Among the technologies slated to disrupt conventional automotive manufacturing practices in the near future, 3D printing might well be on top. Also known as ‘additive manufacturing,’ 3D printing is already being used by automotive OEMs, including car, motorcycle and CV manufacturers, to transform the way visualise, design and build products. The technology allows OEMs to work in-house during the prototyping stage, thus ensuring greater confidentiality, while also making for greater creative freedom, flexibility and the opportunity to reduce production costs.
Industrial 3D printers, including the ones used for automotive applications, often work with 3D drawings created with CAD software, using those drawings to create actual physical objects. This is done by converting CAD drawings to create files that 3D printers can ‘read’ and use to create 3D objects in layers or ‘slices,’ by laying down multiple layers of material (usually advanced engineering plastics, which can in some cases be substituted for metal) and building objects via a series of three-dimensional cross-sections. This technology allows OEMs to increase prototyping speeds, especially since 3D printers can even create complex shapes with fully functional moving parts.
Indeed, 3D printing has the potential to cut down the time for producing a full-scale model (or specific part or component) from weeks to just a few hours, which can be hugely beneficial for OEMs. Currently, the technology is more useful for low-volume components that may otherwise be expensive and/or complicated to produce, with the coming of cheaper, faster and more advanced 3D printers, 3D-printed parts are likely to hit mainstream usage as well.
TECHNOLOGIES AND APPLICATIONS
Until about 5-6 years ago, 3D printing was primarily used to create one-off concepts for showcasing to a specific audience, but now with the capability to make complex functional models that are also durable, 3D printing tech is being used by some automotive OEMs for a range of functions, including design development, prototyping, testing for collision resistance, vibration and shock absorption etc., and advanced validation. Using engineering-grade thermoplastics like ABS and Polypropylene to create 3D-printed objects, engineers can understand in advance how the final product will perform, before an OEM goes in for mass production.
Some OEMs actually prefer direct digital manufacturing (DDM) over conventional manufacturing processes, especially for specialised, low-volume applications. DDM uses 3D printing technology to produce parts directly from CAD files, without machining, moulding or casting. While subtractive fabrication processes like machining or forging can involve the removal of material for creating a component, DDM produces the same part(s) by taking the opposite path, where material is added layer by layer. The method is ideal for creating objects that have complex, intricate geometries and are hence relatively difficult and/or expensive to produce using conventional production processes.
One of the leaders in this space is Stratasys, a US-based company that was set up in the late-1980s and which currently makes 3D printers and production systems for prototyping and manufacturing applications. Stratasys’ fused deposition modelling (FDM) technology, which the company pioneered in the early-1990s, helps manufacturers create durable components using advanced thermoplastics. FDM has been used to create concept models, functional prototypes and even fully functional parts using engineering materials like ABSplus, polycarbonate and Nylon 12. FDM, a professional 3D printing technology that produces parts with a high degree of mechanical, thermal and chemical strength, works via softening the thermoplastic filament by heating it, and then extruding the same according to required, pre-set coordinates, which results in the component being created in layers from the ground up. Even shapes with hollow interiors can be created using this technology, since FDM is able to deposit removable support material that acts as ‘scaffolding.’ This material can be removed by hand or by dissolving in a suitable solvent solution. FDM’s claimed benefits, as compared to using conventional CNC machining methods, include increased toughness, electrostatic dissipation, translucence, biocompatibility, UV resistance and better VO flammability ratings, which makes it ideally suited for various industrial applications, including automotive applications.
Among materials used in 3D printing applications, Nylon 12 is supposed to be one of the toughest thermoplastics in the industry, with fatigue resistance that’s better than any other engineering thermoplastic. Another high performance thermoplastic for automotive usage is ULTEM 9085, which is FST (flame, smoke, toxicity) certified, while some others include ABS-M30i, PC-ISO, ASA, ABS-ESD7FDM and ULTEM 1010.
Apart from FDM, there’s also another popular 3D printing technology that’s widely being used – PolyJet technology, an ink-jet based additive manufacturing technology which is accurate, versatile (in terms of the building materials that can be used) and, since it provides a smooth surface finish, enables designers to showcase final-product aesthetics. With PolyJet tech, it’s possible to create complex shapes with intricate detailing, at very high layer resolution (up to 16 microns). It also allows the usage of triple-jetting technology, which can combine up to three different materials for creating parts that require multiple colours and/or textures.
With PolyJet 3D printing technology, the printer’s jets lay down layers of liquid photopolymer in the required shapes, which are then ‘cured’ by UV light. Fine layers of photopolymer material accumulate to finally create the required 3D model, which can also contain removable gel-like support material if required. This can later be easily removed and washed away. PolyJet technology can use various materials, including certain grades of rubber and various plastics, which can also be combined, as per physical qualities required, in terms of strength, flexibility, heat resistance, fit and finish, and texture etc.
Set up in the late-1990s, Israel-based Objet Geometries Ltd. currently offers high-resolution PolyJet 3D printing solutions. The company launches its first multi-material 3D printer – the Connex500 3D – about a decade ago, and have continued to build better, more advanced 3D printing solutions since then. In fact, Stratasys Inc. and Objet Geometries Ltd. merged in 2012 to become Stratasys Ltd., which is now a world leader in 3D printing solutions for various industries.
Global automotive industry analysts say that 3D printing in automotive applications will be a $ 1.1 billion annual market by 2019, and while additive manufacturing has primarily been used for prototyping activity, this will rapidly expand to include doing multiple design iterations, building sets of components for fit-and-finish checks, and production of functional parts for testing and validation. Furthermore, 3D printing may also supplant traditional subtractive production methods, for the creation of vehicles that are built using a hybrid process. With direct digital manufacturing, OEMs hope to be able to build cars with fewer parts, eliminate expensive tooling and offer more extensive options for customisation.
With 3D printing, the time saved in the prototyping stages in turn reduces turnaround time across subsequent stages of manufacturing, which adds business agility and helps eliminate wastage. While domestic automotive OEMs like Mahindra have just started exploring options in the realm of 3D printing, some other global OEMs have already been using this technology for quite some time. General Motors, for example, uses various 3D printing technologies, including selective laser sintering (SLS) and stereolithography (SLA), for its design, engineering and manufacturing processes, as well as for parts prototyping. Chrysler and Ford also use 3D printing, with the latter being one of the earliest adopters of this technology, running as many as five 3D prototyping centres globally. Ford, in fact, actually uses 3D printed parts (including intake manifolds and cylinder heads etc.) in its test vehicles, thereby successfully saving on castings and tooling costs.
Companies are now also making advances in terms of materials used for 3D printing processes, moving from silica powder, resin and sand, to increased use of engineering plastics that can be transparent at times, allowing engineers to visualise operations inside out. Not just that, some manufacturers like BMW and Johnsons Controls Automotive Seating are even beginning to use metal compounds for 3D printing, using SLM technology, which allows certain 3D printers to print complex metal parts that might be difficult to produce using traditional methods.
One of the biggest challenges in 3D printing is speed, which can be significantly slower than what is achievable with more traditional processes. So, while OEMs can still consider 3D printing for specialised, low-volume components, using this technology for high-volume mass-market parts is often not feasible. With advances in technology in recent years, industrial 3D printers can now print larger objects than before, but speed is still a constraint.
However, over the next few years, the automotive industry is expected to take cues from other industries – including aerospace and defence – and make further investments in developing additive manufacturing processes, which will include the willingness to experiment and work with newer materials as well. There is progress happening in all areas globally, with different companies taking different approaches to how they think they can use 3D printing technology to their advantage. BMW, for example, using 3D printing tech to build hand-tools for vehicle assembly and testing, while Daimler uses it to produce replacement and small series production parts for its buses and for Mercedes-Benz trucks (at greatly reduced turnaround times, helping customer outreach in a big way), and yet other OEMs are just beginning to get in on the act in smaller ways, but with a view to increased usage over the coming years.
While 3D printing will help OEMs in the areas of faster prototyping and low-volume specialised production of components, it can also have other benefits, including working on multiple design iterations and vehicle lightweighting. In the UK, engineers have done some significant work on additive manufacturing processes by exploring the potential to use 3D printed structures and sub-assembles that may help reduce vehicle weight. Among other initiatives, this includes working with aluminium lattice structures made with 3D printing tech, which may lead to significant weight reduction and subsequent improvements in fuel efficiency.
Over the coming years, 3D printing techniques may lead to improved fuel economy, reduced vehicle weight, reduced material wastage, and reduction or elimination of the requirement for specialised tooling. Last year, Aston Martin showcased 3D printed parts for the twin-turbo V12 engine used on the DB11, Mercedes-Benz is making extensive use of additive manufacturing to produce replacement parts for its commercial vehicles and the 2018 S-Class luxury sedan is expected to use some 3D printed parts, Ford is said to be saving millions of dollars by using 3D printing tech, Mitsubishi is beginning to experiment with DDM and even a high-end supercar manufacturer like Koenigsegg uses some 3D printed parts for its One:1 supercar. With the coming of electric powerplants and autonomous cars, which are likely to anyway demand a sea change in traditional manufacturing practices, the future definitely looks bright for this technology.
TEXT: Sameer Kumar