What is Additive Manufacturing?
Additive Manufacturing (AM) is an appropriate name to describe the technologies that build 3D objects by adding layer-upon-layer of material, whether the material is plastic, metal, concrete or human tissue.
When Japanese Hideo Kodama in 1981 came up with an idea to realize three-dimensional printing, inspired by a photo-hardening polymer technology, he was too far ahead of his time. It wasn’t until 12 years later, when MIT developed the first powder bed process using inkjet print heads that the term 3D printing began to be used.
Since then, a range of terminology has been introduced to describe the process of using a printer and CAD software to grow objects layer by layer: additive manufacturing, free form fabrication, rapid prototyping, layered manufacturing and direct digital manufacturing, to name a few.
Although most terms can be used interchangeably, there is one exception: While Rapid Prototyping (RP) means to produce a prototype of a new component, Additive Manufacturing (AM) provides opportunities for both prototypes and final components.
This difference is crucial as the first normally means that the component is produced as a copy of something that will be manufactured traditionally, using subtractive manufacturing, while additive manufacturing opens a world of design opportunities without the limitations of subtractive manufacturing.
A variety of materials can be used in additive manufacturing. Polymers and metals are the most common types of material and are particularly efficient for low-volume manufacturing and to minimize waste. Other materials with possibilities are, for example, medical and biochemical materials, glass and even chocolate.
METAL ADDITIVE MANUFACTURING
For metal additive manufacturing, components with complex designs, or those benefitting from being light, such as parts for aircrafts, cars, trucks or medical applications, will find advantages, while components with simple designs, or where weight is not an issue, are better produced using traditional, subtractive manufacturing.
The aerospace and medical industries are particularly well suited to see growth and success from additive manufacturing, although companies in a wide range of industries find value in the additive manufacturing process.
As the business scope for additive manufacturing expands, there’s a growing need for technical standards. To address this need, the International Organization for Standardization (ISO) and ASTM International have jointly created the Additive Manufacturing Standards Development Structure. It aims to coordinate the creation of standards related to materials, processes, equipment and finished-part properties while also supporting specific standards for aerospace, medical devices, automotive and other industries.
THE ADDITIVE MANUFACTURING POWDER
Without the right powder, additive manufacturing wouldn’t work. The quality and properties of the powder strongly influences the properties of the component. Simply put, there are three major aspects to consider: Selection of raw material, particle size and morphology. There are five major alloy groups used in the additive manufacturing processes today; steel, cobalt chrome, nickel, aluminum and titanium. Sandvik offers all these material families – and can even tailor-made the powder according to the customers’ applications or additive manufacturing process.
Depending on the manufacturing method and specification, the melt is transformed into the correct particle size and morphology in a so-called gas atomization process. Depending on what additive manufacturing process the powder is going to be used in, it needs to be sized so the powder particles can be used in the process. As an example, powder bed fusion laser requires very small particle sizes – down to a few microns, while directed energy deposition machines can handle substantially larger particle sizes – around 100 microns. There is a clear trend going forward to develop new alloys and tailored powder for additive manufacturing – to expand the current material program. For Sandvik, with our metallurgical expertise along with a comprehensive competence within R&D, powder atomization and additive manufacturing, this is a natural development.
SUSTAINABILITY IS A DRIVING FORCE
Powder metallurgy is a recognized green technology – and additive manufacturing is also a much more sustainable production technology compared to traditional manufacturing methods, such as machining, since it for example minimizes waste and reduce energy consumption. Components benefitting from being light will also find advantages in additive manufacturing – and weight reduction is a constant key issue for the aerospace industry, driven both by fuel cost and carbon footprint. The same is true for cars and trucks, and everything else that moves.
Apart from reduced fuel consumption, additive manufacturing offer several additional sustainability advantages. Fewer transports and production steps than traditional manufacturing, as well as the fact that it utilizes a lot less material than traditional manufacturing, both thanks to the design that requires less material, and to the actual production.
When printing a component, approximately 95 percent of the powder you put into the process is used; the rest can be recycled in a new melt. Compare that to traditional manufacturing where you start off with a chunk of material and reduce large amounts of chips.
ASTM international’s seven standardized AM technologies
- Powder Bed Fusion: A laser or electron beam is used to fuse the powder, in a powder bed, under protective atmosphere or in vacuum.
- Binder Jetting: A binder is added to the powder bed in the shape of the component to be produced, in the following step the binder is cured and the greenbody sintered to full density.
- VAT Photopolymerisation: Liquid photopolymer in a vat (container) is cured by light-activated polymerization.
- Material Jetting: Building a structure by dropping the material.
- Material Extrusion: The material is dispensed through a nozzle.
- Sheet Lamination: The component is created by bonding sheets of material.
- Directed Energy Deposition: A laser or electron beam melts the powder or wire as it’s deposited on the surface.
The history of Additive Manufacturing
- 1981: The first plastic components produced by 3D printing were made in Japan.
- In 1984, two French inventors filed a patent for the stereolithography process, and the same year Chuck Hull from 3D Systems filed another patent for a slightly different approach that is still used today.
- In 1988, S. Scott Crump of Stratasys invented a plastic extrusion method.
- In 1993, MIT developed the first powder bed process using inkjet print heads. The term 3D-printing began to be used. The same year a dot-on-dot technique was delveloped.
- 1999: The first lab-grown urinary bladder augmentation organ is implanted in a human being.
- The term additive manufacturing started to be used in the first decade of the 2000s.
- The first additive manufacturing machines for metal powder came in 2001.
- Sandvik introduced metal powder for additive manufacturing already in 2002.