A customer recently shared this photo with us — an R32-43mm thread button bit after finishing a round of blast hole drilling on a tunnel project through hard granite. We thought it was worth showing, because the condition of a used bit tells yo...
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A customer recently shared this photo with us — an R32-43mm thread button bit after finishing a round of blast hole drilling on a tunnel project through hard granite. We thought it was worth showing, because the condition of a used bit tells you more than any spec sheet ever could.
KAIQIU R32-43mm Thread Button Bit after drilling in granite
The Job
Tunnel face drilling in granite. If you have worked in underground excavation, you know what that means. Granite chews through ordinary bits fast — high compressive strength, heavy on quartz, and it does not forgive weak carbide or poor heat treatment. Blast holes need to go in clean and straight, shift after shift.
The contractor was using our R32-43mm bits on a standard top hammer rig with the usual water flushing setup. Nothing special about the rig or the parameters — just a tough rock and a bit that needed to hold up.
What the Bit Looks Like Now
Take a close look at the photo:
All buttons still there. Not a single one chipped or cracked. For granite, that is not a given.
Wear is even across the face. No odd grooves, no one side wearing faster than the other. That means the buttons were seated right and the load distributed as it should be.
Body held up well. You can see some marking from cuttings flow, but no deep wash or erosion. Threads are in good shape too — no deformation from the impact.
Flushing holes still clear. No clogging, which matters more than people think. A blocked flushing hole leads to uneven cooling and early button failure.
The bit is still usable. The project got more meters out of it than they budgeted for, and the penetration rate stayed steady right through.
Why It Worked
There is no secret sauce here. A few things we do differently:
The carbide grade is matched to hard rock — not a universal grade that is "good enough for everything." Heat treatment on the body is tuned so the steel stays tough without getting brittle.
The R32 system itself helps too. It is a proven thread profile for tunneling — good energy transfer, reliable coupling, and rods are easy to find anywhere.
What the Customer Said
The site supervisor told us: "We have tried a few brands on this granite face. These lasted longer and the buttons did not chip — that was the main thing for us. We are sticking with yours."
That is the kind of feedback we work for. No dramatic claims, just bits that do the job and last.
For Your Project
We make R32 bits from 43mm up to 76mm, plus the matching rods, couplings, and shanks. If you are drilling in hard or abrasive ground and want to bring your cost-per-meter down, we would be happy to talk through what works for your conditions.
Taizhou Kaiqiu Drilling Tools Co., Ltd.
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