Digital Light Synthesis™ (DLS) technology (sometimes called DLP) uses a photochemical process to project light through an oxygen-permeable window into a reservoir of UV-curable resin. The resultant parts are layer free with consistent, isotropic and predictable mechanical properties. The most fabulous thing about DLS is that there is a huge range of tough, durable temperature resistant, chemical resistant resins (both hard composites and soft rubbers) that are suitable for production parts; and this technology is so sophisticated that textures can be printed onto the surface – intricate detailing that would probably have been added by hand in days gone by.
Multi Jet Fusion (MJF) is similar to Selective Laser Sintering in process. However, like DLS, it is an additive manufacturing process designed for scaled-up production. Printing in PA 11, or PA 12 nylon, parts are tough, durable, heat and chemical resistant. They can also be dyed and finished to a satin sheen.
Part by Part
Do plastics and composites really have a part to play in vehicle restoration? Perhaps not in pre-war classics; but from about 1930, plastics started to be used. It was a new concept and perhaps one that hadn’t really been thought through. Many early plastics were not the heat resistant, chemical resistant polymers available today; they would be brittle and crack quickly when exposed to heat or cold. It didn’t stop even the prestige manufacturers exploiting the economic benefits, though, and you’ll find bits of (broken) plastic both under the bonnet and on internal trim and dashboards.
Under bonnet parts that can be replaced in this way include plastic windshield-washer fluid bottles, brake fluid tanks, cable insulation, battery boxes, points covers, fluid manifold components, nozzles, dampers, air intake filters, gears, bushes, cams, bearings, weatherproof coatings, the list goes on…
Come to your interior trim and you’re looking at dashboard backings, buttons, housings, knobs, levers, carpet stud covers, badges and even lenses.
If that wasn’t enough, for parts that need to be cast, scanning and 3D printing the part first will enable your friendly caster to create a master pattern for building his casting and moulding tools.
The key to restoration, however, is getting the part exactly right in shape and size. And the parts you want to replace may well be in many pieces. And you’ll need the exact dimensions to create the CAD for printing. There are automotive archives where original drawings of a multitude of parts of a multitude of makes and models can be found. The Rootes Archive Trust in Wroxton and the Institution of Mechanical Engineers may be able to help here. Most 3D printing service providers should be able to offer you the option to turn drawings into CAD. Or they will at least will have a friendly CAD expert just a phone call away.
In the absence of drawings, it may be quicker, and possibly cheaper, to find a service provider who offers reverse engineering. Using a laser scanner such as a FAROArm, they will be able to turn the physical into digital and create new CAD for the parts. If your part is in several pieces, it can be glued back together at the digital interface.
Next, discuss with the 3D printer the most suitable options for recreating the part. Not all composites and resins are created equal, and there are a variety of simulants available. As described above, technological advantages will also need to be taken into consideration here. If your part requires a high tensile strength, and needs to be heat resistant, but doesn’t have intricate detailing, you could consider a composite printed part using fused filament fabrication (FFF). Alternatively, you might need an intricately detailed, complex, rigid component part to be produced that does require a high heat resistance. In this instance, Digital Light Synthesis™ technology could possibly be the answer. DLS is also great for printing rubberised switches and knobs.
Once you’ve decided upon technology and material, and have sent the CAD to your printer, you can be sure that you’ll have your part back in a matter of days rather than weeks.
We hope that the brief insight we have provided into the merits of additive manufacturing for automotive restoration is enough to convince you that it’s worth a punt. To summarise, metal and plastic 3D printing of parts and tooling are helping to bring rare spares to the collector sooner, and cheaper, than ever before.