Additive Manufacturing: Which Route to Take?

It is hard to deny that developments in the 3D printing world are changing the way we look at design and manufacture in the Automotive sector. The market is fragmented, with low price 3D inkjet printers rendering the technology accessible for a wider audience at the budget end.

In 2009, the BfB RapMan became the first commercially available 3D printer, shortly followed by Makerbot Industries. Since 2009, further entry level machines have been launched, servicing the demand for basic rapid prototypes.

At the other end of the spectrum, significant improvements in printing accuracy, build speed and the progress made with material properties mean that its industrial applications are endless. However, choosing an appropriate 3D Printing technology for a particular commercial project can be a daunting task.

Weighing up a few of the options…

Having revolutionized the industry, Stereolithography (SLA) is considered the leading 3D printing process, where epoxy resin reacts with a laser beam and hardens to form extremely accurate solid parts layer by layer according to 3D data. Selective Laser Sintering (SLS) is another popular option, which utilises a laser beam to fuse powder particles together to reflect the 3D data supplied. However, probably the most widely used technology is Fused Deposition Modelling (FDM), which many entry-level machines still rely on today. FDM parts are formed through the extrusion of thermoplastic material, offering a good all round process that is mainly used by OEMs rather than bureaus, as less clean up equipment is required.

Precision and Material Selection

For rapid prototypes where high resolution is not a priority, FDM is the most common process. On the other hand, SLA and SLS are preferred if extremely tight tolerances are necessary to represent clear design features. With regards to their thermal and mechanical properties, groundbreaking materials are available across most AM processes, depending on the specific application. Where FDM’s front runner ULTEM 9085 offers a lightweight and flame retardant option, SLA’s trump card is WaterShed® 11122, which achieves excellent optical clarity when polished for lens and lighting applications. Where both FDM and SLA produce great functional prototypes, SLS is often preferred for functional end-use products where strong, durable components made from Nylon can withstand harsh environments. At this point, the simple 3D printing concept becomes Additive Manufacture (AM) for low volume production runs.

Geometry and Product Finishing

3D Print has revolutionised design, enabling increasingly elaborate, organic structures to be realised. In this respect, SLS is more effective for producing complex geometries than FDM, as the Nylon powder used is self-supporting and eliminates the need for additional structures as support for overhangs or undercuts within the design. When it comes to post processing however, SLS can sometimes require a greater level of effort to finish than SLA for example, which is most suitable for either fully finished master patterns feeding downstream processes, or as a one off prototype for marketing purposes when finished by expert model makers.

Speed and Economies of Scale

Its clear that developments across the AM spectrum have brought costs down, regardless of process. The nature of the industry means that affordability and fast turn-around are paramount for many, as costs are cut and speed to market improves competitiveness. In response, some rapid prototyping companies like Paragon now cater for urgent requirements with a dedicated 3D Printing department. Email 3DPrint@paragon-rt.com for more info.

The flexibility and superior mechanical properties associated with AM technologies can sometimes be offset by their higher material costs. When using these processes, users must also consider production quantity to ensure a commercially viable choice is made. For manufactured parts, it may be more sensible to look at Silicone Tooling and Vacuum Casting to bring unit costs down, especially if potential tooling costs could be amortised across the production run.

And the Winner is…

…dependent on your expectations of the model! Whether the intended purpose is as a visual concept, a functional prototype for testing, or for end use components, what you might think is the right 3D printing process for your part may not necessarily be the case. As a leader in its field, Paragon can offer advice on 3D printing for Automotive Rapid Prototyping and Low Volume Production applications. Call +44 (0)1325 333141 for more information.