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Additive manufacturing is one of the most exciting technologies to be unveiled in recent years, with the possibilities for both consumers and in industry almost limitless.
At the very core of this is the 3D printing machines, with the technology ranging from basic consumer designs to those being used in heavy industry. There’s no such thing as a single additive manufacturing machine because there’s such a great range of classifications, with diversity in areas such as the materials processed, the energy source or binder used, and the type of feedstock. Different types of machines work in different ways and have varying degrees of capability.
Whether you’re a business considering investing or a home user thinking about buying a 3D printer, it’s essential to understand the constraints of the additive manufacturing machine you are buying, and the results it will produce.
To do this you’ll have to consider a number of key factors.
Firstly, although Additive Manufacturing is able to work with a wide variety of raw materials, not every machine will work with every substance. Metal for example is typically beyond the parameters of what’s available on a domestic 3D printer because of the size, cost and components.
The machines may create items made from plastics, waxes, metals or other less common materials such as ceramics and glass, but the processes involved can be very different.
The way the material is joined together to create a solid structure, also known as the energy source, will be in part determined by the types of materials being used. This also ties in to the feedstock, which can be liquid, sheet, powder or wire. A high quality energy source may use lasers, following a process known as sintering to create a solid and robust model either from plastics or metals.
Alternatively, heated nozzles may be used to print out plastics which rapidly cool, setting firm. In other machines, there’s a two part process where a binder and the raw powder are laid out separately and then combined, creating a strong layer that adheres together.
For metals either sintering or a full melting process needs to be followed to create a new compound which follows the design shape. Depending on the geometry of the structure being created, and the materials being used, soluble supports may also be printed and used, later being discarded when the final product is ready.
Additive Manufacturing machines which are based on a powder bed system use a reservoir, and a coating mechanism which spreads out the powder onto a plate. Each of the slices laid down are ultrafine, often being just a fraction of a millimetre, although the actual thickness can be adjusted.
Once the powder is spread out, it can either be bound together or alternatively, heated with the use of a laser energy beam. In particularly advanced machines, different lasers can be used offering varying levels of power. These types of systems are known collectively as laser melting processes, even though in reality a full melt is not achieved.
Processes such as sintering and melting are part of these types of Additive Manufacturing machines, where each layer is solidified bit by bit, until the final design is complete. The type of metal being used will determine the right process, with alloys performing far better in response to sintering than to full melting, due to the variation in the temperature of the melting point.
Electron beam melting
Another variation on the Additive Manufacturing machine system is those which are powder fed, the main difference being the way in which each layer is added.
Powder is still added to the cross section but as it flows through the nozzle, a laser heats the surface, a method which is incredibly precise. Known as Laser Metal Deposition, Laser Cladding and Directed Energy Deposition, the lasers are a critical part of these machines. Thicknesses between 0.1mm and several centimetres can be achieved through this method.
A new technology which has been developed for use is LENS: Laser Engineered Net Shaping.This new method isn’t for the sole creation of new parts and components, but for the repair of existing pieces, making it far quicker, cheaper and easier. LENS adds materials to existing products, repairing damaged surfaces which would be expensive to totally replace, such as chipped turbine blades.
Many companies around the world have taken these technologies and have looked to fuse them with existing designs.
In Japan, cutting edge company Masuura created a truly hybrid design that mixed powder bed fusion technology with CNC milling.
The Höganäs Digital Metal process is another fusion creation, allowing the item to be printed at room temperature without any of the melting which can often occur.
Under the spotlight right now, there’s likely to be a number of hybrid designs that look to mingle Additive Manufacturing technology with existing abilities.
We always enjoy speaking about any aspect of additive manufacturing, give us a call to discuss your requirements or questions on +44 (0)1489 797 696. Alternatively complete the online form and we will contact you directly.
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