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.
Coating layer thickness is a critical output parameter for paint and coating application processes. Insufficient thickness of a primer layer can result in delamination or disbonding. Insufficient thickness of a basecoat or color layer can negatively impact color, while insufficient thickness of other layers such as clearcoat can affect appearance. Excessive thickness can result in material waste, sagging, solvent popping, or in the case of plastic car bumpers with crash avoidance sensors, interference in the operation of the sensor for certain metallic paint coatings.
High resolution ultrasonic thickness gauges perform thickness measurements of one or multiple layers of paint and coatings on virtually any substrate type. Substrates include automotive steel and aluminum body panels, plastic bumper and trim components, wood, composite materials such as carbon fiber and SMC (Sheet Molded Composites), and glass.
Figure 1 Pulse Echo Layer Thickness Gauge (PELT) by BYK-Gardner
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.
Figure 2 Micrograph cross section of a 4-layer filmbuild on steel with PELT waveform output side by side.
Figure 3 Intermodal shipping container.
Figure 4 Wind turbine blade
Figure 5 PELT measurement on aluminum wheel.
[1] ASTM E797: Standard Practice for Measuring Thickness by Manual Ultrasonic Pulse-Echo Contact Method