When diamond core bits function predictably, a controlled material erosion cycle is established. Working in this manner, old diamonds peel away and new ones are exposed. In a way, this is a self-sharpening tool bit. Sometimes, however, the erosion rhythm stops, the core bit dulls, and the cutting surface becomes badly glazed. What’s going on? Before thinking about sharpening options, it sure would be nice to know why that coring tool is losing its bite.
When Good Diamond Core Bits Go Bad
Several factors can inhibit the matrix erosion effect that keeps diamond core drill bits sharp. A change in water flow might be retarding the exposure of good diamonds. If the material being cut is super-dense, good diamonds fall out before they can become worn. Even softer materials and loosely bound aggregates can disrupt the erosion process, leaving the core edges blunt and glazed. Of course, a good drill operator knows how a diamond bit will behave when it’s used on different mediums. He knows whether to adjust the cooling water, whether to increase the drill’s RPMs, and he knows when the diamond exposing rhythm isn’t operational. All the same, this is a known system flaw, so there should be a way to correct the issue, should the bit end up going dull.
Can Diamond Core Bits Be Sharpened?
There’s the question, one that has arisen because the erosion cycle has floundered. Well, assuming the drilling parameters have somehow gone awry, the bit is no longer carrying out its duties. First off, the drill bit isn’t really blunt; there’s a new layer of matrix-bonded diamonds sitting just below the glazed layer. We just need to strip away the dulled, worn diamonds and expose the sharp gems. Then, with the dulled crystals gone, the erosion pattern can be reestablished. A special cleaning stone or a wired brush should be packed in with the drill, perhaps in a recessed pocket. Using those abrasive tools, the covered up diamonds are exposed, the worn crystals are pulled away, and a diamond core drill bit is restored.
This is a hallmark of diamond cutting tools. The recovery method can’t be used on other drill bits. Because a new layer of diamonds is hidden below a worn surface coating, all we need to do is give the tool a little help. We do so by cleaning the worn material away and exposing the sharp diamonds. Again, that’s normally an action that takes place automatically as the drill bites down. If, for whatever reason, this cycle is broken, a manually wielded abrasive tool will soon scoop out the glazed debris.
