Diamond trenching is three times faster than conventional methods using an excavator and shovel. The trench is created and the empty pipe laid in a single operation, and the 30 mm wide slot is filled directly afterwards. This minimally invasive procedure, which is preferably used in cemented ground, saves enormous amounts of time and money and places far less strain on residents than any alternative method. Diamond trenching is the smart new solution in fibre optic expansion and shows its advantages especially in the development of the famous last mile (Fibre to the Home).
A pilot project in Bad Wurzach, Germany – LISSMAC's home town – demonstrates the advantages of diamond triangulation in densely populated areas. Graf Tiefbau – a firm from Leutkirch, Germany – received an order to produce some 40 glass fibre house connections at the Ziegelwiesenweg industrial estate. They commissioned road construction professionals from OAT in Oberpframmern, who used two diamond cutting machines from LISSMAC for the actual trench work and backfilling. Application engineers from LISSMAC supported the project on-site, trained the operating team on the diamond cutting machines and helped to optimise the new work processes.
2 kilometres of cable duct in 15 days
"We don't need to dig deep ditches, we don't close off complete roads, we don't block property access for days on end and we don't leave an unsightly finish on the asphalt surface. Residents can use their driveways again after just one hour, and after a 24 hours almost all traces have been removed," says Franz Bareth, application engineer and diamond cutting specialist at LISSMAC, describing the advantages of the process from a practical point of view. The LISSMAC DT 60 diamond cutting machine works its way through the demanding Bad Wurzach subsoil at about 1 metre per minute, laying up to 12 x 10 mm + 1 x 20 mm conduits in the 38 cm deep cable duct in a single operation. "We would even manage 2 metres a minute if the ground under the asphalt was not so loosely gravelled but more compact," says Bareth. Despite the adverse ground conditions, the installation speed is tremendous. The LISSMAC DT 60 cut the approximately 2 km long cable duct through the "Ziegelwiese" industrial estate in just 15 working days. After 17 days, the project was completed, the house connections were laid, and the trenches cleanly backfilled, compacted and sealed with mastic asphalt. "Diamond trenching is much faster than conventional excavation. The building contractor saves immense personnel costs and can put the working time gained into other projects. The narrow slits can be crossed immediately by cars or trucks – an invaluable advantage of our process, especially in busy commercial and residential areas,” says Roland Gaile, Head of Diamond Trenching at LISSMAC.
Only the toughest are up to the task
Sawing 38 cm deep and 30 mm wide in a single step into asphalt puts a massive strain on the trenching machine. Conventional floor saws – which are designed for step cutting which is gentle on the material – would be overwhelmed by this. Only the two most powerful LISSMAC models are suitable for diamond cutting. The flagship UNICUT 600 floor saw serves as the basis for the DT 60. A diamond trenching attachment kit has been developed for this 136 HP power package. This consists of a special hood that deposits the machined material to the side. Also integrated is the laying unit, which looks like a plough and positions the empty pipes directly following the cutting blade on the bottom of the duct. Attached to the DT 60 is the cable truck, which in its current version can carry up to 16x 1m reels. “Our UNICUT 600 in the diamond trenching version DT 60 is perfect for this highly demanding task. It is hydraulically controlled, which makes the cutting blade drive extremely robust and resistant to heavy-duty loads without significant wear. As a technician, I really enjoy seeing and feeling how powerfully and smoothly the drive with the 100 kW Deutz engine slices through the heavy load when cutting. And I can control all of this with centimetre precision with a touch of the joystick,” says LISSMAC application engineer Bareth.
Diamond trenching - especially fast in a team
The DT 60 is required to cover a distance of at least 1 m/min and to cut the cable duct straight ahead along the specified route. Ideally, the somewhat smaller, manoeuvrable LISSMAC DT 90 should be at your side to quickly create the branch lines to the house connections. For this purpose, the MULTICUT 900 serves as a resilient basic machine whose 55 kW/74.8 HP motor drives an 800 mm cutting blade that produces 30 cm deep and 20 mm wide grooves. The larger DT 60 works with an enormous 1,000 mm trenching blade, a special design for extra deep (38 cm) and wide (30 mm) cuts. The heavy-duty diamond tool for trenching is the result of many years of development work by LISSMAC and its partners, which incorporates decades of experience on the part of the cutting and tool specialists and years of detailed work. "Our diamond cutting machines have been in use for several years already in Scandinavia. We have now also equipped a major fibre optic expansion project in England with our machines and expertise. A lot of practical experience and development work has already gone into the machines and the special diamond tools. In Germany, the most important thing now is to show the responsible planning authorities what our technique can do. The project in Bad Wurzach should contribute to this with a successful outcome,” adds Roland Gaile.