How to Choose Crawler Mounted Pneumatic Tophammer Drill Rig?

You could need a drilling rig for a multitude of applications, for example to drill a well to access a natural resource (water, oil, geothermal energy, etc.), to build foundations, to make blasting holes in a mine, to take samples from the ground, etc.

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It is necessary to determine what the drilling rig will be used for, as well as what kind of terrain it will mainly be operating on. Depending on the terrain, you can choose between different types of drilling rigs: rotary drilling rigs, percussion drilling rigs, down-the-hole drilling rigs, top hammer drilling rigs (with high hammer), etc.

In order to make the best choice, it is important to determine whether the drilling rig will be used for your core business or for occasional operations, and in particular whether you want to take advantage of the latest innovations or whether a machine that has proven its worth over several decades might be suitable for you.

Safety, reliability and ease of use are also important elements to consider and are directly linked to each other. A machine that’s reliable and easy to operate, when used according to the manufacturer’s recommendations, increases user safety.

It is also important to define the type of mobility you will need. There are autonomous crawler drilling rigs and truck-mounted or trailer-mounted drilling rigs that need to be powered by a generator or the truck that carries them.

Once you have determined the type of machine you need, you can calculate the size required according to the diameter and depth of the borehole.

Drilling type Soil type Comments Rotary drilling Soft rock Significant depths up to 5,000 meters
Possibility of inclined or horizontal drilling Down-the-hole drilling Hard and cracked rock (limestone, granite, etc.) Depth up to 4,000 meters Top hammer drilling Consolidated land Small diameter (150 mm maximum), shallow depth
Able to do inclined drilling Auger drilling Clay, clayey sand, gravel Depth of a few dozen meters Core drilling All soil types Drilling for soil analysis
Able to do inclined drilling Percussion drilling Hard rock: sandstone, limestone, shale Depth up to 100 meters Pipe Jacking Clay, clayey sand, gravel Installation of horizontal or vertical pipes

Rotary drilling: This type of drilling digs a hole by grinding the rock with a tool under the effect of weight and rotation. It is mainly used in oil production. The cuttings are brought to the surface under the pressure of a drilling fluid that is injected into the drill string. Drilling fluid also helps consolidate the walls of the borehole, so it is not necessary to case it as the operation progresses.

Down-the-hole drilling (rotary percussion drilling or rotary hammer drilling): this type of drilling uses drilling rigs that drill with a rotary cutter (drill head) and hammer the bottom of the hole with a pneumatic hammer. The excavated material rises to the surface under the pressure of the compressed air used for the hammer. These drilling rigs are powerful and have high drilling rates, especially in rock. For artesian wells (wells where water naturally rises to the surface under groundwater pressure) or geothermal drilling, an air injection at the end of the drill pipe pushes the water up the borehole, allowing the operator to immediately determine the water flow encountered. This type of drilling is used for hard and cracked ground up to 4,000 meters deep. When the drilling bit is eccentric, the drilling can be done with a casing advancement system (installation of tubes by gravity) which reinforces the hole as the drilling progresses.

Top hammer drilling: this type of drilling uses drilling rigs that also operate on a percussion system, but one that remains outside the borehole. They are mainly used for small diameter drilling, for example for mineral exploration or the installation of tie rods in rock. This system is used for shallow boreholes, as there can be significant deviation due to the structure of the ground drilled through. These drilling rigs can operate in any direction however.

Auger boring: This is a type of rotary drilling using a worm screw (the auger). This type of drilling is mainly used for unconsolidated clay or sand terrain. The excavated material is directly brought to the surface by the worm screw. For deep drilling, it may be necessary to regularly raise the auger to empty it of its excavated material.

Core drilling: Core drilling is similar to rotary drilling, but it uses a crown to extract a sample, called a core, inside the tool.

Percussion drilling: consists in breaking the rock by dropping a tool, the drill bit, by gravity. This type of drilling can only be used vertically. To prevent the borehole from collapsing, it is necessary to case it as it is drilled. The cuttings are reassembled as soon as they interfere with drilling by replacing the drill bit with a flap valve bailer. The flap valve bailer is a type of tube equipped with a tilting flap in the lower part. This tilting flap allows the tube to be filled with excavated material which is then transported to the surface.

Pipe jacking: is mainly used to install horizontal pipes. The tube is pushed progressively by percussion, the excavated material being removed at the end of the drilling operation either by water injection or with an auger. This technique is used in particular to avoid transmitting vibrations to the surrounding buildings or to avoid digging a trench.

Drilling is an important part of mining mines. The equipment used is mainly the top hammer drilling rig or DTH drilling rig. These two are suitable for different mining operations, and the wrong use will cause huge losses. If you want to know the difference between these two rigs, keep reading.

Different Working Principle

Operation Schematic Diagram(a: top hammer drilling rig; b: DTH drilling rig)

Top Hammer Drilling Rig

The impact force of the top hammer drilling generated by the piston of the pump in the hydraulic drilling rig is transmitted to the drill bit through the shank joint and the drill rod, which is the most different from the down-the-hole drill. At the same time, the percussion system drives the drilling system to rotate. When the stress wave reaches the drill bit, the energy is transferred to the rock in the form of penetration by the drill bit. The combination of these functions can drill holes in hard rock.

However, top hammer drilling is usually used for the maximum diameter of 127mm, and the depth of the hole is less than 20M, which has high efficiency.

In Top Hammer Drilling the hammer produces a percussive force on the drill rods or tubes, which is transmitted to the drill bit. The feed device is usually attached with a hinged boom to a mobile unit. The percussive system strikes the drill rod, for example 2,000-5,000 strikes per minute, and the rotation speed can be, for example, 60-200 rounds per minute. Together these elements make it possible to drill holes in the hard rock. The excess material (cuttings) is flushed up from the bottom of the hole by means of pressurized air or water. Top hammer drills are primarily used in mining, construction and quarrying of rock material. Top hammer drilling, combined with the “drill and blast” method, makes the whole excavation process extremely efficient.

DTH Drilling Rig

The down-the-hole drill uses compressed air to drive the hammer behind the drill bit through the drill rod. The piston directly hits the drill bit, and the hammer cylinder provides a straight and stable guide for the drill bit. This keeps the effects of energy from being lost in the joints and allows deeper percussion drilling.

If you want to learn more, please visit our website DTH Drill Bits.

In addition, the impact force acts on the rock at the bottom of the hole, which is more effective and straighter than other drilling operations.

DPH drilling is more suitable for large holes in hard rock drilling, especially for rocks with a hardness of more than 200Mpa. However, for rocks below 200 MPa, not only energy will be wasted, but also the drilling efficiency will be low, which will cause serious wear on the drill bit. This is because when the hammer's piston strikes, the soft rock cannot fully absorb the impact, which severely reduces the efficiency of drilling and slagging.

In DTH drilling, the percussion mechanism – commonly called the hammer – is located directly above the drill bit. The drill pipes transmit the necessary feed force and rotation to the hammer and the bit, along with the fluid (air, water or drilling mud) used to actuate the hammer and flush the cuttings. The drill pipes are added to the drill string successively behind the hammer as the hole gets deeper.

The hammer is fully fluid actuated. It is composed of two mobile parts: a valve, controlling the flow and a piston that strikes on an impact surface directly linked to the bit. The hammer body gives straight and stable guidance of the drill bit.

Differences of Adaption 

JK410 Crawler Mounted Pneumatic Tophammer Drill Rig

Top Hammer Drilling Rig

ㆍThe most suitable for hole diameter between 25–127 mm.

ㆍGenerally, the hole depth is less than 25 meters.

ㆍAdapt to a stable and uniform hard rock.

ㆍThe slag flushing medium is compressed air or water.

ㆍHigh efficiency in shallow holes drilling, the deeper the lower efficiency.

JK650 All In One DTH Drilling Rig

Down the Hole (DTH) Drilling Rig

ㆍThe 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.

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

ㆍAdapt to hard rock and rock formation conditions (compared to top hammer).

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

ㆍHighly efficient in hard rock drilling.

In summary, each drilling rig has its own advantages. When choosing the equipment, you can first look at the actual situation of your project, and decide which type of rig to choose according to the rock formations, geological formations, and working environment of the construction site.

JK Drilling is a large enterprise specialized in the development and manufacture of all kinds of DTH Drilling Equipment. The major products include All-In-One type and separate type DTH rock drilling rigs, DTH well-drilling rigs, and construction drilling rigs.