A joint development programme between Linde and 3D Medlab, now part of Marle Group, has announced the results of the testing of its new process gas for the optimisation of the additive manufacturing of medical components made from Ti64, a titanium alloy.

Testing of the process gas took place between January 2020 and March 2021, with the aim being to investigate the effect of the new process gas on spatter formation and process stability during laser powder bed fusion (L-PBF) of Ti64 lattice structures and their resulting properties.

L-PBF is an advanced additive manufacturing process which allows for the production of complex, latticed structures such as intricate medical implants.

The method employs a laser as a heat source to selectively melt consecutive layers of metal powder to consolidate the material and product a part.

It was discovered that spatter emission was reduced by 35% when using argon-helium mixtures as opposed to argon alone.

When a process gas has a lower spatter emission percentage, the risk of manufactured defective parts is considerably reduced and the overall surface quality improved.

Speaking about the advantages of the discovery, Sophie Dubiez-Le Goff, Expert Powder Metallurgy for Additive Manufacturing at Linde, said, “The ability to print reliably repeatable products is key to improving product qualification, which is crucical for the medical industry.”

“Additionally, from a commercial perspective, printing time is the greatest single cost element in additive manufacturing, but this can be sped up for thin parts by using just the right atmospheric gas mixture. Linde’s novel argon-helium mix has been developed to do just that and is a major step forward in the manufacture of titanium medical devices.”

When creating medical devices with highly intricate parts, the finished product must be as close to the original design specification as possible. Two fundamental factors include the levels of porosity and surface quality, as it’s important to minimise the amount of metal powder parts that can potentially be released into the human body.

“Porosity is the first criteria we look at in terms of defining the quality of an additive manufactured medical device.”, said Gael Volpi, Head of Additive Manufacturing, Marle Group.

The study was aimed at assessing the ideal gas mixture to optimise both the quality and production speed.

A mixture proved to be far more useful as, when using argon alone it was shown that there was a significant amount of spatter – or molten metal particles – splashing against other parts being printed.

Dubiez-Le Goff also said, “Higher productivity was not reached at the expense of quality.”