Is a non-destructive testing technique developed specifically for the inspection of non-conductive (dielectric) materials, such as plastics, elastomers, ceramics, fiberglass, composite materials, or others.
Its operation is based on the concept of electromagnetic wave interferometry. A sensor emits a microwave beam that, by scanning the component being inspected, generates reflections where there are changes in the permittivity (dielectric constant) of the material. In this way it is capable of detecting defects such as cracks, delaminations, folds, wrinkles, holes and even changes in the molecular structure of the material due to aging, chemical attacks or UV radiation.
The microwave techniques is both a qualitative and a quantitative method. In fact, if required, it allows thickness measurement at any point of the scan performed.
It currently has an enormous growth potential in practically all industries as it brings solutions to unsolved inspection problems.
The tool is highly portable and consumes very little power (5mW) so this is completely safe for people. In addition, using a double encoder allows to take readings and reference them in a X vs. Y plane. The scanner can be adjusted to any type of surface; cylindrical from 2 inches in diameter or flat, and communicates wirelessly with a notebook.
Conventional inspection techniques such as ultrasound or radiography are used in dielectric materials by adoption and/or habit, but they do not offer 100% reliable results since the defects that affect this type of material are poor acoustic reflectors, so they do not generate ultrasonic echoes, nor do they significantly change the density of the materials, that is, they are difficult to detect with radiographic inspection.
There are several applications of the method. For example, if applied to inspect HDPE pipe joints, the microwave method allows to determine (following ASTM standards) the state of the union, identifying several different types of anomalies , including the main defect in this type of joints, cold fusion.
When Applied to inspect fiberglass tanks, the Micro wave technique identify internal defects with excellent accuracy, while only accessing the external face of the equipment.
Image obtained by external inspection of a fiberglass container in which previous repairs on the equipment and new defects that need repair can be identified.
Photograph taken from inside the equipment, prior to its repair.
When the MW system is Applied to windmill blades, one can evaluate internal arrangement of the different layers of material, observing, for example, excess or lack of resin, even wrinkles in the internal volume of the piece that act as stress concentrators and can generate delaminations that could lead to catastrophic failures during operation.
