What things do I need to consider when mounting a load cell?

A load cell will only perform to its specification if it is mounted correctly. Many times, the load cell is blamed for poor measurement performance when, in fact, the mounting arrangement is the source of the inaccuracy. In order of for the load cell to perform correctly, the strain-gauged element must be uniformly stressed when under load. In order for this to happen, the following conditions should be met:

• Flat surface - The mounting surface for the load cell should be flat, preferably a ground surface. This ensures that the load cell is strained evenly and that high spots do not induce an uneven loading on the load cell and, therefore, uneven stress levels.

• Hard, rigid surface - The mounting surface for the load cell should be hard and rigid. This ensures that the surface does not distort or bend and twist under loading conditions. The loading stresses on the surface can be very severe, particularly when miniature load cells are being used. Loads of 40,000 lbs per square inch are not uncommon. once again, if the surface is hard and rigid, it will not distort and this ensures that the load cell is strained evenly and, therefore, experiences even stress levels.

• Level surface - The surface should be level so that all the load is applied parallel to the main axis of the load cell. This ensures that no cosine error is induced, but it also ensures that side loading does not create problems for the load cell, which will only have some degree of immunity.

Loading applied parallel to the main axis ensures that the load cell only sees loads that are parallel to the main axis. In tension load cells, rod-end bearings can ensure that the load is always applied parallel to the main axis and in compression, load cell load buttons fulfill a similar function.