Plastics take over from metal in engineering

Plastics take over from metal in engineering
By John Whitehead

An innovative UK injection moulder has developed an all-plastic method of joining concrete tunnel segments that can weigh up to 12 tonnes.

The patented technology from Bosworth Plastics in Hinckley will be on display at the Underground Construction show this month and is already being supplied on two contracts.

The Dowelock system is the latest brainchild of entrepreneur Peter Robertshaw and his associate, freelance tunnel design consultant Chris Smith. It achieves a priority in tunnel design by eliminating the use of metal in the system used to hold the segments together. In addition, it speeds up the installation process, thus reducing costs.

The component is a showcase for engineering polymers employing two DuPont materials – Delrin 100 acetal resin and Zytel 70G30 nylon – plus ABS. The application has to combine easy installation with resistance to enormous pull-out forces.