With A Little Heat, Printed Parts Handle Vacuum Duty

We don’t have to tell the average Hackaday reader that desktop 3D printing has been transformative for our community, but what might not be as obvious is the impact the technology has had on the scientific community. As explained in Thermal Post-Processing of 3D Printed Polypropylene Parts for
Vacuum Systems
by [Pierce Mayville], [Aliaksei Petsiuk], and [Joshua Pearce], the use of printed plastic parts, especially when based on open source designs, can lead to huge cost reductions in the production of scientific hardware.

More specifically, the authors wanted to examine the use of 3D printing components to be used in a vacuum. Parts produced with filament-based printers tend to be porous, and as such, are not suitable for fittings or adapters which need to be pumped down to below one atmosphere. The paper goes on to explain that there are coatings that can be used to seal the printed parts, but that they can outgas at negative pressures.

The solution proposed by the team is exceptionally simple: after printing their desired parts in polypropylene on a Lulzbot Taz 6, they simply hit them with a standard consumer heat gun. With the temperature set at ~400 °C, it took a little under a minute for the surface of take on a glossy appearance — the result reminds us of an ABS print smoothed with acetone vapor.

As the part is heated, the surface texture visibly changes. The smoothed parts performed far better in vacuum testing.

In addition to the heat treatment, the team also experimented with increasing degrees of infill overlap in the slicer settings. The end result is that parts printed with a high overlap and then heat treated were able to reliably handle pressures as low as 0.4 mTorr. While the paper admits that manually cooking your printed parts with a heat gun isn’t exactly the ideal solution for producing vacuum-capable components, it’s certainly a promising start and deserves further study.

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