Introduction to dth hammers

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.

Air Consumption / Operating Pressure

Product codes are a valuable tool to describe and identify the product. In the code structure we have tried to describe the product features with an alphanumeric system and not always 100% logical, but with the attached key you will be able to find the product you are looking for or alternative products.

Air Consumption / Operating Pressure

Specifications

Hammer	BR2A	DHD3.5	HK4D	HD45	HQL4A	HQL50	HK5Q	HD55	HQL60	HQL6A	HQL80	HD85	HK9Q	HSD10	HSD12	HK12Y	N125-R
Recommended bit size, mm	76	92-105	112-127			140-152			165-178		203-229		216-229	245-305	305-445	305-350	305-445
Bit Shank	BR2A	DHD3.5	DHD340A		QL40	QL50		DHD350	QL60		QL80	DHD380	QL80	SD10	SD12	HY12	NUMA125R
External diameter, mm	63	82	100	100	101	126.5	127.5	126.5	148	146	185	185	203	225	275	275	275
Length excl. thread, mm (Less bit)	837	855	915	1032.5	1057	1147	935	1167	1121	1182	1471	1487	1345	1413	1680	1590	1812
Hammer weight, kg (Less bit)	14.1	25	37.5	40.6	41	71.6	67.6	77.2	105	105	203	206	228	303	526	510.2	546
Package case size	(L)910 (W)90 (H)120	(L)1200 (W)110 (H)140	(L)1010 (W)130 (H)160	(L)1080 (W)125 (H)134	(L)1150 (W)130 (H)160	(L)1290 (W)150 (H)175	(L)1100 (W)155 (H)180	(L)1290 (W)150 (H)175	(L)1270 (W)170 (H)200	(L)1260 (W)180 (H)200	(L)1440 (W)230 (H)270	(L)1560 (W)230 (H)270	(L)1500 (W)240 (H)280	(L)1620 (W)275 (H)290	(L)1880 (W)320 (H)320	(L)1665 (W)320 (H)360	(L)1880 (W)310 (H)310
Top Sub thread	RD50	2-3/8″ API REG				3-1/2″ API REG					4-1/2″ API REG			6-5/8″ API REG		6-5/8″ API REG 7-5/8″ API REG	6-5/8″ API REG
Working Pressure, PSI	80-170	150-250	200-300			250-350			300-350		300-380			300-380	150-350	200-350
Air consumption, CFM	250-350	300-400	500-700			500-800			600-900		950-1200			950-1200	1000-1800	1200-1500	800-1800
Piston diameter, mm	42.7	65	82	80	80	104	102	100	122	121	150	150	165	185	225
Piston weight, kg	1.7	5.1	9.2	9	9	17	17	16	24	24	38	42	50	68	110	111	111
Wrench flat, mm	L47 W50	L57 W35	L74.5 W45	L64 W40	NO wrench flat	L89 W60	L88 W50	L89 W60	L101 W65	L101 W60	L128 W70	L140 W70	L128 W70	L140 W70	L140 W70	L140 W70	L140 L70
Feed force, kN	2~6	3~8	5~15			6~25			7~20		10~25			15~30	20~35
Rotation speed, r/min	30-70	3-90	25-80			20-70			25-60		20-60			15-35
Drilling conditions and project specifications may require larger air package to be used