More progresses in additive manufacturing

Pure titanium dental crown and mandibular base plate fabricated by LSF. Credit: Huang Weidong and Lin Xin, Northwestern Polytechnical University, Xi'an

ORNL researchers have demonstrated the ability to precisely control the structure and properties of 3-D printed metal parts during formation. The electron backscatter diffraction image shows variations in crystallographic orientation in a nickel-based component, achieved by controlling the 3-D printing process at the microscale. Credit: ORNL

Since the very beginning of human history, manufacturing has led the way to the production of wealth (even agriculture has been leveraging on manufacturing progress). Indeed progresses have been enormous but if you look closely the paradigm has remained the same: shaping something large into something smaller with a suitable format and characteristics and assembling various parts together to manufacture the final product.

In these last few years, however, a novel manufacturing paradigm is emerging: additive manufacturing. It is progressing both in the realm of nanotechnologies and at normal scales with 3D printers (there are even 3D printing machines that can work in the field to "print" a house).

So far additive manufacturing has been based on small beads of several kind of materials that are sprayed and glued together (or using a material, normally plastic, that can be liquefied and sprayed, solidifying in a few moments). The problem with this technique is that the resulting material is as strong as the glueing makes it. In case of metals the object strength is way lower than the one of the same object obtained through casting or forging. 

Now researchers from the Northwestern Polytechnical University at Xi'an, China, have perfected a technique based on laser to manufacture metal objects. They use laser cladding with synchronous feeding of metal powers resulting in metallic material that has very similar properties to ones obtained through forging or casting.

The advantage of additive manufacturing is that it makes possibile to create objects that would not be feasible as a single piece of material but would need to be constructed by assembling separate parts. This reduces cost (no assembling) and increases structural resistance.

As shown in the photo it is also becoming possible to produce on the spot specific objects, like a dental crown, by having a 3D scanner taking the image of a tooth and a computer preparing the model of the object (the crown) that is then 3D printed.

Another similar, although using a different technology, approach to creating better metallic object through additive manufacturing has been invented at the Oak Ridge National Laboratories.

In this case the researchers are using an Electron Beam Melting System (EBM) to fuse together layers of metal powder with a today unmatched precision. This allows the creation of objects that can be designed in terms of strength, elasticity and robustness at micro level, something that is impossible through forging or casting. A designer can even specify the orientation of a metal crystal in a specific location to obtain a desired characteristics. In turns, this would result in lighter objects, like cars and planes with direct impact on the energy requirements.

Addictive manufacturing will not replace current manufacturing processes but it will flank them starting with niches that will progressively expand. In the next decade I would expect to see this to become an important component of Industry 4.0.

Author - Roberto Saracco

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