What is additive manufacturing?

Many people may simply refer to additive manufacturing as ‘3D Printing’ or may band the term ‘rapid prototyping’ when trying to define it. However, both are processes that are subsets of additive manufacturing.

Additive manufacturing (AM) in fact encompasses many technologies in addition to 3D printing and Rapid Prototyping (RP) such as, Direct Digital Manufacturing (DDM), layered manufacturing and additive fabrication.

AM can be used to describe the numerous technologies that are used to create 3D objects by adding layer-upon-layer of material. Additive manufacturing builds geometries by “adding” whereas subtractive manufacturing is the name of the process where parts are created by removing material.

Whether the material is plastic, ceramics, metal, concrete, or as the technology is developing on a weekly basis, by the time you read this article, we could be seeing human tissue and other everyday objects being used in additive manufacturing.

The limits for using additive manufacturing are endless. In the early days of using AM, the focus was on producing prototypes as quickly as possible. However, although rapid prototyping is still an important factor for the use of AM. More recently, it is being used to fabricate end-use products in numerous industries.

Again, the opportunities are endless, at Photocentric our printers are being used to produce parts in aircraft, automobiles, dental surgeries, medical implants, filmsets, fashion products, farming machinery, jewellery, sportwear, eyewear, and many more sectors.

Since the turn of the century, most industries have enjoyed a digital revolution. Now, AM can bring digital flexibility and efficiency to manufacturing operations for most businesses.

So, what is additive manufacturing? In simple terms, additive manufacturing is the future.

How does additive manufacturing work?

As discussed, additive manufacturing references technologies that develop three-dimensional objects one layer at a time. Each successive layer bonds to the preceding layer of material.

However, the process begins with the creation of the required object. Objects are digitally defined by 3D printing software. Computer-aided-design (CAD) files are converted to .stl files that show the object sliced layer by layer.

Once a CAD sketch is produced, the AM equipment reads in data from the CAD file and lays downs or adds successive layers of liquid, powder, sheet material or other, in a layer-upon-layer fashion to fabricate a 3D object. Different 3D printers will work in different ways. Material is either deposited, melted, or cured to fuse the final part.

Examples of Additive Manufacturing (AM)

SLA

Stereolithography (SLA), invented in the 1980s, was the world’s first 3D printing technology. This format requires the utilisation of laser technology to cure layer-upon-layer of photopolymer resin (polymer that changes properties when exposed to light). The build occurs in a VAT or pool of resin when a laser beam is directed into it and cures the resin. During the build cycle, the platform is continuously repositioned, lowering by a single layer thickness each time. The process repeats until the build or model is completed.

LCD

LCD additive manufacturing works in a very similar way to SLA. However, instead of the requirement for a laser, an LCD screen is used as a light source to ensure a quicker process. With this format entire layers are encoded simultaneously, rather than small area by area. LCD printing benefits from one of the greatest technological advances of the last 50 years, with the use of visual display screens. It can produce much larger volumes than alternative methods, creating new products at rates previously unimaginable. The simplicity of the process is its strength, if using daylight as opposed to UV, the exposure is even and the machine stable for many years of use.

FDM

Along with SLA , the Fused Deposit Modelling (FDM) process involves the use of thermoplastic materials injected via nozzles onto a platform. The materials are polymers that change to a liquid upon the application of heat and solidifies to a solid when cooled, prior to the application of the next layer. The process continues to repeat until the build or model is completed.

MJM

Multi-Jet Modelling (MJM) is a similar additive manufacturing process to how a regular inkjet printer would work, in the way that a head travels along dimensions-x, y, z as required, applying layers of thermopolymer material, layer-by-layer.

Although a very accurate process, MJM models are usually not suitable for functional prototypes as materials used are slightly more brittle and are not UV-resistant. There are also restrictions in the geometric freedom and high material costs compared to other 3D printing processes.

3DP

3DP Binder Jetting is an additive manufacturing process involves building a model in a container where a liquid binding agent is selectively deposited to join powder particles of either starch or plaster. Layers of material are then bonded to form an object. The printhead strategically drops binder into the powder. The job box drops, and another layer of powder is then spread and binder is added. Gradually, the part develops through the layering of powder and binder.

SLS

Similar in ways again to SLA technology, Selective Laser Sintering (SLS) utilizes a high-powered laser to fuse small particles of plastic, metal, ceramic or glass together. During the build cycle, the platform lowers layer by layer. The process repeats until the build or model is completed. However, unlike SLA technology, support material is not needed as the build is supported by unsintered material.

Other

Although there are other various 3D printing technologies, they are not worth discussing in the use of additive manufacturing.

Advantages of additive manufacturing

Time saving

Although it is not all about prototyping, additive manufacturing is ideal for getting prototypes made quickly. As discussed, the process enables parts to be manufactured directly from a 3D CAD file, which eliminates the cost and lengthy process of having fixtures or dies created.

Design flexibility

As the manufacturing process is so quick, changes to designs can be worked on continuously, enabling the part to be enhanced throughout without drastic delays and increased costs for tooling updates.

Complex geometries

Additive manufacturing enables engineers to experiment with new ideas, designing parts that are free from previous machining restraints, incorporating complexities that are not possible using other methods. Intricate features can now be incorporated directly into the design phase. Parts that previously required assembly and welding of multiple pieces can now be built as a single part, which makes for greater strength and durability.

Weight reductions

Designers can reduce the requirement for additional weighty parts, while maintaining the part’s strength and integrity, by incorporating structures into the design phase, eliminating the need for surplus materials and components.

Environmental

Additive manufacturing is seen as a much more carbon friendly process than others, less waste is produced than subtractive manufacturing.

At Photocentric we invented LCD 3D printing, which is already the lowest carbon form of 3D printing. We are now developing the next range of screens using monochrome displays that let three times the amount of light through as colour ones. By using centrifuging instead of washing and selective area illumination in an autonomous process we can deliver even lower carbon footprint manufacturing methods.

Money saving

When all is said and done, the other benefits pale into insignificance if the process costs more to the manufacturer. However, additive manufacturing reduces the cost for industries in many ways. No more so than the astronomic cost of tooling, dies and fixture production.

With the additional increase in logistical costs, being able to print your own parts on site has enabled customers to save thousands on shipping in parts from far of destinations.

Further reading

What is
3D Printing?

How to overcome bending and warping when 3D Printing large models

Choosing the correct 3D software
for your needs