3D Printing Plant for Human-Rated Spacecraft

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Animations by Ralph Zoontjens, www.id-z.oneMy proposal for the additive manufacturing plant includes:• 3D ablative paste extruder, build volume over 5m diameter, 8m tall, and more if expanded• Integrated machining toolhead• Liquid metal 3D printer, build volume up to 5m diameter, 8m tall, more if expanded• Workshop/FabLab creation of parts and subassemblies• Paint shop• Assembly station for marriage of elements• Largely automated plant logistics and maintenance• Tent construction with solar roof (with almost 200m diameter visible from space) and smaller subunits inside allowing specific control of environmental parametersThe 3D printing stations work as follows. Since parts are mainly circular in shape, a rotating print bed is an optimal solution. With only two worm rod driven linear motor arms great precision is achieved giving rise to a relatively low-cost, expandable, versatile and easy to program system. When a piece has completed printing, the rotating table lowers, thereby setting the finished product onto a conveyor belt to be transported to the assembly station where it is installed into the spacecraft.The dedicated heat shield fabricator unit houses two arms integrating CNC post-machining in a single production unit. Ablative paste is stored in a mixing tank and fed into the worm-driven hopper on the 3D printing tool head. After every few ½ inch thick layers, the head goes into park mode for a refill allowing the resin to harden in the meantime, all without requiring complex piping solutions.The metal 3D printing unit incorporates NASA’s Electron Beam FreeForm Fabrication (EBF3) technology. This allows for the manufacture of complex geometries that require little post-machining. A wire-fed extrudate allows for large scale parts and high variety of materials. Aluminum 2219 and titanium 6-4 alloys for example have been tested as having equivalent mechanical strength as deposited to traditionally wrought annealed counterparts. Electron beam melting is precise and low in power consumption, while being suitable for microgravity and vacuum conditions. One robotic machining station is needed for finishing of the metal fabricate, in this station installed on a second rotating table, before being transported further on through the assembly line.This project greatly aided me in improving my 3D animation and rendering skills, as well as in developing technical know-how related to human-rated spacecraft design and 3D printing. Thanks to NASA Lyndon B. Johnson Space Center for initiating this project.