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Additive manufacturing, commonly known as 3D printing to many people, is a revolutionary technique which can print many types of materials into pre-determined 3D geometries. There are many industries that now utilize 3D printing and the automotive industry is one of these. In this article, we look at the various types of materials used to create car components using 3D printing methods.
3D printing is now used to create many parts of a car. To date, 3D printing has been used to create up to 75% of a whole car and there are plans to increase this to 90%, and beyond. However, it is only used to create prototypes at the moment, and not road worthy vehicles (on the whole, although some parts are an exception). That being said, many F1 teams are looking to create vehicles which will eventually be used on the track. 3D printing is also used in the automotive industry for custom parts and the re-manufacturing of components.
The main materials used in the 3D printing of cars are plastics, metal and composites. We now take a look at these in more detail.
There are a wide range of 3D printed plastics used in automobiles, and plastics are used more than any other material in 3D printing methods within the automotive industry. There are three common methods of 3D printing plastics – selective layer sintering (SLS), fused deposition modelling (FDM) and stereolithography (SLA).
Acrylonitrile butadiene styrene (ABS) filaments are one of the most common plastics used for 3D printing car components and are often used within the bodywork of a car. ABS is usually 3D printed using FDM processes.
It is a useful material for bodywork applications because it is an elastomer-based thermoplastic that is both flexible and resistant to shock. It is also a tough material that can withstand temperature ranges of -20 to 80 °C – well within the range of temperatures that a car will be subjected to. It can also be easily welded and is a reusable material.
Polylactic acid (PLA) is a biodegradable material commonly manufactured using renewable raw materials. PLA is one of the easiest materials to 3D print and no heated platform is required. This is different to ABS, because ABS both requires a heated platform and is non-biodegradable.
Even though PLA can print at a low temperature, it is much harder to manipulate than other materials. PLA is commonly printed using FDM techniques and can be produced in a wide range of colours.
Polycarbonate materials are widely known for their high strength, high temperature and ability to resist physical deformation. At temperatures above 150 °C, polycarbonate will deform, therefore high printing temperatures are required. It is as not as widely used as other polymer materials, as the layers can separate out at lower temperatures and are prone to absorbing moisture.
Polyamides are a semi-crystalline polymer that offer a high level of detail, stability, rigidity, flexibility, and shock resistance. Polyamide itself is granular powder, but for automotive applications, its fibrous form (nylon) is commonly used. Polyamides are produced using FDM and are often 3D printed for use as gears, among other parts in the automotive market.
Among other industries, polypropylene is used for the 3D printing of parts in the automotive sector. Polypropylene is a thermoplastic polymer that possesses a high resistance to abrasion, a high ability to absorb shocks and a useful ratio of rigidity and flexibility.
However, pure polypropylene is sensitive to both UV rays and temperature, which can cause it to expand. Because of the high exposure that these components come under during manufacturing and usage, many companies now print with alternative types of polypropylene. These possess a much better physical and mechanical properties than standard polypropylene, making them more suited for automotive applications.
Metal-based 3D printing is relatively new to the automotive industry but is gaining more traction. Techniques to print metals include Gauss gun-inspired magnetohydrodynamic print head, powder bed, electron-beam printing and wire-feed electron-beam printing.
Deposition of metals includes both pure metals, such as aluminium, and metal alloys. Prior to printing, the metal, or metal alloy, has to be melted. As metals melt at high temperatures, lasers are required. Once the metal has been turned into a liquid, layers of molten metal can then be deposited and allowed to solidify. Whilst the processes are mainly used for producing small volumes of spare and prototype parts, many manufacturers believe that they could become more widely used in the future.
Carbon and glass fiber composites are commonly used in the 3D printing of car bodyworks. Printing with fibrous materials produces composites with very high strength characteristics, especially as the internal structures can be tailored and optimized. Carbon fibers are often composited with many of the polymers mentioned above. Aside from polymers, carbon fibers can be used with resins. By compositing materials with carbon fibers, parts can be made that not only possess a high strength, but can also be lightweight, flexible or heat-resistant.
There are also many plastic-based composites used in the automotive industry. Some of these are plastic-only composite mixtures, but others are mixed with wood filaments to create a more organic texture. Metals can also be used in conjunction with polymers to create metallic materials with a classy-looking finish.
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