QUANTUM Terahertz Wall thickness measurement for the extrusion industry

Interview given by Ralph Klose (Manager R & D iNOEX GmbH)

 

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Based on a long experience and revolutionary ideas, iNOEX has for 30 years developed systems and solutions precisely tailored to the specific requirements of the pipe, profile, cable and film extrusion industry. Being a leader in innovations, iNOEX presents for the first time – a spectacular world novelty – a Terahertz wall thickness measuring system for plain pipes, corrugated pipes and foam pipes. Wavelengths between microwaves and infrared waves offer numerous options for applications.

We have talked to Ralph Klose, manager R & D of the traditional German company iNOEX about what producers can expect of the new Terahertz wall thickness measuring system QUANTUM.

Mr. Klose, since 1984 iNOEX has had an ongoing impact on the measuring and control technology in the plastics industry through an exceptional innovative strength. The new Terahertz wall thickness measuring system QUANTUM is in your handwriting. Which are the advantages Terahertz offers to producers and which were your development targets?

Ralph Klose: Decisive for the direction our technical work on Terahertz technology has taken was a physical property of Terahertz regarding its dependence on temperature. When temperatures change by 10 °C, the measurement error is only approx. 0.001 mm which is far below what other measuring systems are able to do. This means that the calibration of measuring values is largely not required in practical use.

Another decisive advantage of this new technology is the non-contact measuring principle, e.g. a coupling medium such as it is used for ultrasonic measurement is not required. This makes the system usable for a wide variety of applications. Auxiliary extrusion equipment which is normally needed for different product dimensions is no longer required.

Another interesting aspect in favor of our investment into this technology was that Terahertz waves are long waves with a non-ionizing wave length. Contrary to x-rays, Terahertz does not involve any health risk. This permits an extensive use of this fascinating optical technology.

Successful products make complicated procedures as easy as possible. For this reason the simple handling was important to us during the development of the QUANTUM system. Besides the advantages on the measuring and the mechanical side, this new technology offers a completely new course regarding the operating unit.

Terahertz wall thickness systems feature a new 21’’ terminal unit with a state-of-the-art software structure. The operator is able to use either a standard configuration or to configure his own operation concept based on so-called “widgets” such as they are used on tablets or smartphones. Additionally to the numerical and graphical display of actual measuring values, the system offers trends or statistical data and various interfaces. One of the innovative features is the new inoTREND, a very simple way to visualize production and process values by „multi-touch“. Process data and production times to be displayed can be individually adapted by the user. Further, each system is equipped with a TeamViewer Client for remote sessions which can be carried out easily and without any complex configuration.

Given the said advantages, why did you not focus on Terahertz wall thickness measurement much earlier?

Ralph Klose: Terahertz is an optical technology and it is in between the frequency range classically occupied by microwave technology and the infrared frequency range. The main problem to use this Terahertz frequency range was the production of suitable transmitter and receiver systems – also known as the “Terahertz gap” in the electromagnetic spectrum which made this technology completely unusable or usable only to a very limited extent. This is exactly where iNOEX has started research and development activities. As a result, compact and reasonably priced transmitter and receiver systems are now available which offer a sufficiently high output power for wall thickness measurement. Equally, powerful and inexpensive evaluation electronics and evaluation software are now available to configure this product.

Could you give us some details as to how an optical system measures non-transparent plastic materials?

Ralph Klose: Physics is very helpful here. Normal plastic materials such as PE, PP and PVC are transparent materials for Terahertz, comparable to glass in the visible frequency range.

iNOEX presented the new Terahertz wall thickness systems for the first time on the K’13. Which progress has been made technology-wise since then?

Ralph Klose: The main aspect of the further development of the QUANTUM systems is that we use reversing sensors for smooth pipes. Contrary to the information gained by static systems, the producer gets an information on the wall thickness distribution for the full 360° pipe circumference and not only for 4, 6 or 8 spots. Thus, in large-pipe applications which are produced at a slow speed this technology comes close to 100 % coverage. Presently, 4 standardized systems are available for smooth pipes, for dimensions from 10 – 1000 mm.
When the QUANTUM system was developed, we wanted it to have a large working range right from the beginning. QUANTUM 1000 is therefore able to measure pipe diameters from 250 to 1000 mm and wall thickness sizes up to 70 mm. Another main point for the Terahertz components was to increase the measuring frequency which will enable us to enter into new markets which are very promising for the future.

Which new markets do you have in mind?

Ralph Klose: Presently we supply exclusively gravimetric systems to the corrugated pipes market. QUANTUM offers for the first time the possibility for an inline measurement of wall thickness sizes of corrugated pipes. On account of the high measuring frequency, a sufficiently high number of measuring points can be gained on the pipe crown and in the pipe valley to perform a precise measurement. When the pipe crown is measured, even the two plastic material layers and the air layer can be individually defined and displayed. Many corrugated pipes are extruded together with the bell and the spigot, in a single work process. In this case it is very important for the producer to measure the interior diameter of the bell and the exterior diameter of the spigot, particularly in order to avoid unnecessary scrap. QUANTUM is able to perform this task because it is able not only to measure wall thickness sizes but also diameters. This data on product quality is then registered in a corresponding SQL database.

Any other markets you intend to enter?

Ralph Klose: Producers of foam core pipes are in a very competitive price situation. An efficient production process which uses as little material as possible is therefore an essential aspect. The difficulty lies in the precise tuning of the exterior layer, the foam layer and the interior layer. Conventional wall thickness measuring systems frequently fail due to high foaming grades or due to their non-profitability because of high acquisition costs. QUANTUM Terahertz systems are able to precisely measure foam core pipes, all three layers individually. Like this, the producer is for the first time able to precisely measure and possibly correct the important interior layer. The interplay with a gravimetric system can be automated on the base of a weight per meter control.

What prospects do you see in this technology?

Ralph Klose: The first months after we started our trials under production conditions have shown us the enormous potential of this new technology and with this its great perspective. The mere possibility to precisely measure EVOH layers in a PE compound offers enormous opportunities. Frequently, the layers in a COEX compound can be defined individually if they have different refraction indices. We also see a good potential for this technology in the film extrusion business. Here we have carried out some very promising trials. The development target in the film extrusion process is not only to define the overall wall thickness but also individual functional layers.

Have you had any feedback on this new technology from the experts in the plastics industry?

Ralph Klose: The feedback during and after the K’13 was formidable. We were contacted by all the different sectors of the extrusion industry. We were able to choose from a large variety of projects for the installation of our first reference systems.

Which developments can we expect from iNOEX for the K’16?

Ralph Klose: Details have not yet been specified, naturally, but we will of course continue our work on the QUANTUM system and on how we can open up new business segments with this promising new technology. At any rate, Terahertz has got the potential to advance us very far. We will continue to consistently follow the path of gravimetric system solutions and to realize additional value-added potential for our customers. Further, this year we will present a new gravimetric weigher generation for poorly flowing materials. For ultrasonic wall thickness measurement we will set the focus on innovative solutions, particularly for large-sized pipes.

Mr. Klose, thank you for this interview.

Ralph Klose
M.Sc. Dipl.-Ing. (FH)
Leiter Forschung & Entwicklung

iNOEX GmbH
www.inoex.d