Sandvik develops new top hammer drill bit

Sandvik has created a new design for top centre drill bits.

According to the company they feature the largest upgrade to face drilling bits in decades.

Following field testing of the new bits, Sandvik recorded up to 80 per cent longer grinding intervals and up to 60 per cent long bit lives, which results in higher productivity due to longer service life, and a safer working environment due to fewer bit changes.

“The top priority when developing the new top centre rill bit was to increase service life,” Sandvik stated,” since the main reason for discarding a drill bit is excessive wear on the diameter, the simplest way to achieve longer service life is to add more gauge buttons.”

“However, this can prove problematic because of the minimal space available; furthermore an increase in the number or size of the carbide buttons generally decreases the penetration rate: the same impact force yields a lower net for per button.”

Sandvik believes it has now solved this problem with a ‘raised font’ elevating two or three front buttons – depending on the diameter size – by a few millimetres above the gauge buttons located on the periphery of the bit.

These front buttons are set at a slight angle relative to the symmetric axis of the bit, the raised front also creates a recessed hole bottom pattern that alters the rock breaking action to achieve improved performance.

In addition, the top centre bit also features a new cemented carbide grade, the GC80.

“The problem with carbides that exist on the market today is that they are either wear-resistant or tough,” Sandvik Mining top hammer tools product manager Robert Grandin said.

“When developing the GC80, we wanted to combine the best of those two worlds in order to get as much as possible out of the top centre design.

“The new bit design essentially delivers more drill metres per shift compared with a standard bit, thanks to fewer bit changes.”

The top centre drill bits are available in bit sizes 43, 45, 48 millimetres, with 2-3 raised end buttons and 7-8 gauge buttons in grade GC80 and connections R32, Sandvik Alpha 330, and R35.



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