Additive Manufacturing – a snapshot

There is hardly an article on future technology which does not involve the terms of either “additive manufacturing” or “3D printing”. To many people, these terms are associated with the famous replicator from Star Trek – a black box able to make almost everything imaginable. And while there isn’t quite yet a device just like the Star Trek replicator, research and development is certainly heading in this direction. Both terms involve a large variety of underlying technologies and applications, some “up and coming”, some already established and undoubtedly some that will still be science fiction for a while yet. However, an estimated market volume of $5 billion in 2016 and forecasted growth rates of more than 20% (Wohler Associates Inc.) demonstrate that this is already a serious business.

The terms “3D printing” and “additive manufacturing” are sometimes used interchangeably but “additive manufacturing” (AM) is the more general term and includes any technology which builds systems from the bottom up by the addition of material to an existing structure – this can include the sintering of ceramic materials at the intersection of two laser beams, the building of houses using robots dispensing concrete and even the knitting of shoes. 3D printing is a subset of AM technologies which refer to actual printing (e.g. dispensing a molten polymer in order to build up a 3 dimensional structure). Some of the technologies under the umbrella term “additive manufacturing” are very established (rapid prototyping using 3D printing technologies has been around for at least 20 years). Some are still in their infancy, such as the printing of carbon fibre composites. What does get engineers excited is the increasingly widespread availability of these technologies and the pace of their development.

The main advantages of additive manufacturing are the ability to produce customised parts, as well as producing small volumes without the costly process of producing moulds. Hence the “classic” application for additive manufacturing / 3D printing is the making of prototypes – somewhat ironically often mould prototypes. However, 3D printing technology is also an established means of production for a few other niche applications, such as the manufacture of hearing aids, customised models of teeth to fit braces, and bicycle accessories. Applications in food are popular in the media, such as the ability of restaurants to print customised pasta shapes, a project Barilla has been working on.

When 3D printers of polymers became easily available, a service industry of small businesses emerged offering on-demand production as well as personalisation. These 3D printing bureaus can be B2B businesses offering production of customised parts or prototypes for the manufacturing industry, but some are reaching out into the consumer goods sector by offering bespoke products such as jewellery, figurines or even furniture. Many of these latter companies have established themselves as a virtual workbench where small series of products can be produced or designs can be traded.

With advances in metals processing, applications in the aerospace have also emerged, and Airbus is now one of the key stakeholders. The specific advantage for these applications is the ability to produce geometric structures that would otherwise be impossible to achieve – allowing for very durable but lightweight parts.

A lot of money is also going into the investigation of printing customised medical implants, prosthesis and even skin.

The ability to produce products on demand is expected to lead to the manufacture of replacement parts for products ranging from cars to vacuum cleaners. This carries the promise of reduced inventories of spare parts, as the part needed could either be printed, or indeed a blueprint of the part could be sent to an outlet anywhere in the world, saving warehouse and shipping cost and reducing waste. A recent real-life example was the 3D-printing of mains water pipe connectors after the Nepalese earthquake: it meant that mains water pipes could be re-connected in a fast and efficient manner, saving days of misery waiting for spare parts.

Examples of additive manufacturing technology used in mass produced consumer goods are hard to come by. Recently Tamicare, a UK company, signed an agreement with a major sportswear brand to additively manufacture textiles – garments of multiple materials can be “printed” without sewing or cutting, including the manufacture of whole shoes. Another company, Aprecia, uses a 3D printing technique to produce medication which dissolves easily in water. The 3D printing technique is able to manufacture pills with an internally porous structure which would be impossible to achieve with conventional methods.

However, additive manufacturing is not going to be the answer to everything: it is an intrinsically slow process – even though speeds are increasing it is unlikely to ever be a technology able to compete with high volume production processes such as injection moulding. Similarly, some materials and products are currently not 3D-printable, as the layer-by-layer process can lead to intrinsic defects and therefore instabilities in the parts. In fact for the currently available “home 3D printers” only very few polymers and polymer grades are suitable – a fact exploited by the industry which follows a “razor blade business model”, selling the certified printable polymers at a premium price compared to non-certified similar resins. In time, it is likely that the more widespread availability of 3D printing will threaten the current incumbents and lead to a further decrease in the cost of printers and materials. Evidence of disruption can be seen by RepRap, a successful concept of an open source 3D printing hardware aimed at hobbyists, and emerging examples of the use of recycled plastic for 3D printing applications.

In the meantime the authors look forward to having a little replicator in their kitchen to make them the perfect pasta shape they always wanted or bake them the ultimate birthday cake for their next children’s party.

 

Britta Kleinsorge and Daniel Wustenberg

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