3 D printing relies on a heated medium that is gravity fed to the moveable platen. In zero gravity the medium would precipitate out of the heating chamber forming a ball which would only grow larger or break off and float away. This would remain a hazard until it cooled enough to not stick to personnel or equipment.
The solution to zero gravity printing is a complete redesign of current technology.
The printing medium would be in a continuous thin sheet form. Print medium could be made of plastic or metal. The heat source would be a laser that would bring localized areas of the sheet medium up to melting temperature and fuse it to the previous layer.
The printing medium is a continuous sheet the width of the printing platen. Print Medium manufactured as a thin foil in a sheet the width of the platen long enough to roll on the dispensing spool.
Print medium made from plastic or metal could be in the form of micro-beads adhered to a sheet or just a thin layer of either material.
Two spools Spool 1 is the supply spool; it will have a replaceable roll of the printing medium.
Spool 2 is the take up spool.
Platen The platen will be fixed in the X Y direction but movable in the + - Z direction.
Laser Laser is movable in the X Y direction and capable to reach temperatures that would melt and fuse print medium. Laser heat range could be controlled by power, speed or combination of both to either accomodate the fusing temperature of the print medium.
X Y Z controller
Computer to run code
Motors to drive print medium spools laser and platen.
Platen prep sheets Would be manufactured from a material that has a heat resistant core to protect the side that secures to the platen. The layer would be a material that will bond to either metal or plastic print medium. Platen attachment would be hook and loop material or a contact cement. Hook and loop would be a problem for disposal but could be made so the prep sheet can be re surfaced.
Process 1: Platen is coated with a dissolvable medium that will adhere the first print layer.
2: The program is loaded into memory.
3: Program activated
4: Platen lifts, stretching print medium tight against platen sheet.
5: First layer code runs directing laser to run in XY direction melting print medium onto platen sheet.
6: Laser head returns to home position.
7: Platen lowers lifting print medium and detaching it from the first print layer.
7A: Alternate method for metal print medium. Platen lowers creating tension on the printed layer, laser offsets to edge of printed layer and does a second pass freeing up the first print layer.
8: Take up spool pulls print medium a specific distance determined by the size of the printed length.
9; Platen lifts to contact print medium to previous layer.
10: Next layer code is run.
11: Repeat steps 6 to 10 until end of program.
12: At end of program part is removed, first layer adhesive is dissolved, platen is cleaned and prepped for next part.
When the print medium spool is near depletion a sensor will stop the program after the print run and a new roll can be inserted. Program under user control to restart and complete the part design.
Spent print medium rolls could be placed in a machine that would recycle it into a new role thereby reducing waste.
James Madden 2361 Rosewood Dr. San Bruno, Ca. 94066 650-589-8081 Member of TechShop Virtual participant in the Nasa Challenge through San Francisco Portal.