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Karteikarten

7 ASTM Processes

Jack Moule AM Masters Englisch 34 Karten

Vat photopolymerisation process

Karten in diesem Stapel (34)

  1. 1What are the 7 ASTM Processes1. Material Extrusion ege Fused deoposition modelling
    2. Vat photopolymerization eg steriolithography
    3. Powder bed fusion eg selective laser sintering
    4. Material jetting eg objet
    5. Binder jetting
    6. Directed energy deposition eg laser engineered net shaping
    7. Sheet lamination eg laminate object manufacture
  2. 2Material ExtrusionA material is selectively dispensed through an orifice or nozzle
  3. 3Vat PhotopolymerisationA liquid photopolymer in a vat is selectively cured by light activated polymerization
  4. 4Powder bed fusionThermal energy selectively fuses regions of a powder bed
  5. 5Material JettingDroplets of build material are selectively deposited
  6. 6Binder jettingA liquid bonding agent is selectively deposited to join powder materials
  7. 7Directed energy depositionFocussed thermal energy fuses material by melting as the material is being deposited
  8. 8Sheet laminationSheets of material are bonded to form an object
  9. 9Materials all processes1. Material extrusion - Polymers eg ABS, PLA, PC, PPSU, waxes, chocolate
    2. Vat photopolymerization - photocurable resins, can do ceramics by loading of ceramic into photopolymer which acts as a binder,
    3. Powder bed fusion
    Sintering (polymers) - nylon, Polystyrene, PEEK
    Melting - stainless steel, aluminium alloy, titanium alloy
    Also ceramics by binder sintering
    4. Material jetting - polymers and waxes
    5. Binder jetting - starch and cellulose, ceramics and metal possible by binding metal with polymer based binder, sintering and infiltration.
    6. Directed energy deposition - Metals
    7. Sheet lamination - Paper, polymer or stacking ceramics or UC bonding thermally incompatible materials.
  10. 10What is an STL fileAn approximate surface representation of the CAD file geometry compiled through the use of a tessellated surface.
    The triangles act as a air tight mesh over the surface.
    Allows cartesian coordinate data to be extracted from the CAD file and used by the AM process to manufacture the layers.
  11. 11Material extrusion process1. Polymer filament is forced through a heated extrusion head where it is forced through a small diameter nozzle by drive wheels.
    2. The moving head traces out the required pattern for the particular layer in x-y, determined from the STL file, along with the required support material.
    3. Build platform moves down one layer and the process is repeated.
  12. 12Advantages material extrusion1. Office friendly - stable materials in non-hazardous form, simple operation.
    2. Reliable and low maintenance costs.
    3. Cheap materials and machines with open access.
    4. Parts mechanically and chemically smoothed, painted and coated.
    5. Common engineering polymers.
    6. Some soluble supports.
  13. 13Disadvantages material extrusion1. Support.
    2. Stair stepping - poor surface finish.
    3. Anisotropic material properties - weaker in z.
    4. Accuracy not as good as traditional machining.
    5. Dense, accurate parts take longer.
  14. 14Vat photopolymerisation process1. Laser scans liquid photopolymer surface causing it to polymerise depending on x-y data for particular layer from stl file.
    2. Platform drops one layer.
    3. Recoating step with sweeper.
    4. Process repeated.
    Post processing: Support removal, suncured resin removal with solvent, post cure.    Vat photopolymerisation process
  15. 15Advantages vat photopolymerisation1. Very accurate
    2. Good surface finish - similar to injection moulded parts.
    3. Parts mechanically and chemically smoothed, painted and coated.
    4. Large build volumes available.
    5. Materials mimic traditional engineering materials.
    6. Low energy input compared to thermal systems.
    7. Can be used for highly accurate investment casting.
  16. 16Disadvantages1. Support structures.
    2. Resin toxic.
    3. Materials have to be photocurable resins.
    4. Materials are hygroscopic.
    5. Age in sunlight.
    6. Materials/machines expensive.
    7. Material change requires thorough clean using solvent.
  17. 17Powder bed fusion process1. Powder particles in pre-heated state in build volume.
    2. Additional heat input causes necking.
    3. Grain boundaries form and porosity reduces.
    4. Powder fused
    For melting - heat input causes material to melt and flow and grain boundaries form on rapid cooling.
    For binder sintering - Polymer-coated particles sintered together, green parts fired in furnace to burn off binder and part infiltrated.    Powder bed fusion process
  18. 18Advantages sintering and melting1. Partial material recycled (50%).
    2. Self supporting.
    3. Nesting.
    4. Tough parts suitable for functional testing.
    5. Minimal post-processing.
    6. Complex geometry possible.
    Melting
    1. Dense metallic components.
    2. Fully recyclable powder.
    3. Parts heat treated
  19. 19Disadvantages sintering and melting1. Distortion.
    2. Stresses on cooling, more for melting due to rapid phase change.
    3. High energy input - powder, build volume and additional heat, inert atmosphere.
    4. Delamination and trapped volumes.
    5. Rough surface finish.
    6. Build volume pre-heat and cool down take hours.
  20. 20Material jetting processObjet
    1. Photosensitive material is jetted.
    2. UV light cures each layer.
    3. Print head moves in x-y to build each layer.
    4. Platform moves down one layer and process repeated.    Material jetting process
  21. 21Advantages material jetting1. Multimaterials - functionally graded, different mechanical properties, soluble support, different colours.
    2. Good part edge quality.
    3. High resolution (40um features).
    4. Smooth surfaces
  22. 22Disadvantages material jetting1. Limited materials
    2. No metals/ceramics
    3. High material cost.
    4. Wastage through roller levelling process.
  23. 23Binder jetting process1. Powder spreading.
    2. Print head selectively deposits binder material.
    3. Platform drops one layer, next layer coated and process repeated.
    Post processing - Loose powder vacuumed, dry part thoroughly (porous and brittle), infiltration with secondary material for thermal, mechanical properties and reduce porosity.    Binder jetting process
  24. 24Advantages binder jetting1. Simple, low cost systems.
    2. Binder solution primarily water based.
    3. Colour.
    4. Fast process due to jetting.
    5. Very little waste.
  25. 25Disadvantages binder jetting1. Limited functional parts.
    2. Limited strength.
    3. Limited materials.
    4. Poor surface finish.
    5. Poor resolution - particle size distribution and wetting of binder.
    6. Multiple secondary processes.
  26. 26Directed energy depositione.g. Laser engineered net shaping
    1. Sheath gas compresses powder stream, prevents oxidation and ignition and improves wetting.
    2. Powder delivered to the focus of a laser beam to form a melt pool.
    3. Part driven on x-y stage to build part (or coat existing part) layer by layer.
    4. Melt pool cools rapidly resulting in fine microstructure and high hardness.
    Post processing to achieve final geometry.    Directed energy deposition
  27. 27Advantages directed energy deposition1. Fine microstructure results in high hardness equivalent to wrought products.
    2. Diverse control possible.
    3. High-density parts.
    4. Functionally graded materials.
    5. Good buy-to-fly ratio
    6. Faster deposition rate than powder bed fusion.
  28. 28Disadvantages directed energy deposition1. Requires inert atmosphere or vacuum environment.
    2. Poor resolution and surface roughness (near net shape and requires further machining).
    3. Not as complex geometry as powder bed fusion.
  29. 29Sheet lamination - Laminate object manufacture1. Heated roller bonds sheet.
    2. Cross section cut with laser.
    3. Platform descends.
    4. New layer prepared.
    5. Top sheet coated with adhesive.
    6. Raise platform to meet new layer
    Post processing: Support removal, parted sealed to prevent moisture ingress and distortion, sanded polished and painted.    Sheet lamination - Laminate object manufacture
  30. 30Advantages LOM1. Colour - inkjet or coloured paper.
    2. Simple and safe systems.
    3. No support.
    4. Cheap materials.
    5. No heating, powder or atmospheric control.
    6. Fast - only profile cut
  31. 31DIsadvantages LOM1. Lack of materials.
    2. Sealing required.
    3. Difficult to produce enclosed volumes.
    4. Not suitable for functional testing.
    5. Wasteful.
    6. Poor geometric complexity
  32. 32Ultrasonic consolidation1. Metal foil layer deposited.
    2. Rotating cylindrical sonotrode bonds layers through pressure and ultrasonic oscillation which causes atoms to move and bonds to form.
    3. Hybrid process - CNC milling    Ultrasonic consolidation
  33. 33Advantages UC1. Can embed objects due to compliance of process.
    2. Minimal stresses due to absence of liquid-solid phase change.
    3. Can bond thermally incompatible materials.
    4. No atmospheric control requirements.
    5. Accuracy dependent on CNC milling.
  34. 34DisadvantagesPoor geometric complexity

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Beschreibung
Masters AM Karteikarten am 7 ASTM Processes, erstellt von Jack Moule am 17/05/2016.
Erstellt von
Jack Moule
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