A better seal at a considerably lower cost was achieved by Toolcraft Plastics of Swindon, UK, when two steel valve seating rings were redesigned to be extruded in a tough plastic. Toolcraft chose polyacetal and tests showed the plastic to “give” a little, making an even better seal than the steel and at a far lower cost. Designing out the time-consuming process of cutting eight radial holes was crucial. The design achieved by Toolcraft also enabled the part to be made on one mould tool, the radial holes being produced without retracting cores which would have slowed the process and increased tool costs. Toolcraft’s redesign service includes choice of materials and can also incorporate restyling of a part to up-date client’s product.
