Learn more about 3D-printing

Do you want to know more about additive manufacturing and 3D printing? Here is a breif introduction to the subject.

3D printers are used in architecture, the automotive, aerospace and defence industries, as well as in medical and dental care, where, among other things, implants and prostheses are produced using 3D printers. Advantages of additive manufacturing include:

• Possibility to print complex geometries at a lower cost
• Less material waste
• Mass customization, that is, production of several products that are all unique (such as earphones and dental implants)
• Prototyping, where time to market can be significantly shortened and costs reduced
• Catalysed innovation
• New potential applications for materials

All additive manufacturing begins with a digital three-dimensional drawing or shape, often created using CAD (Computer Aided Design) software. The 3D model is then “sliced” into thin sections, from a few micrometres to a few millimetres, depending on the technology and software used. The machine creates the component by depositing (printing) each slice of the model on top of the previous one until the model is complete.

3D printing takes place on a flat surface which – depending on the print technology used – can be raised and lowered during the printing process. Depending on the size of the object to be printed, the thickness of the layers, the material and the type of printer, the printing process can take anything from a few hours to several days.

With 3D printing, it is possible to manufacture very complex parts without the need for special tools or processing. Additive manufacturing has few restrictions when it comes to the complexity of the items produced, giving designers “free-of-charge complexity”, meaning that no matter how complex the design, the cost of printing will not be significantly higher. Free-of-charge complexity also allows for easy 3D printing of several simple components that together make up a very complex object that could not be manufactured using conventional techniques.

Will additive manufacturing and 3D printing completely replace injection moulding and rotational moulding? Absolutely not, and definitely not in the short perspective. 3D printers are not made for producing 100,000 buckets – that is a job for injection moulding. The main application for 3D printers is the production of tailored parts in small series, because they offer the possibility to create complex geometries without the need to manufacture tools for making a product; all you need is a 3D model created in a computer.

Prototyping has long been the most common use of 3D printers, but in recent years the technology has developed and is now increasingly frequent in industrial production processes.

Printing technologies

Here is a translation of a text from a web page of the Swedish National Heritage Board.

There are several different 3D printing processes, depending on the material and desired properties of the finished model. The most common technologies used in 3D printers for the consumer market are FDM (Fused Deposition Modelling) and Polyjet.

FDM

Fused Deposition Modelling (FDM) is the technology used in almost all 3D printers for the consumer market. It is also called FFF (Fused Filament Fabrication) or MPD (Molten Polymer Deposition). It is similar to the inkjet process, using print heads to build up the model layer by layer with thin threads of molten, liquid thermoplastic that is sprayed onto a platform and then hardens (solidifies) when cooling. The thread, which is usually between 1.75 and 3 mm thick, is pressed through a die between 0.25 and 0.8 mm wide, and fuses with the underlying layer. When the layer is finished, the platform is lowered so that the next layer can be deposited on top of it. The material used is normally a plastic thread on a roll, called a filament.

The advantages of this technology are that it is easy to handle and comes in a wide range of price segments, from basic consumer printers to advanced printers suitable for businesses.

About 70% of all printers in the market are FDM/FFF printers, thus using filaments as raw material. Most typically, plastic filaments are used, such as PLA, ABS, PETG or nylon. In addition, there are many different filament modifications, such as carbon fibre, wood, metal, aluminium, glass, luminescent and transparent.

A list of filaments and their properties (in Swedish) can be found at 3dguide.se.

The advantages of FDM technology are that it is easy and inexpensive, with the possibility of printing exceptionally durable materials that are also available in many colours, with a metallic surface as an option. The disadvantages are less appealing surface texture and poor detail reproduction due to low resolution and varying dimensional accuracy when basic consumer equipment is used. Some models may also require support structures for printing with this technology.

In the Circlab environment, there are several printers that use FDM technology.

Polyjet

Polyjet is a technology where small drops of two different polymers (thermoplastics) are deposited on a platform and then cured directly by means of UV radiation. One of the materials is the building material itself, and the other is a support material that can easily be removed after printing. This technology provides a smoother surface with better detail reproduction than for FDM models, where the layers are often visible.

The choice of materials is wide: thousands of different materials can be combined in one and the same model. The materials can be both coloured and transparent, but also rubber-like and flexible. But for models that are to be exposed to great physical stress, the durable thermoplastics used in FDM printing may be a better alternative. Thermosets, which are used for models in polyjet printing, unlike thermoplastics, cannot be remelted and converted into new products.

SLA

SLA, short for stereolithography, means that the printer creates models by curing plastic in liquid form, layer by layer, using a UV laser. There are consumer printers based on this technology, but they are not as common as FDM or polyjet printers.

The advantages of SLA are excellent resolution and detail reproduction, as well as the possibility of creating transparent models. The disadvantages are that it may be difficult to handle the liquid during filling and post-processing, some shapes require support materials, and the models require curing after 3D printing.

DLP

Digital Light Processing (DLP) is a technology much like SLA, but the plastic liquid is cured by a projector instead of a laser. The end results are similar, but the DLP manufacturing process is faster, with less material waste and lower operating costs.

SLS

Selective Laser Sintering (SLS) uses a laser to assemble the material, in the same way as for SLA. But here, the material is in powder form. Any material that can be produced in the form of a powder can (at least theoretically) be used to make models with this technology.

Common materials, besides plastics, are metals, ceramics and glass. No support materials are needed, the material properties are good and it is possible to create very complex geometries. This technology is not used in consumer machines, the handling of powder materials is demanding, and the costs of material are high.

CJP

Colour Jet Printing (CJP) is a powder-based technology. First, a layer of powder is deposited, whereupon a print head, similar to that of an inkjet printer, is used to apply a liquid that bonds the powder together in the right spots into a solid surface. The platform is then lowered, corresponding to the thickness of one layer, and then the step is repeated until the model is finished. Similar to SLS, this technology does not require any additional support material, making it easy to create complex geometries. A CJP printer can also use several colours at the same time. The main disadvantage of this technology is that models made of ceramic materials are very fragile.

Materials

The material and its properties have a substantial impact on the possibility of printing high-quality products in 3D printers, and different printers are adapted to different types of materials. The table below shows some criteria used to describe and compare materials:

For FDM printers (which use filaments), PLA and ABS are the most common materials today. There is also a wide range of alternative materials, such as nylon, PET and PETG. A list of filaments and their properties (in Swedish) can be found at 3dguide.se.

Metal printers are becoming increasingly common in companies and universities. There are a couple of metal powder manufacturers in Sweden (Uddeholm and Sandvik). Other materials used (for example, for large-scale printing or special components) are cement, sand, wood, ceramic materials and various types of biocomposites.

Research and development of new materials is considered one of the most important measures in order for additive manufacturing to make a broad breakthrough.

Trends and development

The trend is clear: the use of additive manufacturing is increasing, not only for prototyping and by private individuals, but also as an integral part of industrial processes. But Sweden lags behind.

Additive manufacturing technology has been around since the beginning of the 80s, but it is only in recent years that development has really taken off. So-called desktop printers are now the most common type. They can be bought for a reasonable sum, and an increasing number of private individuals use them in their homes. But additive manufacturing is also becoming more and more frequent in companies. In 2019, the global additive manufacturing market grew to over USD 10.4 billion, the highest figure the industry has achieved in its nearly 40-year history.

The trend is also clear if you look at the number of patent applications involving additive manufacturing:

Number of patent applications within additive manufacturing (AT), 2000–2018. Source: European Patent Office

Filed patent applications, broken down by company. Source: European Patent Office

Sweden is regarded as lagging behind in the development and use of additive manufacturing, but the focus on catching up has increased in recent years. According to a recent survey by research institutes Swerim and RISE, the number of companies working with additive manufacturing in Sweden tripled from 2015 to 2018. Likewise, the number of AM researchers at institutes and universities/colleges has increased significantly, and the survey reveals that many major companies and startups collaborate with academia in the field.

A number of initiatives have been taken in Sweden to increase the use of AM, mainly in metal printing. A national agenda for AM and 3D printing was developed by Vinnova (Sweden’s innovation agency) in 2013. You can find it via this link: A Swedish agenda for research and innovation within additive manufacturing and 3D printing.