Sweden 3D prints the world's first composite diamond

A Swedish engineering group has 3D printed the world's first composite diamond.

Sandvik, a Stockholm-based engineering group specialising in tooling, materials technology, mining and construction, unveiled its composite diamond to journalists at the Digital Difference in Manufacturing convention in Sandviken, Sweden, earlier in May. The event was co-hosted by Microsoft and Sandvik.

Sandvik has been working on 3D-printing increasingly hard materials, including its "unsmashable" titanium 3D printed guitar.

If you're thinking about printing yourself some bling for your ring, though, hold the phone. The diamond is intended for industrial use.

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"While this diamond does not sparkle, it is perfect for a wide range of industrial uses.

"The new process means that this super-hard material can now be 3D printed in highly complex shapes and can thereby revolutionise the way industry uses the hardest natural material on the planet," Sandvik said.

Diamond is roughly 58 times harder than any other material in nature. It has a wide range of industrial uses.

Since 1953 it has been possible to produce synthetic diamond, but since it is hard and complicated to produce by machine - it is almost impossible to form complex shapes, Sandvik noted.

3D printing – thanks to the additive manufacturing process – will make it easier to make complex shapes. Additive manufacturing involves creating an item by adding layer by layer, while subtractive manufacturing involves shaping by cutting away.

"By using additive manufacturing and a tailor-made, proprietary post-processing method, Sandvik has managed to 3D-print diamond composites which can be formed into almost any shape," the company explained.

"The difference between Sandvik’s diamond and natural or synthetic diamond is that Sandvik’s is a composite material. Most of the material is diamond, but to make it printable and dense it needs to be cemented in a very hard matrix material, keeping the most important physical properties of pure diamond."

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The composite diamond is made using a slurry of diamond powder and polymer, using a method called stereolithography, says Sandvik VP and head of R&D and Operations, Mikael Schuisky. Complex parts are produced, layer by layer, using ultraviolet light.

Excess printing slurry can be reused to reduce waste and the diamond powder can also be extracted from the slurry and then recycled.

The step after the 3D-printing is, according to Schuisky, "more demanding" and "extremely complicated".

"This is where Sandvik has developed, a tailor-made, proprietary post processing method making it possible to achieve the exact properties of the super-hard diamond composite." 

Schuisky said the fact that the composite diamonds could now be created in the shapes they were needed - without requiring further machining - opened up the possibility of use in applications previously thought impossible.

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Anders Ohlsson, Delivery Manager at Sandvik Additive Manufacturing, said the composite diamond raised fresh questions about what was possible in future. "On seeing its potential, we began to wonder what else would be possible from 3D-printing complex shapes in a material that is three times stiffer than steel, with heat conductivity higher than copper, the thermal expansion close to Invar – and with a density close to aluminium.

"These benefits make us believe that you will see this diamond composite in new advanced industrial applications ranging from wear parts to space programs, in just a few years from now."