Strain Gage Surface Preparation (Advanced Sensors Technology)

Advanced Sensors Technology Strain gage sensors ( CEA, C4A, C5K etc.) can be satisfactorily bonded to almost any solid material if the material surface is properly prepared.

While a properly prepared surface can be achieved in more than one way, the specific procedures and techniques described here offer a number of advantages. To begin with, they constitute a carefully developed and thoroughly proven system; and, when the instructions are followed precisely (along with those for gage and adhesive handling), the consistent result will be strong stable bonds. The procedures are simple to learn, easy to perform, and readily reproducible. The importance of attention to detail, and precise adherence to instructions, cannot be overstressed in surface preparation for strain gage bonding. Learn more on http://www.micro-measurements.com.

Our 5 steps are:

Degreasing
Abrading
Burnishing of Layout Lines
Conditioning
Neutralizing

Thoroughly degrease the gaging area with solvent, such as CSM Degreaser or GC-6 Isopropyl Alcohol. The former is preferred, but there are some materials (e.g., titanium and many plastics) that react with strong solvents. In these cases, GC-6 Isopropyl Alcohol should be considered. All degreasing should be done with uncontaminated solvents-thus the use of “one-way” containers, such as aerosol cans, is highly advisable.

Preliminary dry abrading with 220- or 320-grit silicon-carbide paper is generally required if there is any surface scale or oxide. Final abrading is done by using 320-grit silicon-carbide paper on surfaces thoroughly wetted with M-Prep Conditioner A; this is followed by wiping dry with a gauze sponge. Repeat this wet abrading process with 400-grit silicon-carbide paper, then dry by slowly wiping through with a gauze sponge. Finish with 320 grit on most steels and 400 grit on aluminum alloys. Using a 4H pencil (on aluminum) or a ballpoint pen (on steel), burnish (do not scribe) whatever alignment marks are needed on the specimen. Repeatedly apply M-Prep Conditioner A and scrub with cotton-tipped applicators until a clean tip is no longer discolored. Remove all residue and Conditioner by again slowly wiping through with a gauze sponge. Never allow any solution to dry on the surface because this invariably leaves a contaminating film and reduces chances of a good bond.

Now apply a liberal amount of M-Prep Neutralizer 5A and scrub with a cotton-tipped applicator. With a single, slow wiping motion of a gauze sponge starting within the clean area and wiping outward in one direction. Repeat the wiping step with a clean gauze pad, again, start in the clean area, wipe though the gage location moving outward in a single stroke to fully dry this surface. Do not wipe back and forth because this may allow contaminants to be redeposited.

For proper results, the procedures and techniques presented here should be used with qualified Micro-Measurements installation accessory products. Those used in this procedure are: