Waterproofing 3D prints
3D printing has grown to become an invaluable engineering tool in recent years. The technology finds applications in rapid prototyping and low-volume manufacturing of a wide range of parts. The traditional machining methods are slow and costly by comparison, which is restrictive to student clubs such as our own.
The Palouse RoboSub mechanical engineering team regularly utilizes 3D printing. For low-load bearing parts both within and external to our pressure vessels, 3D prints can even become permanent additions to our vehicles. Our current and upcoming AUV’s utilize 3D-printed brackets for mounting cameras, thrusters and hydrophones. Within pressure vessels, 3D-printed parts are responsible for securing many electrical components.
A notable limitation to 3D-printed components, however, is the inability to produce reliably watertight parts. 3D-printed exterior brackets allow flooding through microscopic surface holes, and water will fill the low-density support structures within the part. This makes 3D-printing entirely unsuitable for walls of pressure vessels or positive buoyancy applications. With carefully tuned printing settings a watertight printed surface may be produced, but this is both unreliable and prone to failure with regular wear-and-tear.
In Fall 2019 a group of Palouse RoboSub members began exploring additive manufacturing methods to make 3D-printing more viable in the underwater environment. Our approach was to shield printed PLA components with a thin nickel surface through electroplating. Our student engineers researched and produced a Watts bath electroplating tank and devised a method for reliably plating non-conductive 3D-prints. The process is inexpensive, takes as little as a few hours to complete, and the materials are largely reusable.The results yielded small-scale watertight containers to at least fifteen feet of depth, as well as far more durable 3D-printed structures. Parts produced this way are very similar to fully metallic alternatives at a fraction of the cost, production time, and weight. The project has been on hold as of March 2020 due to facility closures, but we are eager to continue our research and incorporate this manufacturing method into our vehicles.
Nickel-electroplated 3D printed vessels, watertight with O-ring seals