Measure Surface Roughness Without Contact
Non-contact roughness measurement is the only option when the part has undercuts, threads, grooves, or any removal constraint that would lock a Rigid impression in place.
Recommended Product
Use F30 Visual for most non-contact surface inspections. It is a Flexible Fluid product that extracts easily from complex shapes and produces a glossy black impression that makes surface defects, scratches, and roughness peaks easier to see on a suitable instrument.
When to Use F30 Visual
- The shape has undercuts, threads, or grooves.
- You have a non-contact roughness measuring instrument.
- This instrument is not a white-light interferometer.
When F30 Visual Is Not the Right Choice
White-light interferometers work best with light-colored products. Because F30 Visual is black, it absorbs light and gives poor results on this type of instrument.
If you are using a white-light interferometer, choose one of these products instead. Run a test with a Plastiform expert before you buy.
- F20, a Flexible Fluid product, light green.
- F40, a Flexible Fluid product, white.
- F85, a Rigid Fluid product, light gray, only when the shape has no removal constraint.
Ra, Rt and Rz
A P80 Ra impression is a good indicator of Ra when you read it with a contact roughness tester. For Rt or Rz values, use a non-contact measuring device instead. You can also read a P80 Ra impression with an optical inspection device, provided the shape has no removal constraint.
Step-by-Step
- Degrease the surface with DN1 and wipe it dry with a clean microfiber.
- Choose the product that suits your instrument.
- Mount the cartridge on the dispensing gun, with a nozzle and a tip.
- Apply or inject the product so it wets the whole surface.
- Wait for polymerization.
- Extract carefully. Pull straight out without rotating. A Flexible impression deforms and springs back.
- Inspect the impression with your optical instrument.
Verification
Compare the image of the impression with a known good surface or a direct measurement on an accessible reference area. Repeat the impression if it shows tears, bubbles, or incomplete wetting.
Troubleshooting
| Problem | Likely Cause | Solution |
|---|---|---|
| Impression gives poor results on an interferometer | The black surface absorbs white light | Switch to F20, F40 or F85 for white-light interferometry or a similar technology. |
| Edges look distorted | Impression was extracted by rotation | Pull straight out without twisting |
| Bubbles in the inspected area | Product did not fully wet the surface | Degrease again and inject more slowly, starting from the deepest point. Keep the tip or nozzle in permanent contact with the surface so the pressure pushes the product into the details. |
