Manufacturing processes in 3D printing, relevance on the classic car parts market

Additive manufacturing and the classic car spare parts market

When we talk about 3D printing, we often hear a lot of obscure terms like additive manufacturing, laser sintering and FDM. This article gives an insight into current 3D printing processes, their procedure, surface quality and special features.

Additive manufacturing describes a process in which the material is applied layer by layer. This distinguishes it from conventional processes in which material is removed. As a result, the amount of material can be determined more precisely and smaller series can be produced, e.g. spare parts for vintage cars.

Another advantage is the high degree of customisation. One is able to print very complex shapes and does not need any additional tools. In particular, spare parts for motorbikes or cars whose production has long since ceased can be reproduced. Especially for rare or hard-to-find spare parts, 3D printing is the ideal bridge.

Additive or generative manufacturing includes several processes such as stereolithography, selective laser sintering, fused layer modelling or laser beam melting. In order to manufacture parts, a 3D CAD model must be created beforehand.

In the following, we explain the basis on which the different processes work:

FLM – Fused Layer Modelling

The process is also called “Fused Filament Fabrication” (FFF) or Fused Deposition Modelling (FDM). It works similar to a hot glue gun controlled by a computer. A wire-shaped plastic or a plastic mixture is pressed through a heated nozzle by means of a conveyor unit. This liquefies the plastic, which is then applied in layers. With the help of this technique, it is possible to produce solid or hollow bodies with layer thicknesses between 0.025mm and 1.25mm. It is thus possible to produce knobs, seals (even for vintage cars), add-on parts and trims and to rework them as desired. Of course, the originality and quality of the spare parts is particularly important. Here, too, the technology can meet the high demands due to its wide range of materials available for the FDM process. Thermoplastics such as polyethylene, polypropylene, polylactide, ABS and PETG, but also material mixtures with metals, carbon fibre or carbon are possible depending on the requirement profile and the required strength. A purely metallic structure is obtained by subsequent sintering.

SLS – selective laser sintering

In laser sintering, a powder is applied to a surface layer by layer. The powder is selectively melted by a laser beam, which is controlled by a mechanism, and then solidifies again. The energy supplied by the laser is absorbed by the powder and triggers localised sintering of particles.

The powder can be metal, plastic or ceramic powder, but mixed forms are also possible. The process takes place under increased pressure and is characterised by so-called “process lighting”. Process lighting is the targeted brightening of contours that the laser scans. This is how a Mercedes star can be given a new shine. The effect of the beams also makes it possible to create undercuts that could not be produced with the classic casting process for plastic materials. A major advantage of SLS technology is that it does not require any support structures, as the component is always surrounded by powder during production. However, this powder must be removed again afterwards.

SLA – Stereolithographie

The SLA process is the oldest of the 3D printing processes. It is characterized by the fact that the component is in a bath of liquid photopolymer. Photopolymer is a plastic cured by UV rays, such as acrylic or epoxy resins. The contours of the component are solidified layer by layer by a laser. A lifting unit lowers or raises the component and a squeegee distributes the resin evenly. After the component is finished, the resin must drip off and the component may need to be placed in a UV oven to cure.

The SLA process stands out especially for its surface quality and high precision. It can be used to produce very thin layers. For the production of complex components, support structures are required, which in turn have to be removed mechanically.

All of the technologies described are already being used in the 3D printing of spare parts. How you get from your template or desired spare part to the finished component is described in more detail in our article “The path from template to 3D printed spare part”.

Please also feel free to visit our other articles on the topic of 3D printing and reconstruction for vintage and classic cars.