DHD350 5inch high air pressure DTH down the hole hammer without foot valve

Adriller DHD 350 is a kind of high air pressure DTH hammer without foot valve, and it is our newest design.

It is also one of the most advanced DTH hammers in the world.

 DTH hammer without  value  advantages:
     1. Out of the trouble of foot valve fracture expansion and contraction.
     2. Lower energy consumption and higher impact frequency.The drilling speed is 15%-30% higher than the one with foot valve.
     3. Simple structure,reliable parts,long life span,easy and cheap maintenance.
     4. Lower air and oil consumption.The oil consumption is about 10% lower than the one with foot valve. 

Carbide Selection

Carbide Designs

Perhaps the most fundamental decision when selecting different carbide

 configurations is profile shape. Button bits most commonly have either a hemispherical

or semi-ballistic carbide design; however it is not uncommon to use other carbide designs as well.

Faster

Shorter lifetime and susceptible to breaks : Conical  Full Ballistic

Penetration rate:

Tungsten carbide life time. Semi Ballistic

Slower

Longer lifetime and less susceptible to breaks: Crown Point and Hemispherical

Penetration Rate Vs.Carbide/Bit Life

More, smaller diameter carbide Results in faster penetration Rates, but shorter carbide and Bit life.

Fewer, larger diameter carbide results In slower penetration rates, but longer Carbide and bit life.

bit and rod  vibration  increases when fewer and larger carbide buttons are selected.

Head Profile Design

Flat Face

Applications : Hard and abrasive formations, all round

Typical formations:  Granite, hard limestone, basalt

Convex

Applications:  Soft to medium hard rock, high penetration rate.

Typical formations : Limestone, hard limestone, shale, granite, basalt

Concave

Applications: Medium hard to hard formations, less abrasive, fractured formations, excellent control over hole deviation

Typical formations : Granite, basalt

Concave Kupa

Applications : Special design with ballistic front buttons, medium hard to hard formations, fractured formations.

Typical formations :Granite, basalt