General Introduction:

PLATO DTH hammers are all simple structure, easy to assemble and disassemble, as well as reliable quality and long service life. Acedrills has various hammer models suitable to drill holes from 64mm to 1000 mm (2-1/2” ~ 39-3/8”) in diameter; and come with three kind: low pressure (5 ~ 7 bars), middle pressure (7 ~ 15 bar) and high pressure ­­(7~ 30 bars).

PLATO DTH hammers mainly be produced with shank type of DHD, QL, SF, COP, Mission, SD, BR, CIR and ACD series, Diameter ranging from 2” to 8” for mining and quarrying, and 6” to 32” for water-well drilling, oil-well drilling and foundation and so on;

DTH Hammer Selection:

Choosing the right hammer is largely determined by drill machines (mainly compressor output), drilling hole size and type of rock formation. Ideally, the size of the hammer should match the required hole dimension as closely as possible, leaving just enough space for compressed air to flush cuttings and clean the hole.

The optimum range of hole size for blast-hole drilling with DTH method is 90~254 mm (3-1/2” ~ 10”) with 3.5 ~ 8” hammers. Smaller blast holes are generally drilled with top-hammer tools, while larger holes typically with rotary drilling tools. In other applications, like foundation drilling, DTH hammers can be used in hole size up to 1,000 mm (39-3/8”).

Usually, the smallest hole diameter a DTH hammer can drill is its nominal size, for example, a 4” hammer would drill a 4” (100/102 mm) hole. The limiting factor is the outside diameter of the hammer, because, as hole diameter reduces, airflow is restricted. Maximum hole size for production drilling is the nominal hammer size plus 1”for 5” and smaller hammers and plus 2 for 6” and bigger hammers, for example, for a 4” hammer the maximum hole size is 5” (127/130mm) while for a 8” hammer the maximum hole size is 10” (254mm).

Specification Overview:

High Pressure DTH Hammers:  

Middle Pressure DTH Hammers:

Low Pressure DTH Hammers:

Big Size DTH Hammer for Water Well Drilling and Foundation Drilling:

How to order?

Shank Type + Top Sub Thread + (With/Without Valve, if this parameter is optional)

PLATO DTH DRILLING TOOLS CHAIN

PLATO is in the position to supply clients full range parts for DTH drilling tools chain, including DTH hammers, bits (or bits equivalent function tools), sub adapters, drill pipes (rods, tubes), RC hammers and bits, dual-wall drill pipes and hammer breakout benches and so on. Our DTH Drilling tools are also well designed and manufactured for mining, water well drilling industries, exploration, construction and civil engineering.

The down-the-hole (DTH) method was originally developed to drill large-diameter holes downwards in surface-drilling applications, and its name originated from the fact that the percussion mechanism (the DTH hammer) follows the bit immediately down into the hole, rather than remaining on with the feed as the ordinary drifters and jackhammers.

In the DTH drilling system, the hammer and bit are the basic operation and components, and the hammer is located directly behind the drill bit and operates down the hole. The piston strikes directly the impact surface of the bit, while the hammer casing gives straight and stable guidance of the drill bit. This means no impact energy loose through any joints at all in the drill string. The impact energy and penetration rate therefore remains constant, regardless of the depth of the hole. The drill piston is powered by compressed air delivered through the rods at supply pressure ranging typically from 5-25 bar (0.5-2.5 MPa / 70-360 PSI). A simple pneumatic or hydraulic motor mounted on the surface rig produces rotation, and flushing cuttings is achieved by the exhaust air from the hammer either by compressed air with water-mist injection or by standard mine air with a dust collector.

The drill pipes transmit the necessary feed force and rotation torque to the impact mechanism (the hammer) and bit, as well as convey compressed air for the hammer and flush cuttings by that the exhaust air blows the hole and cleans it and carries the cuttings up the hole. The drill pipes are added to the drill string successively behind the hammer as the hole gets deeper.

DTH drilling is very simple method for the operators for deep and straight hole drilling. In the hole range 100-254 mm (4” ~ 10”), DTH drilling is the dominant drilling method today (especially when the hole depth is greater than 20 meters).

The DTH drilling method is growing in popularity, with increases in all application segments, including blast-hole, water well, foundation, oil & gas, cooling systems and drilling for heat exchange pumps. And applications were later found for the underground, where the direction of drilling is generally upwards instead of downwards.

The main features and advantages of DTH drilling (mainly compare to top-hammer drilling):

1.Wide range of holes sizes, including extremely larger hole diameter;

2.Excellent hole straightness within 1.5% deviation without guiding equipment, more accurate than top-hammer, due to the impact being in the hole;

3.Good hole cleaning, with plenty of air for the hole cleaning from the hammer;

4.Good hole quality, with smooth and even hole walls for easy charging of explosives;

5.Simplicity of operation and maintenance;

6.Efficient energy transmission and deep hole drilling capacity, with constant penetration and no energy losses in joints through the drill string from start to finish of the hole, as with top hammer;

7.Creates less debris hang-up, less secondary breaking, fewer ore pass and chute hang-ups;

8.Lower cost on drill rod consumables, due to drill string is not subjected to heavy percussive force as with top hammer drilling and drill string life is therefore greatly lengthened;

9.Reduced risk of getting stuck in fractured and faulted rock conditions;

10.Lower noise level at the worksite, due to the hammer working down the hole;

11.Penetration rates are almost directly proportional to air pressure, therefore doubling the air pressure will result in approximately double the penetration.