Printing wagons with additive manufacturing

Louise Smyth

Rails of Sheffield (Rails) is a leading global retailer of railway modelling products based in the UK. It also manufactures specialist, museum-quality, niche products for collectors under its own label. Its ethos is simple: these products must be researched, designed and produced solely in the UK.

Rails wished to create a series of models that not only satisfied its market in terms of price, but also in terms of longevity and durability. Key to the success of these models would be the ability to include a level of detail that would be impossible to reproduce through injection moulding; and the ability to minimise the number of parts included in the assembly of the product.

The challenge of additive manufacturing

The company believed from the start that additive manufacturing could provide the solution to its needs. However, common desktop technologies used by the hobby market to 3D print models could neither deliver on the detailing required, nor on the economies of scale for producing models in quantity.

Having explored a range of additive manufacturing options, Rails discovered that Carbon Digital Light Synthesis technology was available in the UK through Paragon Rapid Technologies, a product development support company based in the North East. The Rails directors and their manufacturing partner, Dapol, met with Paragon in November 2018 to explore the opportunities for production that Carbon technology could offer.

Steps to success using additive manufacturing

The first step in the process was to test what was achievable. Carbon’s technology is designed to print multiple parts in one build, and the greater the efficiency in use of build space, the more cost effective the build will be when it comes to producing large numbers of product.

Paragon and Rails started the venture with a design that aimed to print the wagon in one piece. However, it quickly became clear the necessary support on the build platform could not be achieved without compromising aesthetics and detail. The two companies spent the next few months improving the design for manufacturability. The result – a three-piece unit comprising roof, body and chassis, all sitting within each other – delivered on optimum production efficiency (and therefore economies of scale) and detailing to the smallest rivet.

A rigid polyurethane, RPU 70, was chosen as the most suitable material for printing the first 800 wagons. With similar mechanical properties to the injection moulding material, ABS, RPU 70 gave Rails the ultimate combination of cost effectiveness and the robustness required to withstand constant use.

Rails sold all 800 wagons within hours of the product launch. The success of this first production run has resulted in a two-year schedule of new wagons, carriages and engines, with an ongoing cycle of design, sampling and production.

Digital Light Synthesis enables end-use production in a wide range of materials, from robust, recyclable polyurethanes to silicone rubbers. The technology has already demonstrated clear production advantages in the medical, industrial and automotive sectors; and for Paragon, this partnership represents a foundation stone in its additive manufacturing offering for consumer products.

Léonie Hilsdon is with Paragon Rapid Technologies

Top image courtesy of Peter Chandler

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