Core Drilling

Core drilling can be a daunting task if you are unsure of how to go about it. With all the unknown factors that can arise, it is difficult for an inexperienced operator to know what they are getting into. There three factors that play a big part in helping you, they are water, speed, and power.


When drilling with a core bit, one of the most important factors to consider is water. You may think that the more water you use, the better, but this is not the case. Diamond core drill bits work by grinding away the concrete, water aids in the formation of concrete slurry when it mixes with concrete dust and debris. This slurry then helps with the grinding process by cooling down the core bit, additionally it will make sure the diamonds remain exposed by allowing the core bit to collide with particles in the slurry. Without the right amount of water, there is nothing to create the slurry, while having too much water will wash all the concrete dust particles away, leaving nothing to keep the diamonds exposed. In order to get the optimal amount of water, you should apply it slowly until the slurry colour changes to look like a heavily-creamed coffee.


One of the major factors in grinding properly and avoiding the diamond segments glazing over is your core drill motor’s rpm, which stands for revolutions per minute. Diamonds perform their optimal cutting at a predetermined surface speed, which is why every core bit should run at the proper rpm. If you have a large core diameter, you need to have a low rpm, whereas if you have a small core diameter, you will need to have a higher rpm.  Thankfully, these ratings are standard for almost all manufacturers in the industry. Most electric core drill motors have multiple speeds, so you can use different sized core bits and operate them at their appropriate speed. The table below can assist you in selecting the recommended speed for the core size you are drilling.

Bit Diameter (mm)2550751001502002503003504505006009001000
Recommended (rpm)3200160010508005304003202652251751601308575


Power is a very important factor in maintaining the correct drilling speed. Most core drills are electrically powered, and it is recommended that you use an amp meter when drilling with this type of core drill. You should try to push the drill motor to its maximum rated amperage but be sure not to exceed it. Going over the rated amperage of the motor will result in the motor becoming bogged down, which reduces productivity. Operating the core drill at a higher rate than its maximum amperage will cause the internal components of the electric core drill to overheat and wear down prematurely. This will increase your maintenance costs and may require you to replace the machine. The same principles also apply when you are using a hydraulic core drill motor. It is important to maintain the correct flow to ensure the correct rpm is used. Core drilling can be an intimidating task for anyone new to it, but by keeping these three factors in mind, you will be able to save both time and money by coring holes productively.


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