The down the hole drilling machine (with the hammer directly at the hole bottom) uses high-frequency percussion to break rock, combined with rotary cutting and high-pressure slag discharge, achieving high efficiency and great depth in hard rock drilling. Compared with traditional top-hammer drills, its drilling speed in f=6-20 hard rock can increase by 30-50%, and the hole wall is straighter with less deviation. YG offers two main models, YG412 and YG420, covering compact and power-oriented working conditions.
YG Down the Hole Drill Rig Parameters
| Model | YG412 | YG420 |
| Drilling diameter(mm) | 50~203 | 50~150 |
| Rock hardness | f=6~20 | f=6~20 |
| Drilling depth (m) | 30 | 40 |
| Walking speed(km/h) | 2.5 | 2.5 |
| Gradeability | 30° | 30° |
| Power type | Diesel | Diesel |
| Fuel tank volume(L) | 85 | 85 |
| Hydraulic oil tank volume(L) | 188 | 188 |
| Weight(Kg) | 6300 | 6300 |
| Dimension(mm) | 6600*2110*2500 | 6600*2110*2500 |
How does the Down the Hole Drilling Machine Work?
Many customers are curious about how the down the hole drill rig works. Simply put, its core idea is “the hammer goes down to the bottom with the bit”:
- The hammer goes down to the hole bottom: unlike top-hammer drills that transmit impact energy from the surface, the dth drilling rig’s impactor (DTH Hammer) is installed directly above the drill bit and follows the drill pipe deep into the hole.
- High-frequency pneumatic hammering: compressed air drives the piston inside the impactor to move back and forth at high speed, striking the bit hundreds of times per minute to break hard rock.
- Simultaneous rotary cutting: the drill pipe rotates slowly while impacting, so the bit cuts the bottom surface evenly, keeping the hole round and smooth.
- High-pressure slag discharge: the crushed rock chips are blown out through the annular space between the drill pipe and the hole wall by high-pressure air, keeping the bottom clean and avoiding re-crushing.
- Crawler self-propelled: the whole machine is mounted on a crawler chassis, so it can move by itself, level automatically, and add/remove drill pipes automatically, greatly improving site transfer and continuous operation efficiency.
Introduction to the Core Components of the Down the Hole Drilling Machine
The performance of a dth drilling rig depends on the cooperation of several key components:
- DTH impactor (down the hole hammer): the core working part that converts compressed air into high-frequency impact force. The YG412 is equipped with a 120kg-class impactor, and the YG420 with a 200kg high-torque impactor – impact force directly determines the drilling speed in hard rock.
- Drill bit: mounted at the front of the impactor, it directly cuts the rock. Common carbide-tipped bits cover diameters from 50- 203 mm, with different tooth shapes and numbers chosen according to rock hardness.
- Air compressor system: supplies the compressed air needed for the impactor. Split-type models use a separate wheel-mounted compressor; integrated models have the compressor built into the carrier – each has its own advantages.
- Crawler chassis: gives the machine self-propelled and climbing ability, stable on slopes up to 30°, suitable for mines, slopes, and other rough terrain.
- Hydraulic system: controls the boom lifting, drill pipe rotation, and travel drive. The 188L large hydraulic tank ensures stable operation under prolonged heavy loads.
- Drill pipe: the force-transmitting member connecting the surface power to the bottom impactor, made of high-strength alloy steel to withstand combined impact, torque, and tension loads.
5 Major Advantages of the YG Down the Hole Drilling Machine
- Compact design fits tight spaces: the YG412 is only 2.1m wide, allowing it to enter narrow work sites such as urban subway construction and building foundation support where larger equipment cannot go.
- Outstanding fuel economy: both models come standard with an intelligent fuel consumption monitoring system, reducing fuel use by about 15% compared to similar products – saving a lot over long-term use.
- Two models cover all conditions: the YG412 suits small-to-medium projects and space-limited sites (30m drilling depth, 50- 203 mm diameter); the YG420 suits large mines and hydropower foundation drilling (40m depth, 50- 150 mm diameter).
- Efficient hard-rock drilling: suitable for f=6-20 rocks, including limestone, granite, and quartz sandstone, maintaining stable drilling efficiency.
- Integrated or split optional: the integrated dth boring machine has its own air compressor for easy relocation; the split type uses a separate compressor, suitable for long-term fixed mining operations.
Frequently Asked Questions About the DTH Drilling Rig
Q1: What is the difference between a dth boring machine and a top-hammer drill?
A dth boring machine puts the impactor directly at the hole bottom to hammer the rock, with little energy loss – suitable for hard rock and deep holes (30- 40 m). A top-hammer drill transmits impact energy from the surface, and efficiency drops noticeably with depth – better for medium-soft rock and shallow holes.
Q2: How to choose between integrated and split down the hole drilling machine?
The integrated type has its own compressor and high integration – good for projects that need frequent moves (e.g., hydropower infrastructure, road construction). The split type uses a separate, more powerful and stable compressor – better for fixed mines with long continuous operation.
Q3: How to choose between YG412 and YG420?
If your working space is limited (e.g., foundation support, urban subway) and drilling depth is within 30m, choose YG412. For large mines or hydropower projects needing 40m depth and higher efficiency, choose YG420.
Q4: How hard rock can a dth boring machine drill?
Both YG models handle f=6-20 rocks, covering limestone (f=6-8), granite (f=12-16), quartzite (f=16-20), and other common types.
Q5: What is the fuel consumption like?
The YG412/YG420 have an intelligent fuel monitoring system; the 85L tank supports a full shift, and overall fuel consumption is about 15% lower than similar models.
Contact YG
Whether you are in mining, infrastructure drilling, or blasting construction, YG provides you with professional down the hole drilling machine solutions. The compact YG412 suits tight spaces, and the powerful YG420 meets large-project needs. Contact us for detailed specifications, on-site construction plans, and equipment quotes.
