Multi-layer Film Thickness Measurement
PELT technology leverages ultrasound to measure Pulse Echo Layer Thickness, setting a global standard for high-resolution, multi-layer precision thickness measurements. PELT is a non-destructive, high-resolution instrument, enabling precise paint process control by measuring every layer individually and simultaneously.
Paint and Coating Layer Thickness is a Critical Measurement
Image 1 Pulse Echo Layer Thickness Gauge (PELT) by BYK-Gardner
Principal of Operation
High resolution ultrasonic thickness gauges such as the BYK-µPELT series of gauges, are in essence acoustic microscopes, providing a one-dimensional cross-sectional image through a point on a surface. Whereas an optical microscope discriminates layer boundaries via the differences in optical properties of the coating or paint layers being measured, an acoustic microscope senses the differences in mechanical or acoustic properties of the coating or paint materials.
An ultrasonic thickness gauge functions by sending an extremely short ultrasonic pulse into the top coating layer. At the interface between each pair of coating layers, a portion of the ultrasonic pulse will be reflected back to the sensor. The remaining portion of the ultrasonic signal will continue to propagate through the subsequent layers. Each time the ultrasonic signal crosses the interface between a pair of layers having differing mechanical or acoustic properties, an echo will be generated. The interval of time between echoes is proportional to the thickness of each coating.
Image 2 Micrograph cross section of a 4-layer filmbuild on steel with PELT waveform output side by side.
Measurement Applications
- Multiple layers of coatings on automotive steel and aluminum body panels.
- Automotive plastic bumpers and other automotive trim components.
- Primer and topcoat systems for construction equipment, railroad locomotives and rolling stock, and high-speed railway equipment.
- Wind turbine blade coatings, shipping container anti-corrosion and topcoat coatings, and marine coatings.
- Paint coatings and lacquers on wood such as cabinetry, furniture, musical instruments, and flooring.
- Laminate coatings and layers.
Image 3 Intermodal shipping container.
Image 4 Wind turbine blade
Image 5 PELT measurement on aluminum wheel.
Standards and Literature
[1] ASTM E797: Standard Practice for Measuring Thickness by Manual Ultrasonic Pulse-Echo Contact Method
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