ROCK TOOLS production of cemented carbide products, which is a complex powder metallurgical process involving many processing steps, such as raw powder production, mixing and milling, spray drying to produce granulates, followed by pressing, extruding or moulding into a soft green body having the desired shape. Densification of the green bodies into blanks involves debinding and liquid phase binding sintering. The final insert or button is obtained after several postsintering treatments, such as grinding and other finishing operations, which significantly increase the strength of the carbide insert.
Interestingly the shape of pressed and sintered inserts looks the same – but with the important difference that the sintered inserts have about 50 % less volume when it is sintered to full density. This shrinkage is a similar effect as seen when firing ceramics
PowerCarbide ® options are now available for top hammer, down-the-hole, rotary and mechanical cutting rock tools
and is very important in providing structural strength and hardness.
All manufacturing processes are linked, meaning that any change in any manufacturing step in the production chain will influence the subsequent process and the quality of the final product. Sandvik is well-known for high performing cemented carbide products and rock tools and at all Sandvik’ s production sites the quality control and tight tolerances are of most importance in every production step.
Martensson:“ Depending on the application, the carbides have distinct formulations – for top hammer and downthe-hole, you typically have quite small tungsten carbide grains with tight spacing, while for rotary you need larger grains and also more metallic binder to provide more toughness. Then once you get into mechanical cutting, we use very large tungsten carbide grains. It is always a tradeoff between wear resistance and toughness – if you want to increase wear resistance – primarily abrasion resistance – usually the toughness as crack resistance that goes down. With our premium PowerCarbide ® grades, we have been able to challenge this trade-off and achieve an increase in both the toughness and wear resistance, by optimising various properties as well as the manufacturing processes.”
This is unique to Sandvik and is a result of material and process design including solution hardening, mass transfer and reaction sintering. Sandvik has shown that PowerCarbide ® can reduce the amount of insert breakages by between 50-70 % depending on the application. At the same time, you get a wear resistance increase which translates to drill bit longevity.
Beyond that, what Sandvik likes to call the PowerCarbide ® toolbox, is the combination of new processes and material technology platforms, that allows it to pick and choose inserts for specific customer applications. None of Sandvik’ s competitors have any of these materials, so they are unique in the market and only available in
Sandvik bits. For customers they change bits less often, so they get better economy of drilling plus it is more sustainable. It also increases safety as changing bits manually comes with risk. In some cases, PowerCarbide ® means that the bits will last for a whole drill pattern resulting in that bit changes can be done away from the face before the next pattern, in a much safer place.
The grades within the toolbox – Self- Hardening( SH), Gradient Carbide( GC), Dual Property ®( DP ®) and XT – offer unique combinations of strength, hardness, toughness and wear resistance to optimise customer drilling applications. PowerCarbide ® options are now available for top hammer, down-the-hole, rotary and mechanical cutting rock tools with the specific grades including, GC81, GC85, SH69, SH70, SH75, XT49, DP ® 55, DP ® 65, XT90 and XT70. The geometry of the inserts varies as well – some are more rounded and some more pointed, depending on the application – this development is done together with the drill bit design teams.
GC81 and GC85 was developed for hard and abrasive ground conditions in top hammer and rotary drilling. Innovative manufacturing processes make it possible to produce inserts that are wear-resistant on the outside, while the centre provides a toughness that further extends service life. In top hammer GC81 has proven excellent performance in all types of abrasive rock, both surface and underground.
SH69 for DTH, SH70 for top hammer and SH75 for rotary and raise boring are grades with homogeneous properties throughout the material. It is‘ self-hardening’ as it has the ability to become both more wear resistant and tougher as drilling progresses. This is due to enhanced deformation hardening. The surface hardness is continuously‘ refilled’ which means that the hard top recreates during drilling. The hardening effect is greatest in hard and competent ground, and it works very well in pointy geometries with large protrusion as in Speedy bit and Autobit for top hammer applications.
XT49 takes the standard straight grade, XT48, to the next level. The manufacturing process enables the reduction of early breakages of the insert. As this grade is more resilient to breakage, it enables more protrusion and a sharper geometry.
The DP ®-grades, DP ® 55 and DP ® 65, were introduced in the 80’ s and are still the optimum choice in some applications, even if they have been and are successfully being replaced by the newer PowerCarbide ® concepts, GC and SH at most customers.
The XT70 is a grade perfect for cutting in hard and abrasive rock and offers the best high temperature wear resistance of all cemented carbide grades for longest pick wear life. The XT90 works at its best in hard to very hard but less abrasive minerals. It is also a snakeskin stopper and is the toughest cutting grade.
Finally, a note on circularity – also unique is that Sandvik controls the entire process from mine to final insert and drill bit – starting with scheelite tungsten ore mining at its Wolfram Bergbau und Hütten AG in Austria. At the other end of the scale, it has advanced recycling units for tungsten carbide, both in regional hubs in major mining areas as well as at customer sites, and a growing proportion of Sandvik’ s insert production is based on recycled material which reduces the amount of virgin ore having to be mined.
“ We work a lot with how to use circularity in a smart way – to be as sustainable as possible for example using recycled inserts but never at the expense of product performance. Recently, Sandvik introduced up to 75 % recycled material in most of its PowerCarbide ® grades, giving a large decrease to an already low carbon footprint, still with same or even improved performance proven in field tests,” said Kaar.
International Mining | NOVEMBER / DECEMBER 2025 51