Additive manufacturing: Cheaper, faster, better?

Additive manufacturing has been gaining in importance in the industrial sector for around ten years now. Sintering processes, new FDM technologies and printers the size of entire warehouses have developed from what once were small Cartesian printers. In the meantime, technology is regarded as a kind of panacea in many industries - but this technology is not going to be for some time yet. A current stocktaking:

Processes for any material
At the beginning of the research, only plastic parts came from 3D printers. Fused deposition modeling allowed the application of individual layers of different plastics, such as ABS, PLA or PET. By using special printing nozzles, the same printers can now print filaments of all kinds, for example, with wood fibres or rubber-like offset material. Even abrasive material with carbon fibre additives can now be printed.

SLA printers do not use filaments, but they rely on a special liquid (resin) that hardens when exposed to a special laser. Due to the very precise focusing of the light beam, objects produced by using the SLA process are usually printed more accurately.

In principle, DLP technology works in a similar way: A resin is also used here. However, a DLP projector that just about exposes every individual pixel is used as the light source. Therefore, the accuracy of the created model depends on the resolution of the DLP projector.

The SLS method (selective laser-sintering), which is particularly successful in the professional sector, processes various metals and ceramics. Instead of a liquid or filaments, the material of the starting product is processed in powder form. A laser melts the raw material and forms it in this way.

The most common materials can be printed with all different methods. From simple plastic parts to metal structures right up to products for aeronautics, a large variety of objects can be created. In the meantime, additive materials have often passed the prototyping phase and are used in the real world.

Milling or machining technology is also partly rendered obsolete through printing. Instead of machining large metal blocks and removing large quantities of chips, additive techniques only use as much material as is actually needed. This saves on raw materials and energy.

A large-scale project

One of the best-known projects in recent months is a printed bridge in Amsterdam: Four SLS printers produced the structure, which spans around 12 metres, completely autonomously. More than 4.5 tons of material were used in the experiment; the construction took six months. Originally, the bridge was to be built directly on the waterfront, but due to technical difficulties, the structure was manufactured in a large hall.

This project shows in which direction additive manufacturing is going: As well as being used for rapid prototyping, also large objects are produced by robots instead of people. As a result, the technology loses the reputation of being able to print only the smallest elements. The installation space changes from a cubic assembly space to an almost unlimited area - at least when power supply and material replenishment are available.

Dubai as 3D printing capital

In addition to processing metals, printers are also suitable for forming larger structures out of concrete. In some countries, experiments are being conducted with additively manufactured accommodations that are significantly cheaper and more stable than comparable dwellings.

Dubai is particularly noteworthy: In the United Arab Emirates, houses are comparatively often produced by printing. The rich city wants to further promote the production process and build 25 per cent by using the 3D printing process. The construction costs are to be reduced by around 70 per cent. The construction takes only a fifth of the time.

The construction of such complex structures requires highly automated robots that can move around the room as flexibly as possible. The development is progressing every day: After cubic printers, robot arms were used as in the case of the first printed bridge; the first technologies promise autonomous systems on wheels or chains.

3D printing is and will remain special

Despite all the advantages: 3D printing is not a complete substitute for common methods. Injection moulding processes will continue to have their raison d'être in the future, especially in mass production. It is true that the production of a mould is expensive. However, if the quantity is higher, it makes more sense to use the tried and tested method, both in terms of time and money.

There is still a lot of work to be done on larger projects before 3D printing can replace ordinary construction. Only highly specialised companies are able to print buildings. In addition to the hardware, special software is needed that still has to cope with teething troubles. Conventional methods are also superior when it comes to statics. Printing reinforced concrete is not (yet) technically possible.