Avoid assembly errors
Heavy-duty anchor Guidebook – Part 7
As an amendment to the list of the different types of assembly, the focus here is on processing faults and we will talk in particular on avoiding these processing faults during assembly.
Only the correct assembly guarantees the full performance of the anchors and is therefore of particular importance. Another note: At EJOT you will find the necessary mounting instructions on the packaging of the products. Additional information and data can also be found in a designated assessment document.
We would like to focus on the following basic rules:
Only the correct assembly guarantees the full performance of the anchors and is therefore of particular importance. Another note: At EJOT you will find the necessary mounting instructions on the packaging of the products. Additional information and data can also be found in a designated assessment document.
We would like to focus on the following basic rules:
Fastenings near the edge
In the case of expansion anchors, which are fixed to the surface by frictional connection, larger minimum centre and edge distances must be observed. Here, the greater the expansion, the greater the distance. In the present example of a metal railing, the attachment points were positioned at the top edge of the step. If the minimum distances are too small, the concrete does not have enough mass to absorb the expansion pressure. As a result, the substrate material may flake off and ultimately the attachment point may fail.
Drill
The perfect condition of the drills is also particularly important. High drill bit wear reduces the diameter of the borehole. This enormously complicates the driving in of the anchors and can lead to the breakage of the anchors for example when concrete screws of smaller diameter are used.
Cleaning drill holes
In the worst case, if drilling dust remains in the borehole, the anchor cannot be driven deep enough, which reduces the effective embedment depth and thus the tensile strength. Thorough cleaning of the borehole is therefore essential.
Torque controlled anchors
Many of our expansion and undercut anchors are torque controlled anchors. The correct expansion or undercut in the borehole is only guaranteed if the prescribed torque has been applied using a calibrated torque wrench. Without the use of a torque wrench, there is a risk that anchors with a smaller diameter are tightened excessively, and large anchors are not tightened sufficiently. Too little or too much effort can lead to failure of the attachment point.