Miners around the world extract natural resources such as coal, oil, gas, metals, precious stones and salts. The construction of tunnels, pipelines and wells are also part of modern mining. Just like working in quarries. Whereas in the early days, primitive tools were used to dig for natural resources, today high-tech structures, equipment and tools are used for mining.

Drilling tools as an important part of mining

The drilling tools, which break the rock and remove it in chunks, play a fundamental role in the process when, for example, blasthole drillings, drillings for pipelines or new shafts in mines are created. For the various applications, roller bits are often used for larger diameters. These usually consist of three movable rollers. The latter rotate and press against the rock. In this way, the rock particles are gradually broken out.

The use of drill bits has also already proven itself in the mining sector, especially for smaller diameters. In combination with the corresponding holder and the machine, they work on the same principle as a hammer drill.

What both types of tool - roller bits and drill bits - have in common is that their base bodies made of steel (cold work steel, alloyed heat-treated steel or special steel) are fitted with carbide bit inserts to break even extremely hard rock. This is because the bit inserts are literally at the forefront when it comes to creating the various cavities in the different types of rock and soil.

Edit the seats of the bit inserts with μm precision

In order to ensure process reliability in mining, great importance is placed on the high-precision production of tools. Drilling tool manufacturers therefore machine the seats for the bit inserts for mining with μm precision. Mapal has developed the Rockbit-Drill made of solid carbide especially for this application. In combination with the Mapal hydraulic chuck, customers machine the seats for the bit inserts with high precision.

The Rockbit drill has an innovative coating that ensures high wear resistance and therefore a long service life. Specially designed flutes ensure optimum chip evacuation. Thanks to its four-bevel geometry, the tool produces optimum bore quality in terms of alignment and positioning accuracy. The Rockbit-Drill is available with a point angle of 141˚ for machining the drill bit seats and with a point angle of 180˚ for machining the roller bit seats.

Use in practice

A Mapal customer is successfully using the Rockbit drill with a diameter of 16 mm for its drill bits. The manufacturer produces the drill bits from low-alloy steel on a machining center with an HSK-A63 spindle. The drilling depth is 1xD to 1.5xD.

The cutting speed is 80 m/min, the speed is 1,600 ^min-1 and the feed rate is 0.2 mm. The Rockbit drill reliably machines 1,618 holes. The customer is delighted: "With our previously used tool from a competitor, we only machined 600 holes." The customer was able to double the feed rate compared to the previous tool. And thus significantly increase the cycle rate. The Mapal tool also produces an optimum surface quality of_Ra (average roughness value) = 0.8 μm. The Rockbit drill impresses the customer across the board - both with the accuracy of the drill holes and the low burr formation.

The customer mentions another advantage that he achieves with the tool: Depending on the bore diameter achieved, different bit inserts are pressed into the base body. The mining tool manufacturer has various diameters of bit inserts in stock for this purpose. The greater the fluctuations in the bore diameter, the more different inserts he needs to have in stock. "Thanks to the high dimensional accuracy of the Rockbit drill, we can significantly reduce this variety of bit inserts and thus save costs. The drill holes are within a much narrower tolerance range," says the customer. Process reliability also increases. And: "We can achieve a higher degree of automation as a result."