core drilling machine is essential too. One with a high rpm works best for these smaller sizes. Around the 2000 rpm is recommended. Hand held drilling is ok for smaller depths to be drilled, however rig mounting is ideal especially if cutting through reo is required. Brands such as Husqvarna, Diamond Tool Industries and Weka come to mind.
When using a rig mounted model, a guide is guaranteed to ensure accurate drilling and eliminate any wobble, flexing of the core barrel. These guides usually come with the core drill rig.
When drilling, start at a high rpm and do not force the drilling process. Apply slight pressure however let the drill do the work. Make sure correct water pressure is used as this really plays a part in the cutting process and will make the process a whole lot easier.
It is the grit from the slurry combined with the diamond impregnated diamonds that provide the cutting process.
Note: Too much water flushes all this away and will not cut the core effectively and not enough water will cause the diamond segments to heat up and ‘glaze up’ which in turn will not provide a cutting process.
If you are drilling to a depth and hit reinforced steel, simply reduce the rpm usually by changing to a slower speed and let the machine do the work. Again, do not put excessive pressure on the drill.
Once through the steel, change gear up to the higher rpm and keep going to the required depth.
Because these are smaller diameters, yes they will wear quicker than say a 50mm diameter. Obviously, it all depends on the mpa of concrete, reinforced steel diameter etc.
It is recommended to drill the hole entirely using the concrete core drill barrel. Some have tried to drill their required hole using a masonry drill until they hit steel, then use the core drill bit to drill through the steel. Unfortunately, as mentioned above, the process requires the slurry grit to aid in the cutting process.
To sum it up, no one likes drilling these smaller diameters especially when you have to drill a 14mm diameter hole and go head on at a 16mm steel reinforced bar! With the right equipment, process, water pressure, machine speed and knowledge life becomes easier. Good Luck and happy drilling!