Engineers have developed a new type of additive manufacturing that toughens printed parts over time, giving them a 4D aspect.

(Image: Loughborough University)

Dubbed MaTrEx-AM (Material Treatment Extrusion Additive Manufacturing), the technique from Loughborough University uses acetone to add durability to targeted layers of the deposited material. According to the Loughborough team, varying how much acetone is applied and where it is used allows manufacturers to create items with novel mechanical properties, such as controlling how parts deform.

“The process adds material layer-by-layer – there are grooves between the layers, a bit like you’d see if you stacked lot of logs sideways on top of one another, all lined up,” said Dr Andy Gleadall, a senior lecturer in additive manufacturing at Loughborough. “3D printed parts are often weak because of the way layers are laid down in sequence, so there are geometric defects between the layers and the bonding of material between layers may not be as good as the pure polymer.”

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Real-world applications for the new AM technique include biomedical implants, as well as 4D lattices for helmet padding that could help minimise head injuries in contact sports or in defence and security settings. The research paper, MaTrEx-AM: a new hybrid additive manufacturing process to selectively control mechanical properties, was published in Additive Manufacturing.

“The new capabilities are potentially valuable for a huge range of parts and structures, but perhaps most obvious ones would be parts that deform during operation and the way in which they deform needs to be controlled,” said Dr Gleadall.

“The time-dependent nature of mechanical properties means the approach adds a new dimension to material capabilities, with in-situ hybrid processing facilitating a true 4D printing process.”