Extrusion Asia Edition 2-2024

and the film bubble must only be a few tenths of a millimeter. To achieve this, an air cushion is often created in the area of the measuring electrode by means of fine holes and the thickness sensor is pressed into the film. Especially when measuring the thickness of sticky or surface-sensitive outer layers, this method leads to bubbles or marks on the film surface. In addition, with such materials, the bubble is poorly stabilized by a non-contact calibration cage and the thickness sensor often loses contact with the film surface, resulting in zero measurements at these affected positions. As a unique selling point, KCS offers a type of thickness gauge in which the sensor head follows the fluctuating film surface by means of a linear motor. This guarantees high-precision thick- ness measurement, minimizes the volume of compressed air needed to generate the air cushion and allows the control of the air cushion temperature. This temperature control of the air cushion reduces haze marks on high-gloss films, for example, in the best possible way. In 2010, KCS introduced the KNC-400 film thickness sensor, which works according to the above principle, to the global market. For the first two years, this sensor was mounted on a reversing device with telescopic radial adjustment and sold as a film thickness gauge with the designation KNC-400 Rotomat Synchro and KNC-400 Rotomat Vario. Since 2012, it has been mounted on the reversing device with articulated arm cross- beam with the model designations KNC-400 Rotomat KT 2G and KNC-400 Rotomat KT 3G. Since the market launch of the KNC-400, the feedback from the hundreds of thickness sensors in daily production use have been incorporated into change requests for product improve- ments. Most of these have been implemented, but the KNC- 400 still corresponds conceptually to the original development ideas. Over the last decade, the output rates of blown film lines have multiplied and the demands on film quality – also for the rea- son to reduce the amount of raw materials used – have increa- sed enormously. KCS's mission is to enable the global film extrusion industry to a high quality, resource-saving and reliable production. This mission statement obliges KCS to adapt its product range to the new customer requirements and five years ago launched the project for the new development of all thickness sensors based on the capacitive measuring me- thod. The first step was to meticulously analyze the service and repair cases associated with the KNC-400 sensor over the past few years and incorporate these findings into the specifications for the new development of the successor sensor with the desi- gnation KNC-401. A great deal of attention was paid to impro- vements in terms of robustness, electromagnetic compatibility, modularity, reduction of compressed air consumption and the manufacturing and testing process. During the entire develop- ment cycle, the newly evaluated, externally procured compo- nents were subjected to various stress tests and, if necessary, replaced with other, more robust components. Prototypes were tested in the best possible way on our in-hou- se facilities and then handed over to selected end customers and OEMs for use on blown film lines. Based on the in-depth prototype tests, a pilot series of KNC-401 sensors was produc- ed. Devices from the pilot series production were then put into daily production use at various film manufacturers and this ex- perience was in turn incorporated into the series production of the KNC-401 sensors. The market launch of this new generation of capacitive thick- ness gauges has been delayed due to the pandemic and the subsequent procurement crisis. However, the time has now co- me and the KNC-401 sensor will be the first product available to the global market from the end of 2024 and will be sold as a new device with the designation KNC-401 Rotomat KT 3G. Thanks to its backwards compatibility, the KNC-401 sensor can also replace the predecessor model on existing measuring sys- tems. The vision of KCS is to be the world's most trusted gauge manufacturer for film extrusion. The company firmly belie- ves that with the market launch of the KNC-401 sensor they are contributing to achieving this vision. KCS will also bring the remaining capacitive thickness sensors of the latest generation to production maturity as quickly as possible and distribute them to the global customer base. ➠ KÜNDIG CONTROL SYSTEMS (KCS), HCH. KÜNDIG & CIE.AG Joweid Zentrum 11, 8630, Rüti ZH, Switzerland www.gauge.ch www.smart-extrusion.com 30 测量技术 ，吹膜 Extrusion Asia Edition 2/2024