Additive manufacturing processes for various applications

3D printers are becoming increasingly popular in industry and for home use. Many components can be manufactured here using various additive manufacturing processes with different materials.

The term "additive manufacturing process" refers to the type of manufacturing: During manufacturing, the materials are assembled in layers to form the intended component. All you need is the right 3D printer and the associated 3D design data for the component.

We will explain to you which additive manufacturing processes are currently available and where their strengths and weaknesses lie.

Additive manufacturing of components and structures

Additive manufacturing processes stand out from other common processes because they have many advantages over them:

• the subtractive manufacturing process is often used to mill or cut shapes out of a material. However, these methods cannot be used successfully for particularly small or delicate components or for components with cavities.
• The so-called formative processes , which are used for cast parts, can also handle such filigree components or parts with cavities. However, the process is very complex and often not very clean, which leads to optical and technical errors and thus to rejects and losses.

3D printing in additive manufacturing can score here because it can handle any shape and can also be used with many different materials. In the additive manufacturing process, the material is built up layer by layer – and very precisely. Due to the different additive manufacturing processes, not only all shapes , but above all metal parts as well as products made of paper, sandstone or ceramics .

Additive manufacturing processes or subtractive manufacturing processes?

Despite all the advantages of additive manufacturing processes, the subtractive processes cannot yet be replaced, as they also have a number of advantages. Which process is ultimately used is therefore always determined by the type of product, the production volume and the available production time.

For example, subtractive manufacturing processes are suitable for mass production that needs to be completed very quickly. The components can be processed very cleanly and precisely, especially when milling, turning or drilling, even with particularly fine bores. Unfortunately, the process also has many disadvantages compared to the additive manufacturing process: for example, the loss of material is very high, tools wear out all the time and the programming of the more expensive machines is somewhat more complicated and time-consuming.

Additive manufacturing processes advantages and disadvantages

All common additive manufacturing processes have some advantages and only a few disadvantages compared to the subtractive process:

Advantages of additive manufacturing processes:

• Simple handling and easy programming
• Complex workpieces and hollow shapes can also be manufactured
• Many materials can be used (plastics, metals, paper...)
• Thanks to the layered structure, the production process consists of just one step
• No tools are required, therefore no wear and tear
• There is little loss of material
• Internal filling structures mean that components do not have to be made entirely of solid material, which enables weight savings.

Disadvantages of additive manufacturing processes:

Unfortunately, there are also a few disadvantages here, depending on the material with which the product is to be manufactured:

• Production is slower
• In the case of larger overhangs, support structures are required for the layered structure
• Some materials are not thermally resilient
• Rough surfaces are created which may have to be reworked
• The manufacturing material is slightly more expensive

Additive manufacturing plastic - advantages and disadvantages

Many additive manufacturing processes that were originally designed for 3D printing from plastic can also be used to manufacture metal parts thanks to state-of-the-art technology. The most well-known method (FDM/FFF) is therefore presented separately in the next section.

Examples of additive manufacturing processes that are suitable for plastics include:

• Stereolithography (SLA). Photopolymers are used here. The production is very precise, results in a smooth surface and therefore requires only little post-processing. However, the parts are not particularly robust and not lightfast.
• Selective Laser Sintering (SLS). The material used here is polyamide or nylon in powder form. Although the selection of materials is small, the accuracy during processing is good and the components are also very strong. However, the process requires a high level of energy and is complex on the part of the machines.
• Multi Jet Fusion (MJF). Plastic powder is also used here and no supporting structures are necessary. This allows very complex components to be manufactured. The resolution and accuracy are very good and the products are stable. Most importantly, the process is very quick. Disadvantages are the somewhat rough surface and the creation of only one-color products.

Additive manufacturing metal using FDM / FFF

The additive manufacturing process FDM or FFF particularly interesting for industry. This is “Fused Deposition Modeling” (FDM) or “Fused Filament Fabrication” (FFF). It was originally developed to build up a plastic layers. Therefore, it is also popular for the private sector.

Today, however, it is possible to use metal powder for the 3D printing of metal products . However, after production, the resulting product still has to be debound and sintered in order to achieve the desired metal structure. Post-processing is also necessary because of the rough surface.

Here, too, the production speed is unfortunately a bit slow, but with new print head technologies such as the 4Move from Multec, multicolored or multi-component products are possible - which, however, plays a subordinate role with metals. The big advantage here is the cost-effective production of very stable and resistant components.