For a number of years Sandvik have been consolidating more features into fewer drill-bit models in order to widen each bit’s application range.
They have recently introduced two new products – the XT48 and Uniface. The XT48 is a new grade of cemented-carbide that has the highest coexistence of hardness and toughness seen in one tool. The Uniface comprises a series of three new, patent-protected universal bit-face designs, one for Ø51-64mm bits, one for 70-96mm bits and one for 102-152mm bits.
The Uniface design brings together, in a single drill bit, a range of features that formerly necessitated two or more different models. To qualify for the RT300-Uniface label, a drill bit must have both grade XT48 cemented-carbide buttons (indicated by the suffix 48 in the ordering number) and a Uniface front. Sandvik say that RT3000-Uniface bits are expected to add value through higher productivity, better blasting results and lower rock-excavation costs.
The guidelines for choosing the right Sandvik RT300-Uniface bit are: spherical buttons for very hard rocks; ballistic buttons for less-hard rocks; regular bit-skirt for solid homogenous formations; and Retrac skirt for mixed, jointed or fractured formations. The versatility of Sandvik RT300-Uniface bits means, however, their respective ranges of use are now much wider than before and the changeover boundaries are less strict.
All Sandvik RT300-Uniface Retrac bits feature a new stepped-splines Retrac skirt, designed to give the best possible hole-straightness and retractability in mixed and/or fractured rock formations. Since the long, splined skirt is stepped diametrically, bit rotatability improves immediately. Any gauge wear to the bit-face and bit-skirt is now more synchronous due to the steps on the skirt, and the skirt always has sufficient gauge to provide good guidance in the hole. Not only does this improve the long-term rotatability of the drill bit, it also reduces wear, cuts energy demands and provides better quality holes.
Sandvik RT300-Uniface drill bits combine the best features of the former Sandvik Flat-Face series of bits (for hard, abrasive rock formations) with those of the former Sandvik Drop-Center series (for mixed rock conditions and fractured formations). One characteristic is the high number of buttons in the face, as well as their optimal placement and larger dimensions.