Application Note | Composite Surface Inspection
Fiberglass Composite Surface Roughness and Flatness Using 3D Profilometry
Measuring the Roughness and Flatness of a Woven Fiber-Reinforced Polymer for Quality Control
Research & Experimental Testing
Craig Leising
Visual Design & Editorial
Andrew Shore
Introduction
Fiberglass is a material made from extremely fine fibers of glass. It is used as a reinforcing agent for many polymer products; the resulting composite material, properly known as fiber-reinforced polymer (FRP) or glass-reinforced plastic (GRP), is called “fiberglass” in popular usage.
Why Surface Metrology Inspection Matters for Fiberglass Quality Control
Although there are many uses for Fiberglass reinforcement, in most applications it is crucial that they are as strong as possible. Fiberglass composites have one of the highest strength to weight ratios available and in some cases, pound for pound it is stronger than steel. Aside from high strength, it is also important to have the smallest possible exposed surface area. Large fiberglass surfaces can make the structure more vulnerable to chemical attack and possibly material expansion. Therefore, surface inspection is critical to quality control production.
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Measurement Objective
In this application, the NANOVEA ST400 is used to measure a Fiberglass Composite surface for roughness and flatness. By quantifying these surface features it is possible to create or optimize a stronger, longer lasting fiberglass composite material.
NANOVEA ST400 Standard
Optical 3D Profilometer
Measurement Parameters
| Parameter | Value |
|---|---|
| Probe | 1 mm |
| Acquisition rate | 300 Hz |
| Averaging | 1 |
| Measured surface | 5 mm x 2 mm |
| Step size | 5 µm x 5 µm |
| Scanning mode | Constant speed |
Measurement parameters.
The fiberglass composite sample.
Probe Specifications
| Specification | Value |
|---|---|
| Measurement range | 1 mm |
| Z resolution | 25 nm |
| Z accuracy | 200 nm |
| Lateral resolution | 2 µm |
Optical probe specifications.
Results
False Color View
3D Surface Flatness
3D Surface Roughness
| Parameter | Value | Unit | Description |
|---|---|---|---|
| Sa | 15.716 | µm | Arithmetical Mean Height |
| Sq | 19.905 | µm | Root Mean Square Height |
| Sp | 116.74 | µm | Maximum Peak Height |
| Sv | 136.09 | µm | Maximum Pit Height |
| Sz | 252.83 | µm | Maximum Height |
| Ssk | 0.556 | Skewness | |
| Sku | 3.654 | Kurtosis |
Table 1: ISO 25178 roughness parameters of the fiberglass composite surface.
Conclusion
As shown in the results, the NANOVEA ST400 Optical Profiler was able to accurately measure the roughness and flatness of the fiberglass composite surface. Data can be measured over multiple batches of fiber composites and or a given time period to provide crucial information about different fiberglass manufacturing processes and how they react over time. Thus, the ST400 is a viable option for strengthening the quality control process of fiberglass composite materials.
Frequently Asked Questions About Fiberglass Surface Inspection
What is fiberglass?
Fiberglass is a material made from extremely fine fibers of glass, used as a reinforcing agent for many polymer products. The resulting composite, properly called fiber-reinforced polymer (FRP) or glass-reinforced plastic (GRP), is called fiberglass in popular usage.
Why inspect the surface of fiberglass composites?
Besides high strength, fiberglass composites should have the smallest possible exposed surface area: large fiberglass surfaces can make the structure more vulnerable to chemical attack and possibly material expansion. Surface inspection is therefore critical to quality control in production.
Which roughness parameters describe a fiberglass surface?
ISO 25178 areal parameters. The fiberglass composite measured here had Sa of 15.716 µm, Sq of 19.905 µm and Sz of 252.83 µm (Sp 116.74 µm, Sv 136.09 µm), with a skewness Ssk of 0.556 and a kurtosis Sku of 3.654.
How is a composite surface measured without contact?
A NANOVEA ST400 optical profilometer scanned a 5 mm × 2 mm area with a 1 mm range probe at a 5 µm × 5 µm step, producing a 3D map from which flatness and roughness are calculated.
How can surface data improve fiberglass manufacturing?
Data measured over multiple batches of fiber composites, or over a given time period, gives crucial information about different fiberglass manufacturing processes and how they react over time, helping create or optimize a stronger, longer lasting composite.
Which NANOVEA instrument measures composite roughness and flatness?
The NANOVEA ST400 optical profiler, here with a probe of 1 mm measurement range, 25 nm Z resolution, 200 nm Z accuracy and 2 µm lateral resolution.
