1. Preparation
The following items are needed for gluing and connecting the lead wires:
- Strain gauges & glue
- Connection terminals
- Test piece
- Solvent
- Cleaning cloth for industrial use
- Soldering iron & solder
- Sandpaper (grit 120 -320)
- Marking pen & scale
- Tweezers & pliers
- Extension wire
2. Surface preparation
Before gluing, remove all grease, rust, paint, etc. from the gluing area to obtain a shiny metallic surface. Sand an area slightly larger than the bonding surface evenly and finely with sandpaper.
Use sandpaper with grit 120 to 180 for steel or 240 to 320 for aluminium.
3. Fine cleaning
Clean the sanded surface with an industrial cloth or rag soaked in a small amount of a chemical solvent such as acetone. Repeat the cleaning until no contamination from the surface is visible on the cloth.
After cleaning, attach the meter before covering the surface with an oxidising membrane or re-contaminating it.
4. Applying adhesive
Put an appropriate amount of glue on the back of the strain gage. Normally one drop of adhesive is sufficient, but the number of drops can be increased depending on the size of the strain gage stiffener. Use the glue nozzle to spread the glue thinly and evenly on the back.
5. Curing and pressing
Place the strain gauge in the correct position, place a polyethylene sheet on top and press the strain gauge firmly and evenly with your thumb or a clamp. This should be done quickly as the curing is completed very quickly. The curing time varies depending on the measuring device, test specimen, temperature, humidity and compressive force (approx. 20-60 sec under normal conditions).
6. Raising gauge leads
After the glue has cured perfectly under the polyethylene film, lift the lead wires. Lift the wires a little way up to inside the strain gauge strip while pressing the ends down with tweezers so as not to damage the wires.
7. Bonding connection terminals
Attach the connection terminal near the strain gauge base.
8. Soldering in the lead wires
Place the measuring leads on the meter terminal with some slack and apply the solder so that the metal foil of the terminal is covered with the solder. Excess lead wire should be twisted off with tweezers.
9. Soldering the connecting wires
It is recommended to coat the exposed cores of the connection wires with solder beforehand. Solder the end of the lead wires to the terminals. Be careful not to heat the terminal too much to peel off the metal foil.