Down The Hole Hammer

Down-the-Hole (DTH) Hammer – Overview & Working Principle

A Down the Hole hammer is a high-performance drilling tool used in mining, quarrying, water well drilling, and construction. It operates at the bottom of the borehole, delivering powerful percussive blows directly to the drill bit for efficient rock penetration.

Pulanka Series:

How a DTH Hammer Works

1. Pneumatic/Hydraulic Power

- Compressed air (or hydraulic fluid) drives a piston inside the hammer.

- The piston strikes the drill bit at high frequency (up to 2,000 blows per minute).

2. Impact & Rotation

- The hammer's energy is transferred directly to the bit, crushing the rock.

- The drill string rotates slowly, ensuring even wear and hole straightness.

3. Flushing (Cuttings Removal)

- Air (or fluid) exits through the hammer, flushing rock cuttings up the hole.

Key Components of a DTH Hammer

Part Function

Piston Strikes the drill bit with high impact energy.

Backhead Connects to the drill string and directs airflow.

Bit Carbide-button or insert bit that crushes rock.

Front Head Guides the bit and maintains alignment.

Air Distribution System Controls airflow for piston movement and flushing.

Types of DTH Hammers

- Standard DTH Hammers – Most common, used in mining and water wells.

- High-Pressure DTH Hammers – For deeper holes (requires higher air pressure).

- Low-Pressure DTH Hammers – Used in shallow drilling with limited compressor capacity.

- Water-Flushed DTH Hammers – For environments where air flushing is impractical.

Advantages of DTH Hammers

✔ Higher Penetration Rates – More efficient than top hammer drilling in hard rock.

✔ Better Hole Straightness – Ideal for deep, vertical holes.

✔ Reduced Energy Loss – Impact occurs at the bit, not through the drill string.

✔ Versatility – Works in granite, basalt, limestone, and other hard formations.

Applications

- Mining & Quarrying (Blast hole drilling)

- Water Well Drilling

- Geothermal Drilling

- Construction & Piling

- Oil & Gas (Shallow Wells)