Plastic Insulator is Future for Rail

Using plastics as a replacement for metal is now commonplace. A combination of good design and material selection can meet the most exacting of demands. One such application is the insulator that supports the third rail supplying power to trains.

Allied Insulators Group supplies a wide range of insulators to the electricity, rail and telecommunications industries. The company has been supplying third rail insulators for more than 40 years with the original product being a solid porcelain insulator with a metal cap and flange base. The challenge for Allied Insulators was to remain competitive by developing a polymer replacement. To achieve this they approached Rutland Plastics for their help due to their expertise in demanding engineering applications. Rutland Plastics and Allied Insulators worked together on developing a suitable design. Once this design had been agreed, the material supplier, Sumika Polymer Compounds (UK), became involved. All three companies met to discuss the project in detail and Sumika suggested a suitable polymer and carried out a series of FEA (Finite Element Analysis) studies of the design to check its performance against the Network Rail requirements. Results exceeded expectations and only a few minor changes were needed. Test blocks of the proposed material were supplied by Sumika to enable Allied Insulators to assess the suitability of the proposed polymer compound. Rutland Plastics arranged for prototypes of the parts to be manufactured. These were purely to show the appearance of the product and demonstrate its versatility and ease of installation. On completion of tooling the final stage was the supply of parts for Network Rail to install on a test track. The new moulded third rail insulator passed with flying colours and is now into full production. The main advantages of this innovative solution over the metal and ceramic insulator are: • Lower Cost • Speed of manufacture • Easier installation • Lighter in weight • More vandal resistant • Less prone to breakage during installation • Can be adjusted for height to allow for rail wear • Can be rotated • 100% recyclable