Mikroschlag: eine Revolution im trockenen Diamantbohren

Drilling holes is one of the most common operations in construction, renovation, and installation of engineering systems. Without it, it is impossible to install sockets, lay communications, mount air conditioners, ventilation, or heating systems. The precision and speed of drilling largely determine the quality and timelines of the entire project.
For a long time, craftsmen used three main types of equipment for these tasks:

• Rotary hammers and impact drills — for creating holes of small diameter and depth, most often when installing dowels, anchors, or back-boxes;

• Diamond drilling rigs with water cooling — for deep or large diameter holes when high precision and minimal vibration are required;

• Today the market is actively developing, and more and more dry diamond drilling machines are appearing, allowing holes to be made without water supply, while preserving high speed, neatness, and cleanliness of work. These machines have become a true breakthrough for those who work in premises with finished refurbishment or in conditions where the use of cooling fluid is undesirable.
  Machines that are equipped with innovative micro-impact technology deserve special attention. Thanks to it, the tool copes even with reinforced and high-strength concrete, where a standard rotary hammer or drill often proves powerless. This makes such drilling one of the most promising directions in modern construction and installation.
  For effective work in this mode, special diamond core bits are used, designed specifically for micro-impact influence. Their construction and segment shape allow the load to be distributed uniformly, reducing the risk of accelerated wear, thus ensuring a long service life and stable drilling quality.

Principle of micro-impact
On standard core drills, manufacturers often indicate a warning: “Do not use in hammer/impact mode.” This is because a standard rotary hammer or impact drill’s impact mechanism creates strong, short, rigid impulses. Such an impulse passes excessive load onto the drill body, causes deformation and welding or brazing failure of the diamond segments, especially when working at high speeds. In addition, under heavy vibrations the centering of the drill is compromised, leading to run-out, overheating, and accelerated tool wear.
Micro-impact technology is based on a different principle. The drill’s design includes a mechanical unit of two ratchets that engage with each other at each shaft revolution. In the moment of their engagement a small, gentle jolt is created – sufficient to break the micro-layer of concrete at the contact zone of the segments with the material, but not so strong as to damage the core bit itself.
Such micro-impacts occur at a very high frequency — up to 50 000 per minute — which makes the drilling process smoother and reduces the load on the tool. Essentially, the drill does not “hammer” the material like a rotary hammer, but vibrationally splits the concrete, facilitating the core bit’s passage and lowering the temperature on the cutting edge. This is especially important in dry drilling, where there is no cooling fluid.
As a result, micro-impact:

• increases drilling speed without losing precision;

• reduces load on the diamond segments;

• prevents jamming of the core bit in the material;

• reduces vibration transferred to the operator’s hands.
  Thanks to this principle of operation of micro-impact drills, one can safely use diamond core bits specially designed for this mode — they have a reinforced body, stable segment brazing, and optimized edge geometry for micro-vibration work.

What to pay attention to when choosing a micro-impact drill

• Motor power — from 1.5 to 3 kW. Higher power provides performance margin and stable operation at large drilling diameters.

• Rotational speed — no less than 1500 rpm. The higher the rpm, the higher the frequency of impacts and the faster the drilling.

• Speed selection — availability of two or three speeds allows optimizing rpm under the bit diameter.

• Maximum bit diameter — depends on the tool’s power. The higher the power, the larger the allowable diameter.

• Spindle mount — most often 1 ¼ UNC or M16–M18. Choose bits or adapters for the specific standard.

• Dust extraction — in dry drilling much dust is generated, so it is important to have built-in dust removal or use attachments, e.g., Drillstream™ by Mechanic.

• Use of a stand — when drilling hard materials or large diameters, a stand provides stability and reduces operator load.
  Research has shown that the amplitude of the impact in different models ranges from 0.3 to 0.9 mm. The higher it is, the faster the segments wear and the stronger the vibration causing operator fatigue.

Advantages of dry drilling
The main benefit of the technology is the possibility of drilling without water and contamination. In dry drilling there is no sludge and dirty flows typical of systems with water cooling, and all generated dust is effectively removed by an industrial vacuum. This is especially convenient when working in premises with finished renovation, in residential or office buildings, where moisture on finishes, furniture or electrical equipment is unacceptable.
Another important advantage is the significant increase in drilling speed. Compared with a standard rotary hammer, a micro-impact drill makes a hole for a socket in solid concrete 4–5 times faster:

• rotary hammer — 4–5 minutes;

• micro-impact drill — less than 1 minute.
  Such acceleration is achieved because of high impact frequency (up to 50 000 per minute) and optimal interaction of diamond segments with the material surface. Time savings become especially noticeable for large volumes — for example, when drilling 50–100 or more holes in a row.
  Micro-impact drills are also successfully used for drilling reinforced concrete (which is especially difficult for a rotary hammer or ordinary drill); however when passing through rebar it is recommended to switch off the micro-impact mode to avoid blunt segments and extend bit life.
  Thus, dry drilling with micro-impact combines cleanliness, speed, precision and versatility, making it the optimal solution for most installation and finishing tasks.

Scope of application
The technology of dry drilling with micro-impact is universal and suitable for a wide variety of tasks in construction, renovation and installation of engineering systems. It allows to quickly and neatly create holes in materials of different strengths, minimizing dust and vibration, which is especially important when working in premises with finished refurbishment.
Main application areas include:

• drilling holes for sockets, switches and mounting boxes;

• mounting air conditioners, exhausts, recuperators and ventilation channels;

• installing heating systems, water supply, sewage and ventilation;

• carrying out demolition works and breaking holes in walls and partitions;

• creating holes for wiring, cable ducts and communications;

• preparing openings for pipes, chimneys and risers of engineering systems;

• drilling in reinforced concrete, concrete blocks and foundation structures;

• working with bricks, light concrete (M150–M200), foam-concrete blocks and abrasive materials;

• installing interior elements, e.g., decorative constructions or niches for built-in appliances.
  Thanks to high precision and controlled micro-impact action, the technique is also excellently suited for complex architectural and restoration works, where it is important to preserve surface integrity and minimize material damage.

Conclusions
The technology of dry drilling with micro-impact is confidently gaining popularity thanks to the combination of speed, cleanliness and versatility. It allows performing holes of large diameters and depths without cooling fluid and with minimal dust. For correct work it is necessary to use special core bits designed for micro-impact mode. Use of ordinary bits will lead to their accelerated wear and increased unit cost of a hole.