Button and Insert Drill Bits
Threaded and tapered percussion bits with cemented carbide buttons, in flat, drop-centre and retrac face designs. Bit selection follows the rock, not the rig.
Features
- Spherical buttons last longest in hard abrasive rock; ballistic buttons drill faster in soft and medium rock and wear faster.
- Drop-centre faces improve hole straightness; flat faces give the highest penetration rate in homogeneous rock.
- Retrac skirts with reaming inserts allow the string to be pulled back through a fractured or squeezing hole.
- Gauge buttons protect the bit diameter, and gauge wear is what puts the hole out of specification rather than face wear.
- Bits are reground several times before discard, and the regrind interval, not the bit price, sets cost per metre.
Specifications
| Figure | Typical range | Unit | Why it matters |
|---|---|---|---|
| Bit diameter | 51 - 127 | mm | Set by the blast design and the explosive charge diameter. |
| Thread designation | R32 / T38 / T45 / T51 | Has to match the rod it screws onto. | |
| Button shape | spherical / ballistic / mixed | Matched to rock hardness and abrasiveness. | |
| Face design | flat / drop centre / retrac | Trades penetration rate against straightness and retractability. | |
| Number of flushing holes | 2 / 3 / 4 | Sets cuttings removal in wet and fine-cutting conditions. |