Extrusion International 3-2019

34 Extrusion International 3/2019 MEASURING TECHNOLOGY Terahertz – iNOEX Technology sets Industrial Standard InterviewwithM.Sc. Ralph Klose, Director Technology iNOEX GmbH: “Systematic further development of Terahertz technology“ 30 years of practical experience inmeasurement and control in the extrusion technology which has always included the creation of revolutionary ideas and patents are the distinguishing features of iNOEX GmbH. Being one of the first movers in the field, iNOEX recognized the benefits of the new key technology Terahertz / millimeter waves at an early stage and has during the past 8 years developed it into a pioneering technology which is now ready for use in industrial environments. The products QUANTUM andWARP define the technological standard of Terahertz / millimeter waves for the pipe extrusion industry withmore than 150 systems currently in the market Mr. Klose, please explain to us what is understood by Terahertz technology? Ralph Klose: Terahertz technology is based on an electromagnetic wave be- tween 100 GHz (0,1 THz) to 10 THz. In the electromagnetic spectrum you will find it between infrared and micro- wave radiation and it offers a number of significant advantages of the adja- cent ranges. When electromagnetic waves are generated in this specific fre- quency rangeandcorrespondingtrans- mitters and receivers are established, non-conductive materials such as e.g. plastic material can be measured. Plas- tic materials are almost transparent for Terahertz waves, therefore non- destructive and non-contact product testing becomes possible. The move- ment of a THz wave through plastic material is braked by a difference in the refraction indexes. This difference cre- ates a reflexion of the wave caused by the transition zone between different material types (e.g. air, PE). The transit time of the reflected echos is the infor- mationwe are looking for. We use it to determine the wall thickness of each M.Sc . Ralph Klose, Director Technology iNOEX GmbH: “Our innovative capacity lies with our staff and their special know-how. InMelle, 35 engineers are employed in our R&D department.“ layerwith an accuracy of a fewmicrom- eters. The refraction index is the mate- rial-dependent calibration value which defines the transit time in the material. Our WARP systems do not have to be calibrated manually as these systems are able to self-calibrate automatically and continuously. An important fea- ture for extrusion processes where ag- gregates such as carbon black or calci- umcarbonate are added in an unstable process. The term “millimeter waves” is often heard, does this term relate to the same measuring principle? Klose: Yes indeed, this term describes the same measuring principle. The frequency range of millimeter waves overlaps with the Terahertz range in the lower frequency area and fea- tures are almost the same. iNOEX uses both ranges for different applications. Summarizing, one can say: the higher the frequency and the wider the fre- quency, which is used, the smaller the layers (e.g. EVOH) which can be measured. However, this comes at the expense of the maximummeasur- able layer thickness – lower frequen- cies are an advantage. Due to the fact that iNOEX is able to cover the frequency ranges of both Terahertz and millimeter waves, we decided for Terahertz (THz) as the uniform term. „Millimeter waves“ is used as a mar- keting term. You have already mentioned some of the advantages of Terahertz technol- ogy. Are there others, too? Klose: This technology naturally com- petes with other measuring princi- ples, such as e.g. ultrasound or X-ray. Compared to measurement by ultra- sound, Terahertz does not require any coupling medium which means that measurement is contact-free. Besides, measuring is independent of the tem- perature of the measuring object. Compared to X-ray, Terahertz is based on non-ionising radiation and is there- fore not harmful to health. This fact re- ally facilitatesmounting conditions and there is no need to engage a radiation protection supervisor.