Underground mine development advances through a repeating cycle: drilling, charging, blasting, ventilation, mucking, scaling, support, and surveying. Together, these stages allow a drift, or development heading, to move forward round by round. Each stage must be completed safely and efficiently before the next round can begin.

The drilling stage directly influences productivity, equipment utilisation, and operating costs. While drill rigs and automation often receive much of the attention, the consumables at the rock face play an equally important role.

The drill bit determines how efficiently percussive energy is transferred into the rock, how well the rock is broken, how cuttings are removed, and how long drilling can continue before a bit change is required.

Robit’s Full Ballistic Extreme Carbide, or FBX, drifting bit has been developed for this balance between penetration speed and service life. The FBX bits are also now part of Robit’s new long-term agreements covering drilling consumables for Endomines’ Pampalo and Hosko mines in Finland.

Built for speed and durability
Drifting puts heavy demands on drilling consumables. Holes must be drilled to the planned pattern and depth, at a speed that supports the development cycle and with sufficient accuracy to achieve the desired blast result. Rock conditions may also vary considerably, even within the same mining area.

At the bit face, carbide buttons must resist abrasive wear while also withstanding repeated impact loading without premature breakage. Button geometry must support efficient rock fracture, while the bit face and flushing design must remove cuttings effectively. If broken material remains at the face, penetration rate can decrease, and heat and wear may increase.

The FBX bit is based on a full ballistic button design. Ballistic buttons generally provide a more aggressive contact profile than spherical buttons, helping concentrate impact energy into the rock and supporting higher penetration rates in suitable conditions. In the FBX bit, this geometry combines with advanced carbide technology intended to provide both wear resistance and toughness.

The layout of the carbide buttons and flushing holes has also been refined to support rock fragmentation and cuttings removal. In drifting, where drilling time is closely linked to the overall cycle time, these details can make a significant difference.

Tested in varying rock conditions
Robit’s reported test data for the FBX bits covers six test cases, including mining and tunnelling applications in Finland, France, the US, and Germany. The rock conditions ranged from soft, non-abrasive rock to very hard, abrasive rock.

In the test summary, the FBX bits showed performance gains in all six cases compared with Robit standard bits and competitor bits. The largest lifetime improvement was observed at a Finnish mine with hard, abrasive rock, where it reached 110%. Other reported lifetime improvements ranged from 20% to 71%, depending on the site and rock conditions.

The reported improvements in the rate of penetration (ROP) were more moderate but consistent. The highest ROP improvement in the test summary was 44% in medium-hard, abrasive tunnelling conditions in France. Other cases showed ROP gains between 15% and 25%. Robit has also reported up to a 45% faster rate of penetration compared with the company’s previous generation of drifting bits, and more than 30% improvement in average lifetime without regrinding compared with drifting bits requiring regrinding.

As with all drilling results, the figures depend on the application. However, the spread of test conditions is notable: gains were reported in hard abrasive, medium-hard abrasive, medium-hard non-abrasive, and soft non-abrasive conditions.

Drilling support for the Karelian Gold Line
Endomines is a Finnish mining and exploration company focused primarily on gold. Its Pampalo and Hosko operations are located along the Karelian Gold Line in Ilomantsi, Eastern Finland – a gold-bearing greenstone belt extending for more than 40 km.

Both Pampalo and Hosko include underground operations, while Pampalo also has an open pit. Robit’s agreement with Pampalo covers the direct supply of drilling consumables to Endomines. A second agreement has been signed with Veljekset Toivanen for the Hosko mine, where Toivanen is the main mining contractor.

The agreements bring Robit’s new FBX drifting bits into daily use at Pampalo and Hosko. The bit has been developed to improve both penetration speed and service life – two factors that directly affect development drilling efficiency. Longer intervals between bit changes also mean fewer interruptions in the drilling cycle and less manual handling underground.

Along the Karelian Gold Line, Robit’s drilling consumables help keep production and development work moving. With FBX, the focus is on a simple goal: faster drilling, longer bit life, and lower total drilling cost.

Applications

Drilling methods / services