WCA November 2019

The most common coating variant for LV power cables, tandem extrusion, is increasingly being replaced by so-called co-extrusion. This is mainly for two reasons: the production process is more efficient and more cost-effective for the manufacturer, and it is becoming inevitable due to the many different extrusion materials. The new crosshead RX 40 MB 2.1.I from Rosendahl was specially developed for these requirements. It enables the co-extrusion of different material combinations, such as EPDM with PVC. Cables, especially in the field of building cabling, have ever thinner and optimised wall thicknesses. These products require a high degree of precision in their manufacturing process. During the development of this new crosshead, Rosendahl made special efforts to ensure that commercially available products can be processed from a diameter of only 3mm. The head is also liquid-tempered, which means that, if necessary, very low plastic melt temperatures can be processed. Due to thermally separated material flows, materials with different melt temperatures can be extruded. These properties are particularly important for the production of flame-retardant materials, such as LS0H. Another advantage is the separately heated head zones. As a result, the required production temperature can be controlled better, and constantly monitored during production. This achieves stable process conditions for the entire production time, even with changing processing temperatures. Benefits include: • Easier to use due to co-extrusion • Material savings thanks to the possible processing of thinner filler wall thicknesses • Prevent problems by eliminating an additional intermediate cooling path and cable drying Rosendahl Nextrom – Austria Website : www.rosendahlnextrom.com The new co- extrusion-crosshead from Rosendahl Technology news

Electrophoretic painting for the protection of metal parts

❍ The end results and electrophoretic paintline

William Hughes has introduced an electrophoretic paintline at its Plovdiv factory in Bulgaria. This paintline provides a high gloss black finish with strong anti-corrosive properties and is intended mainly for use on the springs, wire forms and assemblies manufactured by William Hughes, but can also be offered as a service to other manufacturers. Electrophoretic paint – or E coating – is a combination of plating and painting whereby a metal object is dipped in a water-based solution, which contains a paint emulsion. An electric current passes through the part causing the paint emulsion to condense onto it. Both the outside of the part and any internal surfaces can be painted, provided the solution can reach the surface concerned. Typical coating thickness is 20 to 22 microns but upwards of 40 microns can be achieved if required. Many of the parts produced by William Hughes are destined for use in the automotive seating industry for which the paint chosen is particularly suitable due to its anti-noise properties. Cleaning is the first step in the process, using an alkaline cleaning agent for the removal of oil, grease and other surface contaminants prior to a rinse in tap water. This is followed by an acid bath for more stringent cleaning, then further rinsing and a passivation procedure designed to remove any remaining iron contaminants from the surface of the material. A rinse in de-ionising water prevents bubbles forming on the surface of the part when it enters the electro painting, or KTL stage. The paintline transfers the parts from tank to tank fully automatically in a closed loop system that eliminates waste and is both efficient and environmentally friendly. The painted parts are then cured in an oven set at 200º for 20 minutes, and will withstand corrosion for around 800 hours, according to tests conducted in William Hughes’s salt-spray testing facility. William Hughes Ltd – UK Website : www.wmhughes.co.uk

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Wire & Cable ASIA – November/December 2019

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