Novedades

With ERKAT power and BETEK bite

Low-vibration milling cutters beneath a listed historical building.

The Mönchstein Hotel in Salzberg was to be extended by two new floors. The challenge lay in three factors at the same time. The first being that the Hotel is built into the hillside above the Salzach. In the second place and as the building is subject to strict classification as a listed building the two floors were to be constructed underneath the building. For that reason, and in the third place, the conglomerate rock below the building had to be removed with as little vibration as possible.

In this job the very nature of explosives and hydraulic hammers excluded them from use. The use of compressed air hammers would have been to time-consuming and the deployment of diamond wire saws too costly. The best solution for this difficult site situation was an ERKAT special milling cutter fitted with BETEK tools. This combination was shown to have unique advantages. ERKAT milling cutters are low- vibration in operation whilst at the same time they possess a high rock-breaking capability. BETEK tools rotate in an optimum manner and are able to meet the high requirements demanded. This enables the excellent performance of the special milling cutter to be exploited to the full. Transporting the heavy equipment through the narrow alleyways of the Salzburg old town to the construction site was difficult to organise. First of all the space for the entrance to the planned underground car park was cut out of the rock beneath the building. For this job the ERKAT "ER 1500-3S" special milling cutter was fitted with 48 BETEK round-shaft bits of the type B47GK17.5LK75/70 (BGS 78). This robust bit is characterised by the good quality of the tungsten carbide tips specially tailored to this special application. The bit's wide collar covers a large area of the holder and in this way protects against premature wear.

Low-vibration excavation? The ERKAT special cutter! The medium-hard stone conglomerate was excavated with a cutting force of up to 64,000 Newton. In any case, ERKAT's special cutter can excavate stone with a pressure resistance of up to 120 Mpa. Each day up to 100 m³ of stone was dug away from the cliff face. A total excavation volume of 4,500 m³ was achieved. In doing so the undermining of the existing body of the building made the greatest possible demands on low-vibration working. This was only possible with an extremely sensitive feeling for the work, gained through many years experience of dealing with cutting technology. The rock was hewn away with even, horizontal strokes. As they made these movements, the special mill- cutting machines slowly worked their way down into the hill. It was a job that brought to bear the full expertise of specialist cutting firm 'Niggas Fräsen' from Berlin, a key factor in the project being completed on time.

At the same time, the close collaboration between the machine and tool manufacturers paid off for the end customer. Precisely in the case of special applications the professional matching of machine and tool brings in its wake benefits in terms of costs, time and processing, and is often the only way construction site management can be made economic.

Undermining the existing body of the building placed the highest demands on the Niggas company's milling cutters.

Erkat ER1500-3S milling cutter and BETEK BGS78 round- shaft bit in action.