As a pewter foundry, DJH are specialists in casting from pewter - a high quality, precious metal known for its unique properties including exceptional corrosion resistance and durability. In addition to pewter, they are also able to incorporate a wide range of other materials as requirement by the project – including rubber, plastic, nylon, brass and steel.

www.djhengineering.co.uk

DJH were tasked with manufacturing scale models of the 1980 JCB 3CX Sitemaster and the Terex Titan Dump Truck. Each unique design needed to replicate their full-scale counterpart down to the finest detail. 

J Coker Ltd had supplied DJH with centrifugal silicone casting discs for over 20 years. Knowing that Cokers were also tool makers and rubber moulders, DJH Engineering approached them to help with the production of replica rubber tyres for both projects.

DJH were able to provide excellent in-house drawings of each of the three tyres needed. Each tyre was detailed with replica tread, tyre pressure information and logos.

Coker’s converted the files into a CAD file format, setting the designs into tooling blocks for cutting on our HAAS tool room mills. Each file is re-sized to take into account the shrinkage in rubber when it is moulded.

The detail of the treads was replicated by spark eroding. This process requires a copper electrode to be cut. The electrode is then used to gently spark the profile into the steel tool where ordinary milling cutters cannot reach.

The fully assembled tools are then set up in any of Cokers range of Panstone automatic moulding presses. Moulding temperatures, cure times, pressure and materials are trialled to mould the perfect tyre.

“Cokers really helped us out with these projects. Speaking to their design team allowed us to more closely understand the processes they use, which meant we could adjust our design to reduce tool making time and improve productivity. 

We have been very impressed with the tyres. Our client says the tyres really help lift the Terex Titan model above other models. We’re looking forward to the release of our 1980 JCB 3CX Sitemaster this year, the soft tyres really create some realism thanks to the weight of our brass and pewter model.”

www.jcbexplore.co.uk