Ultrasonic thickness gauge for composites – SAUT6100D-SW

The ultrasonic thickness gauge for composites is a graphic instrument designed for non-destructive thickness measurement of fiberglass and selected composite or low-density materials. Unlike ultrasonic thickness gauges that are developed primarily for homogeneous materials or metallic substrates, this model uses a dedicated low-frequency probe that is better suited to materials with more complex ultrasonic-wave propagation characteristics.

Fiberglass thickness measurement is one of the instrument’s main applications. In marine applications, it allows the thickness of hulls, bulkheads, panels, tanks and composite components to be measured from one side of the component, eliminating the need for destructive sampling or sectioning. This is useful both during production and during maintenance inspections, where the condition of the structure must be assessed while preserving its integrity.

The ultrasonic thickness gauge for fiberglass can also be used on selected composites such as carbon fiber, compatible plastics and certain low-density materials such as polyurethanes. However, composite materials do not all respond to ultrasonic waves in the same way. Factors such as fiber orientation, laminate construction, core materials, geometry, surface finish and overall composition can significantly influence signal transmission and measurement stability.

For this reason, applications involving carbon fiber, laminated structures or particularly complex composites should always be verified in advance on an actual customer sample. Preliminary testing helps evaluate signal quality, determine the material’s actual measurability, and identify the most suitable setup before recommending the instrument for a specific inspection application.

The A-scan function displays the echoes of the ultrasonic signal detected at the measurement point. In addition to the thickness readings, this graphical view helps the operator assess signal behaviour and investigate indications or anomalies that are consistant with delaminations, discontinuities or internal defects in the composite material, for example on a fiberglass hull.

It is important to note that the A-scan function is an aid to interpretation rather than an automatic defect detection system. In composite materials, signal analysis depends on factors including material structure, geometry, probe selection and inspection procedure. The instrument can therefore be used for targeted checks and to identify areas requiring further investigation, but the validity of the inspection must be defined according to the actual application.

The B-scan mode provides a graphical representation of thickness variation along a scan of the component. By moving the probe over an area of the structure, the operator can observe thickness variations, identify localised differences, and assess the inspected profile more effectively. It is particularly useful for panels, tanks, hull surfaces, and composite components where thickness continuity needs to be evaluated across a defined area.

The specified measurement range applies to fiberglass, the material for which this model has been specifically designed. Its 0.01 mm resolution supports detailed thickness inspections, while functions such as minimum value capture, difference calculation, averaging and limit functions help organise and manage inspections across different components and inspection areas more effectively.

Minimum and maximum alarm thresholds make it possible to set inspection limits and quickly identify values requiring attention. Internal memory allows readings collected during inspections to be stored, while the data output enables connection to software for measurement collection, improving traceability and reducing transcription errors in quality-control processes. On this model, cable and software are included as standard.

Compared to the graphic ultrasonic gauge for metallic materials, including coated components, the ultrasonic thickness gauge for composites addresses a different inspection requirement. It has been developed specifically for non-homogeneous materials such as fiberglass and selected compatible composites. Rather than serving as an alternative for through-coating measurements on metallic substrates, it is a dedicated instrument for applications where ultrasonic wave propagation requires a specific probe configuration and a careful assessment of the material characteristics.

The instrument is used in the marine sector for inspecting fiberglass hulls and components, in the production and maintenance of composite tanks and pipelines, and for the inspection of panels and compatible plastic structures. It is also suitable for automotive and aerospace applications where composite components can be measured using this technique. Its use is particularly valuable when thickness measurement needs to be combined with graphical signal visualization to support the investigation of potential material anomalies.

The ultrasonic thickness gauge for composites is designed for non-destructive inspections on fiberglass and selected compatible composite materials, with the ability to document readings and analyse the ultrasonic signal directly on the instrument. For specific materials, preliminary testing on a sample helps identify the most suitable inspection approach and avoid applications that are not compatible with the component structure. A calibration report can be supplied upon request.

Applications

• Non-destructive thickness measurement of fiberglass components
• One-sided thickness inspection of hulls, bulkheads and composite marine components
• Verification of tanks, pipelines, panels and structures made of fiberglass
• Inspection of selected carbon-fibre components, subject to prior verification on an actual sample
• Assessment of compatible plastic materials and low-density materials suitable for ultrasonic measurement
• Inspection of composite components in automotive and aerospace applications
• Display of ultrasonic signal echoes using A-scan mode
• Further investigation of indications compatible with delamination, discontinuities or internal defects in composites
• Analysis of thickness variation along the area using B-scan mode
• Verification of localised thickness variations on panels and extended surfaces
• Inspections with minimum and maximum alarm thresholds
• Management of readings through internal memory, cable and supplied software
• Preliminary sample assessment for laminated composites or materials with a particular structure
• Inspections supported by a calibration report available upon request

FAQ – Ultrasonic thickness gauge for composites

What is an ultrasonic thickness gauge for composites used for?
It is used to measure the thickness of fiberglass and selected composite or low-density materials that are compatible with ultrasonic measurement, without damaging the component. It is suitable where the inspection must be performed from one side only, without cutting or sectioning the part.

Why is this model specific to fiberglass and composite materials?
It is equipped with a dedicated low-frequency probe designed to work on materials whose ultrasonic response differs from that of the homogeneous materials normally measured with standard thickness gauges.

Can it measure every type of composite material?
No. Composite materials can have very different structures, lay-ups and ultrasonic behaviours. Fiberglass is the main application for this instrument; for carbon fiber, laminated materials or particular composites, measurement feasibility should be verified in advance on an actual sample.

Can it be used to inspect fiberglass hulls?
Yes. It is suitable for checking the thickness of hulls, bulkheads, panels and other fiberglass components from one accessible side of the structure. The graphical functions can also help investigate possible signal anomalies detected during inspection.

Can it be used on carbon-fiber components?
It can be used on selected carbon-fiber components, but measurement feasibility must be verified on an actual sample. Ultrasonic response can vary according to the lay-up, fiber orientation and component structure.

What is A-scan mode used for in composite inspections?
A-scan mode displays ultrasonic signal echoes at the measurement point. It helps assess the quality of the thickness reading and can support the investigation of indications or anomalies compatible with delamination, discontinuities or internal defects in the composite material.

Does the instrument automatically identify every delamination or internal defect?
No. Graphical signal display can help identify anomalies requiring further investigation, but the inspection depends on the material, component structure, probe used and applied procedure. For critical applications, the method must be defined and validated on an actual sample.

What is B-scan mode used for?
B-scan mode represents thickness variation along a scan of the component. It is useful for observing variations along panels, hulls, tanks or other composite surfaces and for identifying areas with different thicknesses.

What is the difference compared with the graphic thickness gauge for metallic materials?
The graphic thickness gauge for metallic materials is intended for inspections on metallic substrates, including beneath paint or insulating coatings. This model is instead specific to fiberglass and selected composite or low-density materials, thanks to its dedicated probe for signal propagation in non-homogeneous materials.

Can it also measure plastic materials?
It can be assessed for plastic or low-density materials compatible with ultrasonic-wave propagation, such as polyurethanes. In these cases, the application should also be verified on the actual material where component characteristics are not already known.

Are cable and software included with the instrument?
Yes. Cable and software are included as standard and allow collected measurements to be organised, improving inspection traceability.

Can a calibration report be requested?
Yes. A calibration report can be supplied upon request to document the instrument’s metrological control within company procedures for managing measuring equipment.

Want to learn more?
If you’d like a detailed look at how ultrasonic measurement works and why the SAUT6100D-SW model is ideal for fiberglass and other composites, read our in-depth article here 👉 Ultrasonic Graphic Thickness Gauge – SAUT6100D-SW