Dave Darby, based in Teesside, came to TWI to explore possible applications for the new material Dartech they have created and patented. TWI carried out an initial review of the capabilities of the new material and this led to the idea of using it for quick, low-cost prototype tooling.
Dartech is a foundry technology, producing tool-room accuracy and has been successfully tested at 70kg/cm 2 tensile strength. The new compound is sand-based and once heated is very hard, making it ideal for jigging and tooling. Some initial work had been done to produce simple injection-moulding tools and it was thought that this could be taken further to make tooling for holding objects during operations such as drilling and cutting.
During a Feasibility Study carried out under the Joining Forces North East programme, TWI suggested using Dartech to produce welding fixtures for components. The components were put into the sand mixture which was hardened off to produce a cavity profile. The tools were then made and used to hold injection moulded plastic samples in place while they were welded using vibration welding. A number of trial welds were carried out and no deterioration was detected in the tooling.
Dave Darby was please with the results and has also had successful trials with tools for vacuum forming. He is now looking for other potential applications and customers to exploit further this hard-wearing, low cost material.