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Frequently Asked Questions

Here are some answers to our Frequently asked Questions, and our Acronyms explained We update this page regularly.



(TH) Top Hammer Drilling, the hammer produces a percussive force on the drill rods or tubes, which is then transmitted to the drill bit.

The feed device is usually attached with a hinged boom to a mobile unit. The percussive system strikes the drill rod, for example 2,000-5,000 strikes per minute, and the rotation speed can be, for example, 60-200 rounds per minute.

Together these elements make it possible to drill holes in the hard rock. The excess material (cuttings) is flushed up from the bottom of the hole by means of pressurized air or water. Top hammer drills are primarily used in mining, construction and quarrying of rock material. Top hammer drilling, combined with the “drill and blast” method, makes the whole excavation process extremely efficient.

Just Drill are suppliers for Robit products exclusively in the UK and Ireland


A down-the-hole drill, usually called DTH is mainly a pneumatic powered rock or ground drill, in which the percussive hammer is located directly behind the drill bit, so the percussion mechanism follows the bit down into the drill hole. The drill pipes transmit the necessary feed force and rotation to the DTH hammer and bit, as well as compressed air for the DTH hammer. Air flushes cuttings up from the bottom of the hole. Drill pipes are added to the top of the drill string as the hole gets deeper. The piston directly strikes the impact surface of the bit, while the hammer casing gives guidance to the drill bit. The fast hammer impact breaks hard rock into small particles, which are blown up by the air exhaust from the DTH hammer.

Just Drill supply Robit products in the UK and Ireland


Robit’s Reverse Circulation (RC) products help you drill deeper and faster and importantly delivering high quality samples for your customer. Reverse circulation is achieved by blowing air down the rods, the differential pressure creating air lift of the water and cuttings up the “inner tube”, which is inside each rod. It reaches the “divertor” at the top of the hole, then moves through a sample hose which is attached to the top of the “cyclone”. The drill cuttings travel around the inside of the cyclone until they fall through an opening at the bottom and are collected in a sample bag.

Rotary Drilling

Rotary drilling is a method of drilling that employs a sharp, rotational drill bit to bite its way through the earth’s crust. It relies upon high rotational speeds and thrust without percussion to achieve the desired effect and outputs. In rotary drilling, the rock is made to fracture by means of a combination of “pull down” pressure on the bit and rotational power “torque”. Weight is applied to gouge, chip and grind the rock. Tricone rotary bits are sometimes a good alternative to a DTH hammer. It is used in the construction, mining, and oil industries as well as water & thermal wells. Robit offers TCI (carbide buttons) and mill tooth configurations, again only available through Just Drill in the UK and Ireland.

Robit Casing Systems

Robit® Casing Systems are the key components of the ground drilling applications and exclusively available through Just Drill in the UK and Ireland. Their patented locking system enables easy and reliable drilling cost effectively. Robit® Casing Systems have several references worldwide in all major ground drilling applications:

For Example:

  • Site investigation: Casing tube is driven to selected depth, the hammer and pilot are withdrawn to allow the Core barrel to take the sample below.

  • Horizontal drilling: Casing is drilled in horizontally and then after the pilot and hammer are removed cables, pipes can be inserted avoiding the surface or road being disturbed.

  • Anchoring: This system is used to drill through overburden to depth and then with the Non Stop system you can continue drilling forward at the same diameter in the rock.

  • Water and thermal drilling: This system is used to drill through broken ground and overburden, after achieving the depth the casing is left in the hole as part of the installation.

  • Piling, micro piling and underpinning: Used to assist in the installation of Drilled Concrete piles to support new buildings in soft ground. This system provides fast drilling, maximum hole straightness and reliability to achieve the targeted depth.

Why use Perforator?

PERFORATOR GmbH is a leading German drilling equipment manufacturer with more than 30 years of experience and have been supplying a wide range of Horizontal and Vertical Drilling Technologies over those 30 years. The company's core competence lies in Auger Boring Technology, Drill Pipes and Accessories, Disc Cutters and Injection Technology.

Perforator’s quality management system is DIN EN ISO 9001:2018 approved and the drill pipe production is certified acc. API Spec 5DP – license 5DP-0071 and API Spec 7-1 – license 7-1-0051.

The main product range include: Performance Pipes: Pipes and Tools for DTH, Rotary, Reverse Circulation Drilling and more Performance Drilling: Thrust Boring Machines and Tools Performance Pumps: Injection systems Performance Cutters: Cutters for Tunnel Boring equipment

Just Drill are the exclusive supplier and stockist of Perforator Drill Pipe in the UK and Ireland.

Auger Boring

Auger boring is beneficial where, for example road rail or other crossings are required and trenched options would be highly disruptive and cause inconvenience to road and rail users, local population and businesses. Auger boring is a non-displacement technique which enables installation without ground heave. 

Perforator's Auger Drilling Rigs, Pipe Bursting Rigs and Vertical Earth Drills are used every day all over the world and ensure precise work with maximum efficiency.

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