Extrusion International 5-2017

11 Extrusion International 5/2017 Ultra-thin core insulation and minimized microphonic effects Among the variety of new products to be exhibited by specialty cable manufacturer HEW-KABEL of Wipperfürth, Germany, at the SPS IPC Drives (November 28-30 in Nurem- berg) are a modified PTFE (polytetrafluoroethylene) for ultra-thin yet highly resistant in- sulations and the HEW-SILENT technology, also based on PTFE, for minimizing microphonic ef- fects when transmitting low signals. The new modified PTFE from HEW-KABEL combines for the first time outstanding perfor- mance properties with reliable processability even in the case of extremely small dimensions. Its mechanical strength and electrical insulating strength exceed those of conventional PTFE with the same wide ser- vice temperature range (+260 °C to –190 °C), the same high temperature and chemical resistance, and unchanged good high-frequency properties (permittivity and dielectric loss factor). This means that the new specialty PTFE is suitable for the production of insulations that can be made very much thinner than was previously possible, but without making any compromises on application properties. The potential is shown by a pilot application in the form of a multi-core cable for the harsh oil production environment. By switching to the new modified PTFE, HEW-KABEL was able to reduce the thickness of the insulations from their origi- nal 0.16 mm to 0.10 mm, which thus permitted the specified 10% reduction in the cable diameter. Furthermore, the new cable offers almost double the flexural fatigue strength than the previous design – without any change in cross-section, dielectric strength, chemical resistance or tensile strength. The HEW-SILENT technology developed by HEW-KABEL makes a considerable contribution to avoiding microphonic effects in signal cables and thus to an optimized signal in- tegrity, for example in medical and measurement technol- ogy. Such effects can occur with cables under mechanical load when a conductor or screen rub against a non-con- ductor. The resultant electrical charges can, despite their small size, be so troublesome that they overlay the equally small useful signals. The HEW-SILENT technology minimizes the occurrence of such electrical charges and is suitable for www.hew-kabel.com both coaxial cables and for paired and multi-core cable con- structions. The basis of this technology are conductive tapes based on PTFE with a particularly homogeneous surface resistance in the low Ohm range. To manufacture them, the company has developed a special production line that enables the strin- gent quality requirements to be continuously met. Apart from that, the in-house production allows a large amount of versatility with regard to the design and dimensions for a variety of different products, with which, because of the very good plasticity, even complex geometries like the surface of a cable shield can be replicated. Thanks to the in-house de- velopment of special technologies, HEW-KABEL can also ap- ply very thin conductive layers with a high level of uniformity. The effectiveness of the HEW-SILENT technology is shown, for example, in its use for a twisted-pair wire in which the microphonic effect was lowered from a critical 1.4 pC – with the same wire design – to an outstanding 0.2 pC (approxi- mate figures). As a result, accompanying measures became superfluous.