Selecting the Right Hammer

The optimum range of hole size for blast hole drilling with DTH is 90 mm to 254 mm (3 ½”–10″). Smaller blast holes are generally drilled using tophammer, and larger holes generally use rotary machines.

In other applications, like foundation drilling, DTH hammers can be used with single bit in hole sizes up to . 750 mm (30″). With multiple hammer units CD (Cluster drills) drill holes up to 70″ or 1778 mm.

As a rule of thumb, the smallest hole diameter a DTH hammer can drill is its nominal size. A 4 inch hammer will drill a 4 inch (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 inch, so for a 4 inch hammer the maximum hole size is 5 inch (127–130 mm).

Choosing the right hammer is largely determined by 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 cuttings to evacuate the hole.

Secoroc hammers are purpose-matched for all rock types and applications. Where high performance is the main criterion, Secoroc COP Gold hammers are recommended in blast hole drilling and Secoroc Total Depth hammers in deep hole drilling applications. The Total Depth hammer has proven superior performance and adaptability to different air requirements thanks to the Air Select System.

Where proven technology is required, the Secoroc COP and Quantum Leap hammers are known for their reliability and longevity. For a reliable workhorse, the Secoroc DHD and DHD-QL is practically bullet proof, making them useful for production drilling in quarries, shallow water well drilling, and underground blast hole drilling.

HD is similar to Standard, but with heavy duty chuck and wear sleeve, and a top sub fitted with tungsten carbide buttons for wear protection in harsh and abrasive conditions. These also protect the top sub from excessive wear when rotating out of the hole through broken rock.

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