Do You Know the DTH Drilling Method?

Nov. 30, 2023

In DTH drilling, the drill string rotates while the drilling hammer continuously strikes down into the rock. Inside the hammer, a piston-powered by compressed air gives the drill bit its striking power. This combined with the rotational movement means the rock is crushed in a very efficient manner.

Because the power transfer takes place down in the hole when the piston strikes directly at the bit – hence the drilling method’s name – there is minimal energy loss along the drill string and holes can be drilled down to 6,000 meters in depth. DTH is a reliable method that drills stable holes with exceptional straightness.

DTH Drilling Rig

How does it work?

Down-the-hole drilling is to drive the hammer behind the drill bit by compressed air via the drill pipe. The piston strikes the bit directly, while the hammer external cylinder gives straight and stable guidance of the drill bit. This makes the impact of energy is not lost in joints and allows for much deeper percussion drilling.

Furthermore, the impact force acts on the rock at the bottom of the hole, which is more efficient, and straighter than other methods of the drilling operation.

And DTH is more suitable for the big hole of hard rock drilling, special for rock hardness over 200Mpa. However, for the rock below 200 MPa, it will not only energy waste, but also in low drilling efficiency, and serious wear to the drill bit. It’s because while the piston of the hammer strike, the soft rock cannot absorb the impact completely, which seriously lower the efficiency of drilling and slagging.

The method is also excellent both environmentally and socially because it produces far less noise and vibration than many other drilling methods, making it a widely used drilling method in cities and other populated areas.


Down the hole (DTH) drilling applications

● The most suitable hole diameter is 100–254 mm, in special applications can be up to 2M And the minimum can be around 50 mm as well.

● Theoretically drilling depth is limited by back pressure only (can be up to several kilometers).

● Adapt to hard rock and rock formation conditions.

● Mainly use pressurized air for slag flushing, and sometimes air foam for special application.

● Highly efficient in hard rock drilling.


Find the best DTH drill rig

DTH Drilling Rig


Jinke JK730-2 crawler mounted automatic rod exchange DTH drill rig is a hydraulic DTH drill rig. It is equipped with an automatic rod changer for rod storage, changing and connecting automatically, as well as hole locating device and luxurious cabin. A safe and comfortable operation environment substantially reduces labor intensity and curtails labor numbers. In contrast to the all-in-one rigs, JK730-2 is featured for its convenient operation and maintenance as well as low downtime rate. If you are interested in it, please contact us freely for more details!