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How to Sharpen A Dulled Core Bit

Nov. 15, 2021

Sharpening is also known as stripping. There is no easy, one-size-fits-all solution to sharpening a drill bit; it takes experience and knowledge. So in this blog I offer some advice and basic guidelines on how to sharpen your drill bits.

Diamond-impregnated core bits are self-sharpening, which means they are designed to stay sharp throughout the drilling process. Under ideal conditions, as the matrix wears, new sharp diamonds are exposed at a constant rate and dull or worn diamonds are released. However, if the drilling parameters are not set correctly or the coring bit is not the right type for the ground conditions, the diamonds on the surface of the bit may wear and it will stop working.

Possible causes

This can happen for two reasons.

The drilling parameters or settings you have selected are not suitable for the ground conditions. You should refer to the recommended parameters in the published documentation or view them here.

The core drill bit may not be suitable for the type of rock formation you have on the ground. Core drill bits are developed for specific hardness and wear levels. In addition, if the ground is variable, the core drill bit you start drilling with may not be suitable once you reach a certain depth. Make sure you have the correct type of core bit.

wire-Line Diamond Impregnated Bit

What you can do

Once this happens, it is necessary to sharpen or strip the core bit. This procedure involves removing a thin layer of matrix to expose the diamond so that the drill bit can start cutting again. There is no need to remove the coring bit from the drill hole, as this can be done by changing or adjusting some of the drill parameters while continuing to drill. It is important to note that this technique will consume your matrix and the amount consumed will depend on the experience, ability and responsiveness of the stoker.


Temporarily increase the drilling pressure (WOB) by 15% to 20%.

At the same time, reduce the water flow rate to near the minimum recommended by the coring bit manufacturer.

When you see a slight increase in WOB and a spike in rotational torque, these are signs that the matrix is being stripped and worn, exposing new sharp diamonds. The drill should begin cutting.

Immediately return the stream to its original volume and lower the WOB.

Try adjusting the parameters to a different drill setting than the one previously used to avoid a repeat of the problem.

Sharpening the core bits can be a tricky technique, so if you are unsure, you should call a technical support representative to help guide you. HANGHUA's technical support team has other tips and tricks that can be used to help maximize cutting potential. We're here to help you improve your drilling performance, so feel free to reach out by email.

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  • Tel. : +86 186 3217 4917
  • E-mail: wendy@hanghua.com
Hebei Hanghua Diamond Products Co., Ltd.
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