LIEBIG ULTRAPLUS® Undercut Anchors
Undercut anchors are specially designed for use in concrete. While choosing the anchors, some important factors should be considered, including the concrete strength and condition (cracked or non-cracked), anchor spacing, distance between edges, structural thickness, value and angle of the applied load, thickness of the fixture, the environmental conditions as an absolute minimum.
Operating Principle and Performance
An undercut anchor works by creating a positive mechanical interlock within a concrete structure. This positive mechanical interlock is what gives this type of anchor a performance way above that of normal mechanical expansion anchors.
In the case of the Liebig Ultraplus, a special undercutting tool is used to create a uniformed void around the lower section of the drilled hole, Once the anchor is inserted, the spring loaded mechanism of the anchor forces out the expansion keys in to the void and the interlock is created. This type of anchor and the interlock it creates offer by far the highest performance and resistance compared to other types of undercut anchor. Anchors are designed such that rather than concrete capacity it is the steel from which the anchor is produced which can be fully utilised to provide the ultimate resistance.
Other types of undercut anchors tend to be installed as follows:-
Self-undercutting-rotary and self-undercutting-percussion. In the pre-drilling technique, a special drill is manipulated eccentrically by hand to create to create the undercut shape,
For the self-undercutting-rotary process, a stop drill is employed to form a cylindrical hole. From there, the anchor is positioned in the bottom of the hole, a special adapter and a hammer drill is used to spin it into the hole; the special teeth of the anchor create the undercut shape as it spins.