Small Boring Unit
Definition - What does Small Boring Unit mean?
A small boring unit is a cutting assembly attached to an auger boring machine. It was developed to enable contractors to bore through very hard rock which would otherwise be slow or impossible with older generation cutting assemblies. The disk cutter design is more effective than roller cone cutters for rock as hard as 38000 psi unconfined compressive strength (UCS). These assemblies are an essential element of trenchless construction.
Trenchlesspedia explains Small Boring Unit
Small boring units are mounted on a bearing and have much lower vibration levels than roller cone cutters. This makes them suitable for use in hard rock, around other utilities and also near residential areas. An added advantage is that the unit works with pressure rather than percussion or force. The disk cutter head design is very effective at penetrating hard rock. Different materials can be used for the perimeter cutters and those at the center. Small boring units are mounted to a lead casing and are typically driven by an auger boring machine (ABM).