Proper installation of strain gauges is critical to ensuring accurate test results. When these gauges are not bonded correctly, the integrity of the data collected can be severely compromised. Selecting the right adhesive tailored to the specific application is also vital for achieving reliable results. In this blog, we will explore the typical installation process using the fast-curing adhesive CN and discuss best practices for bonding strain gauges effectively.
1. Preparation
The following items are required for bonding and leadwire connection: Strain gauges, bonding adhesive, connecting terminals, test specimen, solvent, cleaning tissue for industrial use, soldering iron, solder, abrasive paper (120 ‐320 grit), marking pencil, scale, tweezers, extension leadwire, polyethene sheet, and nippers.
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2. Positioning
Roughly determine a location on the test specimen where the strain gauge is to be bonded.
3. Surface preparation
Before bonding, remove all grease, rust, paint, etc., from the bonding area to provide a shiny metallic surface. Use abrasive paper to abrade an area somewhat larger than the bonding area uniformly and finely with abrasive paper. Finish the surface with #120 to 180 abrasive paper for steel, or #240 to 320 for aluminium.
4. Fine cleaning
Clean the abraded surface with industrial tissue or cloth soaked in a small quantity of chemical solvent such as acetone. Continue cleaning until a new tissue or cloth comes away completely free of contamination. Following the surface preparation, be sure to attach the gauge before the surface becomes covered with an oxidising membrane or becomes newly contaminated.
5. Applying bonding adhesive
Drop a proper amount of adhesive onto the back of the gauge base. Usually, one drop of adhesive will suffice, but you may increase the number of drops according to the size of the gauge. Use the adhesive nozzle to spread the adhesive over the back surface thinly and uniformly.
6. Curing and pressing
Place the gauge on the position, place a polyethene sheet onto it and press down on the gauge constantly using your thumb or a gauge clamp. This should be done quickly as the curing process is completed very fast. The curing time varies depending on the gauge, test specimen, temperature, humidity and pressing force. The curing time under normal conditions is 20-60 seconds.
7. Raising gauge leads
After the adhesive beneath the polyethene sheet has been perfectly cured, raise the gauge leads. Raise the leads up to a bit inside the gauge base while pressing down the foot of the leads with tweezers, not to damage the leads.
8. Bonding Connecting Terminals
Bond the terminal close to the gauge base. Foil-type connecting terminals.
9. Soldering the gauge leads
Place the gauge leads on the gauge terminal with a little slack and apply solder so that the metal foil of the terminal is covered with the solder. An excess gauge lead should be twisted off by tweezers.
10. Soldering Leadwires
It is recommended to plate the exposed core wires of the extension leadwires with solder preliminarily. Solder the end of leadwire to the terminals. Take care not to excessively heat the terminal to peel off the metal foil.
We hope this article has helped you understand the basics of installing a strain gauge. If you need assistance, please feel free to reach out to us. We offer sensor installation services through our sister company, Quad I. If you require a sensor installation service, do not hesitate to contact us at +44 (0) 3300 101498 or send an email to hello@wearequadi.com. Check out the Quad I website by clicking here!
