What is Additive Manufacturing?
There are in fact a number of different subtypes of additive manufacturing including 3D printing, but also rapid prototyping and direct digital manufacturing (DDM). Recent advances in this technology have seen its use become far more widespread and it offers exciting possibilities for future development.
An example of a 3D printed ceramic pot using additive manufacturing
How Does it Work & Processes Involved?
The clue to the basics of additive manufacturing; rather than producing an end result by taking material away, it adds to it instead.
Traditional manufacturing methods involve a material being carved or shaped into the desired product by parts of it being removed in a variety of ways. Additive manufacturing is the pole opposite; structures are made by the addition of thousands of minuscule layers which combine to create the product. The process involves the use of a computer and special CAD software which can relay messages to the printer so it “prints” in the desired shape.
Suitable for use with a range of different materials, the cartridge is loaded with the relevant substance and this is “printed” into the shape, one wafer-thin layer at a time. These layers are repeatedly printed on top of each other, being fused together during the process until the shape is complete.
The Benefits Conventional manufacturing techniques are capable of producing a great range of shapes and designs but additive manufacturing takes production to the next level.
One of the greatest benefits of this more modern technology is the greater range of shapes which can be produced. Designs that can’t be manufactured in one entire piece with traditional means can easily be achieved. For example, shapes with a scooped out or hollow centre can be produced as a single piece, without the need to weld or attach individual components together. This has the advantage of being stronger; no weak spots which can be compromised or stressed.
The additive manufacturing process is very quick too, rather than needing an endless round of meetings from engineers in order to be able to tweak designs. With the assistance of the CAD software, making any changes takes simply the click of the mouse. Rapid prototyping in particular is very quick, with full models produced quite literally overnight in some cases. This provides companies with far more flexibility, and also has the result of slashing costs too.
In the past, the limitations of production have all too often influenced design, ruling out ideas because they weren’t practically achievable. The introduction of this technology and its development means the process has been spun on its head, with design now driving the production.
Additive Manufacturing Definition, Technologies & Terms Used
If you’re not familiar with the terms used within the industry, it can seem confusing with seemingly similar processes using different terms.
3D printing is a phrase coined by the media and is often used to refer to all types of additive manufacturing. However, strictly speaking 3D printing is defined as “…fabrication of objects through the deposition of a material using a print head, nozzle or other printer technology”. This differs slightly from additive manufacturing which was defined by the industry as “…… making objects from 3D data, usually layer upon layer…”. In practice the phrases 3D printing and additive manufacturing may be used interchangeably by some sources so it’s important to understand the process which is actually being discussed.
Rapid prototyping is another phrase often bandied around, but is increasingly being replaced by additive manufacturing. This is because the use of the word “prototype” can be misleading. As well as creating a test design, rapid prototyping can also create functional components, plus moulds. Different materials are compatible with additive manufacturing and the process which is used is in part determined by what’s being used.
Selective Laser Sintering (SLS)
Selective Laser Sintering (SLS) , Direct Metal Laser Sintering (DMLS) and Selective Laser Melting (SLM) are three of the most common techniques.
Diagram of the selective laser sintering process
SLS and DMLS are effectively the same process, merging the particles in the material, without achieving a full melt. SLS is used to describe the sintering process when applied to non-metal materials, with DMLS used for metal.
SLM is slightly different because it involves a full melt with the metal heated and then cooled to fully consolidate. Although very similar, this full melting process means that the results won’t be porous, unlike with DMLS.