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Analysis of the reasons for rock drill bits “Broken body”and “lost teeth”
Release time:
May 07,2025
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The most troublesome problems in rock drilling operation are body broken and alloy loss, which not only delay the work schedule, but also damage the equipment and even lead to safety hazards. To completely solve these two problems, we must solve from the source of manufacturing, to ensure that every aspect of excellence!
1. body hardness: Neither too hard nor too soft is good , the key in the“just right”.
The body is like the “skeleton” of the drill bit, if the hardness is not suitable, the problem will come immediately:
Hardness is too high (such as HRC 50 or more): although wear-resistant, but easy to become brittle, when encountering impact or hard rock layer, it may be directly broken, like glass falling to the ground“click”broken.
Hardness is too low (e.g. HRC 35 or below): although not easy to break, but wear too fast, the hole of body will be worn out, the alloy teeth will not be able to be stuck, and ultimately lead to the “tooth loss”
The best solution: through precision heat treatment to adjust the hardness, generally controlled between HRC 40-45, to ensure wear-resistant, but not too fragile, like a good knife, both sharp, but not a crack!
2. Alloy inlaying technology: not enough precision? The teeth can't be mounted firmly!
Whether the alloy can be firmly fixed in the body, the key depends on the drilling accuracy and inlay process:
(1) The hole drilling must be precise, not even the slightest deviation is acceptable!
If the hole is crooked, wrong size, there will be a gap between the alloy teeth and the body, the teeth will be loose when working, and eventually fall off.
Our solution: the use of high-precision CNC machine to ensure that the position, angle, size of each hole is completely consistent, the error is no more than 0.02mm (thinner than a hair!).
(2) Hot inlaying process: let the alloy teeth and the body locked.
Ordinary cold pressing method: hard to plug in, easy to damage the alloy teeth, long-term using will be loose.
Heat the body (about 300℃), let the metal expand, the hole will be slightly larger.
Quickly load the alloy teeth, after cooling, the body shrinks, like an “iron hand” to hold the alloy teeth tightly, more firmly than glue!
And then after precision grinding, to ensure that the bonding surface 100% fit, completely avoid loosening.
3. Alloy teeth layout design: incorrect arrangement will lead to wasted efficiency!
The layout and angle design of the alloy teeth directly affects the life of the drill bit and drilling efficiency:
Hard rock (such as granite): adopt “staggered” tooth layout to reduce impact concentration and avoid chipping.
Soft rock (e.g. shale): adopt“dense tooth distribution” + negative front angle to improve cutting efficiency.
Special working conditions (e.g. quartz ): use spherical alloy teeth for better impact resistance.
4.Shape of alloy teeth: suitable tooth shape makes drilling more easily
Parabolic teeth: parabolic curved surface at the top of the teeth, similar to a “bullet head”, with a wider cutting edge.
Core advantage: high drilling speed + high wear resistance, suitable for continuous drilling in medium to hard rock.
Spherical teeth: similar to bullet teeth, but with a larger spherical radius and a wider contact surface.
Core advantage: Extremely strong wear resistance + strong resistance to partial loads, suitable for highly abrasive rock formations.
5. Human factor is also critical
Improper operation (e.g. too high rotational speed, too much propulsion force) will lead to overheating and accelerate wear.
Failure to replace worn teeth in time will lead to overloading of other teeth, triggering chain damage.
“Broken body” and “lost teeth” are not accidental problems, but are the result of a combination of material, process, design and use. Only by making the alloy body and alloy teeth fit perfectly like “gear bite” can they be both wear resistant and impact resistant, and really achieve value of each gram of precious metal! Henan Kings Rock Tools selects high-quality alloy, intelligent and high-precision hot treatment technology, optimizes alloy layout, and provides ultra-long-life bits through professional rock testing.
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