The quality of a measurement with strain gauges depends essentially on the type of installation and design of the measuring point. A thorough preparation of the installation surface, correct connection, and protective covering are important factors for problem-free results.
Immediately after complete installation of the SG, the measuring point on the surface of the component must be carefully protected from environmental influences by a covering material.
When selecting the covering material, important considerations should be taken:
The measuring point must be in flawless condition before a sufficiently large cover is spread on it, meaning it is free of dirt, moisture, perspiration from hands, and solder residue. All cable entries must also be very carefully sealed off. In addition, only covering materials recommended by SG manufacturers may be used to protect the SG and adhesive layer.
Commonly used covering materials include:
Polyurethane lacquer (PU140) is ideally suited for several purposes, including as a primer layer for a multi-coat covering.
Absolute protection for an unlimited period of time is only possible with a hermetically sealed metallic enclosure. This type of protection can be implemented for standard commercial transducers. However, hermetically enclosing strain gages for experimental purposes can only be implemented with extremely high overhead or not at all.