New radar and terahertz technology finds needle in haystack
Investigations have shown that the radar and terahertz technology developed at SKZ can not only detect blowholes, but also quantify bulk density, determine average cell size and even localize non-foamed areas.
Laboratory setup for terahertz analysis, consisting of transmitting and receiving antennas and the foam product in the middle (Photo: SKZ)
Radar and Terahertz Technology for the Analysis of Foamed Plastics
The goal of the radar and terahertz technology developed at SKZ was to reliably detect small defects in foamed plastics. The samples examined were foamed plastics up to one meter thick, which could not be inspected non-destructively and 100% with any other technique. It turned out that, thanks to optimized optics and sophisticated signal processing, even shrinkage cavities as small as 1 mm can be detected independently of the user. However, while shrinkage cavities have fundamentally different material properties than the surrounding material, making their detection plausible, a serendipitous discovery showed that even a non-foamed granule - surrounded by many decimeters of foamed plastic - can be imaged.
As a result, both technologies can not only visualize the smallest bubbles inline, quantify the bulk density and determine the average cell size, but also localize non-foamed areas. First pilot plants at customers also show that the technology can detect the degree of foaming, which enables plant control. It is particularly noteworthy that the above-mentioned quality assurance options are even material-independent: It almost does not matter what kind of plastic it is. These possibilities make terahertz and radar technology unique on the market.
SKZ has long been involved with both methods for use in the plastics sector. The institute now also offers its own commercial products. It supports its customers from the selection of the appropriate non-destructive testing method to the fully operational, inline-capable measuring system. Interested companies can also carry out cost-neutral suitability tests.
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