Dec 2, 2014

MetalicaRap DIY electron beam welding and vapor deposition 3d printer

MetalicaRap is an open source DIY 3D metal  home solar cell printer, based on the principles of electron beam welding and vapor deposition. MetalicaRap is currently in the early design and development phase.
The goal is to have affordable home-manufacturing of solar cells, key electrical parts and milled-quality metal parts. MetalicaRap has a very ambitious mission to bring down a price of home solar power system from 10.000 euro to 400-500 euro range by printing it.
If this projects is successfully developed it could make a major revolution in DIY 3d printing, solar power and DIY electronics.
This project is too big and complex to cover in this post, I'll follow it and update it but be sure to check the project homepage for much more information.


MetalicaRap

Proposed technical characteristics:
  • A build volume of about 30cm x 30cm x30cm (prototype will be 24cmx24cmx24cm as this is min that can still print babies)
  • Produces finished parts +/- 20 µm over 20mm
  • Finished parts should be the metallurgical equivalent to wrought iron milled metal parts(full strength, >98% density)
  • The printer is largely self reproducing(i.e. it can print many of its own parts)
  • Single Phase electrical supply
  • Minimum consumables beyond metal powder (avoiding need for e.g. argon gas would be an advantage for later designs)
  • Cost for parts which it cannot itself print plus the raw material for printable parts is less than the cost of a used car (self replication plus self build kit may reduce the price by approximately 100 times i.e. from the existing price of a metal 3D printer or solar cell plant; 1,000,000 euro price tag,to 10,000 euro self print/kit price. historically the plastic printer went from 30,000 euro commercial price to 500 euro in 2009 via this approach)
  • The build-rate can be slow i.e. 0.2 kg per hour.
  • Max height should be 2.4m so it can fit in a home. ( first/simpler to construct prototype will be taller than this until we know how much we can bend beam while maintaining spot size, the bigger the bend the shorter it will become)
  • Shape and size of vacuum chamber and electron gun power rating should be suitable for Solar Cell Printing(300W).

Since it is a high tech advanced design with many sophisticated technologies integrated in single device, here are some advantages and disadvantages:

Advantages of current chosen design approach
  • Fully functional parts directly from standard metals
  • For most parts it may offer dimensionally finished metal parts IT grade 7
  • Good metallurgy on all common metals (Melting process rather than sintering process ensures near 100% of solid material)
  • Closed loop system
  • Self measurement of finished part tolerances.
  • May offer automatic self correction (subtractive machining steps during build process and feedback with compensation used in the additive process).
  • Eventual additional Benefits;
  • Can print thin film CIGS Solar cells in existing 10−4vacuum chamber with existing electron gun. Will be able to self print additional required parts for solar cell printer.
  • Can create its own metal powder from scrap metal.
  • Can finish the refining process for titanium metal by melting titanium sponge, which may lead to a 25 fold reduction in the titanium price.
Disadvantages of current chosen design approach
  • Vacuum chamber needs on going maintenance.
  • Given the quantity and quality of metal/materials used in 10-4 torr vacuum chamber construction they may have high cost or be hard to obtain. (Limited outgasing required)
  • Difficultly in managing metal powders, indicated by the need to have layer error correction, Problem area's including; powder layer flatness, metal meniscus blob formation, metal powder trapped in work piece (i.e. designed internal closed cavities, designed internal porous or honeycomb structures most likely impossible without additional processing or work on the part after printing).
  • Quality Control may be a hurdle to overcome - on the fly heat treatment process development (to overcome residual stress present in the first few layers) may be desirable but optional. Layer by layer temperature measurement is one way for metallurgical quality assurance. Currently multiple printed and tested tensile test samples are used to prove most processes. This is a problem in general for additive manufacturing of all sorts at present.
  • Adequate surface finish may require post processing, depending on the purpose of the part.Later by the addition of argon we could do electronbeam polishing.
  • Non-desktop size wardrobe size,chamber volume approx 0.3m cubed.

MetalicaRap homepage on RepRapWiki, it has very detailed and extensive information and technical drawings of the project:

http://reprap.org/wiki/MetalicaRap

there is a project forum: http://forums.reprap.org/list.php?215%7Cthe

Here is a video that demonstrates the electron beam evaporation and deposition process: