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During the field research of the Powerbit Underground prestudy it was discovered that a quite common discard criteria especially for the 45mm HD bits was that the front buttons wore at such a high rate that they popped out thus making the bit only utilizing some 60-70% of the advantage of the HD gauge buttons. As the Powerbit Underground will further increase the amount of gauge carbide, it would have been an even bigger waste to keep the small front buttons.
It was also found that the penetration rate did not suffer so much from just the front button wear. Thus, it was reasoned that the Powerbit Underground equipped with Trubbnos buttons in the gauge, which increase ROP, would be able to boast HD buttons in the front without sacrificing the productivity of the drilling operation. This together with the fact that a spherical shaped front button loses the least amount of protrusion per drilled meter of all the button shapes sealed the deal for the Powerbit Underground button configuration which was subsequently deemed a success through multiple lab and field testing sessions.
One big challenge of designing smaller bits is to ensure sufficient material thickness all through the bit body. The buttons and flushing hole positioning is optimized to keep sufficient material thickness all throughout the bit body which is not an easy task for the designer. But thanks to the vast experience of the Epiroc R&D and the great properties of the Powerbit Underground steel the optimal design have been found.
Read more about Powerbit Underground here!