MetalicaRap
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Release status: Experimental
Description | Electron beam sintering tool head (EBS) and high vacuum chamber.(early development phase).
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Contents
MetalicaRap Working Notes
Criteria ; Design a Metal 3D Printer , that produces dimensionally finished parts +- 1µ m over 20mm, largly self reproducing, electrical supply limited to single phase ( ie not 3 Phase,), minimum consumables beyond metal powder ( avoiding need for e.g.argon gas ... etc,),cost for parts less than a small car, buildrate can be slow i.e. .2KG per hour, no bigger than a wardrobe.
Due to lack of control in metal powder deposition in conventional ebeam 3D printing (e.g arcam 3d) a tolerance of 300µ in the Z axis is a typical with 10µ powder,( Lowder power sizes are prone to magnetic forces and typically unwieldy, though powder demagnetization and non ferrous construction is a possibility ), So using multi pickup Scanning Electron Microscope (SEM) combined with image processing the suedo stereo SEM picture data to true dimensional 3D data, Enabling sub µ metal height measurement. Z axis dimensional mistakes in any layer can be found and corrected using Electron beam machining EBM / ebeam vaporization of metal. This brings the XYZ axis to 20µ error over 20mm (T7). Future stage in development might include Ion beam etching gun to take dimensions to sub µ level.
This has 5 elements; electron gun, High Vacuum chamber, roughing pump, oil diffusion pump and metal powder dispenser.
Design Discussion
3KW 100 KV hot cathode gun
Stainless steel High vacuum 10-5 Tor / (mm mercury) NiCr Alloy (10-16) Hexagonalx40 halfhexagonalx16 endpiecesx16 384 bolts copper wire, future ; airlock so print while repump, main door Viton O ring (Euro ).
Vane pump ( initially purchased)
using existing EBS build design
options include ; screw/ trough design; feed chamber build chamber; others
A rough sketch made in Blender of a vacuum chamber made from hexagonal parts printed in a MetalicaRap. Anders
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Forum thread
Current status
Based in Copenhagen Denmark Labitat.dk Electron gun test repstrap vacuum chamber including pumps and gauges under electrical maintenance. Current tech team; 5 software developers, 1 Ultra high vacuum metal deposition specialist, 1 High voltage system designer, a theoretical physisist. We are particularly looking out for experienced electron gun designers (Electron beam welding/accelerator).
It would be great for another team to be set up in another part of the world to inspire each other!
Criteria ; Design a Metal 3D Printer , that produces dimensionally finished parts +- 1µ m , largly self reproducing, electrical supply limited to single phase ( ie not 3 Phase,), minimum consumables beyond metal powder ( avoiding need for e.g.argon gas ... etc,),cost for parts less than a small car, buildrate can be slow i.e. .2KG per hour, no bigger than a wardrobe.
Do get in touch if you want to build a team in your area.
Related Projects
Files and Parts
Sub Assemblies and Related
EBS=Electron beam sinterer/melting.
sequence - electron gun parts repstrapped EBS. Assembled tested in repstrap vacuum chamber. Metal powder deposition mechanism parts repstraped EBS . Gun depoosition assembled tested. MetalicarapVacuumChamber parts Electron beam sintered by our system. MetalicarapVacuumchamber assembled tested. 5 Elements assembled and tested.
Downloads
Photos and Drawings
More Examples
Practical manufacturing walk through Electricity is 2kwh per hour .5Euro/hr
Part A Stainless size 300x300x200mm 15Kg
10µ Stainless powder (40Euro/kg) melt print 100µ Z layer thickness
1 minute per Z 100µ each layer heated melting-point – 20 0C then printed by beam
3.4 minute per Every 10th layer Z axis correction ;
SEM ( part assumed to occupy 1/9 of whole print area; 1/9* 300*300=10 000mm2 measurement at every 10µ, SEM picture 500x500 pixel so 5mmx5mm, So for 10,000mm2 need 400 SEM pictures 10,000/25= 400 4x pictures from 4 picups gives effect of different angles? for 3D picture reconstruction so real distances, 400 5mmx5mm pictures, 250ms a picture ( Risk of underestimate factor x100 ) 1.4min
Remove metal by Vaporization 1ms per 70µ diameter spot area 4000x10-6 mm2 ( 850µs duration & 150µs beam movement) 1/10 of part high(Risk of underestimate factor x2) ( 1/10*10 000mm2/ 4000x10-6 mm2= 1x105 spots 1x105 spots*1ms= 100Sec 2min
Time so far 200* Z correction layers 3.4 Min each + 1800 printed layer 1min each = 2480 min ( 1.7 days)
To add a 40mmx4mm = 160mm2 bearing surface by removing up to 40µ to achieve 0.1µ specification Ion beam abrasion 20min per 1mm2 160*20min =3200min
Time total so far 200* Z correction layers 3.4 Min each 1800Min + 1800 printed layer 1min each 1800 = 2480 Min + ion beam bearing surface 3200= 5680( 4 days)
Cost 665 Euro materials 600Euro Electricity 65 Part B Aluminium size 300x300x20mm 1.5Kg Aluminium 15Euro 10µ powder
Time 20* Z correction layers 3.4 Min each + 180 printed layer 1min each = 248 Min 4 hours No ion beam surfacing Cost 25 Euro materials 22 Euro Electricity 3 Euro
Powder
Stainless steal powder
powder injection moulding
Aluminum powder 15 Euro/Kg 10µ metal injection moulding stainless steel powder, carbon chromium 40Euro a kg. 74µ 200mesh Aluminum powder 15 Euro/Kg 10µ