Chapter 5.1 Additive Manufacturing Flashcards
What are the advantages of AM?
- Create complex geometries
- Customise every item
- Lower fixed costs (No tools + moulds)
- Rapid prototyping (Less fiscally risky to produce)
- Less waste material
What are the drawbacks of AM
- Higher costs for large production runs
- Less material choics / colours / finishes
- Limited strength & endurance
- Lower precision
What is the purpose of AM supports?
- Prevent deformation & curl
- Separate part from platform
- Anchor unattached sections
What are the Advantages of STL?
- Simple method of representing 3D CAD data
- De facto standard
- Small and accurate files for certain shapes
What are the disadvantages of STL?
- Redundant information eg. Duplicate vertices & edges -> Larger file size
- Geometry flaws generated from CAD models, needs repairing
- Long time to slice large STL files
Problems in STL Files
- Missing Facets / Gaps
- Degenerate Facets
- Overlapping Facets
Subtypes of binder jetting
- ColorJet Printing (CJP)
- Digital Part Materialisation (DPM)
Subtypes of Material Extrusion
- Fused Deposition Modelling (FDM)
Subtypes of Material Jetting
- Polyjet
Subtypes of PBF (Powder Bed Fusion)
- Selective Laser Sintering (SLS)
- Selective Laser Melting (SLM)
- Electron Beam Melting (EBM)
- Multi Jet Fusion
Vat Photopolymerisation Subtypes
- Stereolithography (SLA)
- Digital Light Processing (DLP)
Subtypes of DED (Directed Energy Deposition)
- Electron Beam Direct Manufacturing (EBDM)
- Laser Metal Deposition (LMD)
Sheet Lamination Subtypes
- Laminated Object Manufacturing (LOM)
- Selective Deposition Lamination (SDL)
- Ultrasonic Additive Manufacturing (UAM)
Sources of energy in DED (Directed Energy Deposition)
- Laser
- Friction stir
- Electron beam
- Arc
Binding mechanisms in PBF (Powder bed fusion)
- Solid state sintering
- Chemically induced binding
- Liquid phase sintering (Partial melting)
- Full melting
Advantages of binder jetting
- Wide range of materials (polymers, metals, ceramics (sand))
- Faster (Main bulk of material that’s actually deposited is via powder spreader, small portion through print heads)
Disadvantages of binder jetting
- Poor accuracy and surface finish
- Post-processing (Infiltration / furnace / sintering) needed for high density / good mechanical properties (Binders need to be removed)
Advantages of CJP (Colour Jet Printing)
- High speed
- Versatile
- Simple to operate
- Minimal material wastage
- Complex colours
Disadvantages of CJP (ColorJet Printing)
- Limited functional parts (Relative to SLS)
- Poor surface finish
Advantages of DPM (Digital Part Materialisation)
- Fast (85000 cm^3 / hr)
- Flexible
- Reliable
- Large Parts (1800 x 1000 x 700 mm)
Disadvantages of DPM
(Digital Part Materialisation)
- Large space
- Limited materials (Metal / sand)
Advantages of DED
(Directed Energy Deposition)
- Can produce fully dense parts
- can repair defective / damaged components
Disadvantages of DED
(Directed Energy Deposition)
- Poor resolution + surface finish
- Low complexity only
Advantages of EBDM
(Electron Beam Direct Manufacturing)
- Fast and cost effective for large metal parts
- Multi-material printing
- High deposition rate (relative to other DEDs)
- Near 100% usage efficiency -> Less material waste (Compared to powder bed fusion)
- Wire feedstock less flammable, cheaper than powder feedstock
Disadvantages of EBDM
(Electron Beam Direct Manufacturing)
- Poor resolution (No fine details)
- No supports (No complex internal geometries)
- Only weldable metals that aren’t highly flammable
Advantages of LMD
(Laser Metal Deposition)
- Superior material properties (Fully dense)
- Complex parts (Worse than powder bed fusion, better than EDM)
- Add material on to existing parts (Use for repairs / hybrid manufacturing)
- Multiple materials can be blended
- Low powder cost (Wide powder size range - 150-200mm usually)
Disadvantages of LMD
(Laser Metal Deposition)
- Geometric complexity (Worse than powder bed fusion)
- surface finish (Rougher than powder bed fusion)
- Dimensional accuracy (Worse than powder bed fusion)
Advantages of FDM
(Fused Deposition Modelling)
- Can fabricate functional parts
- Minimal wastage
- Ease of support removal
- Ease of material change
- Large build volume (eg. 900 x 900 mm)
Drawbacks of FDM
(Fused Deposition Modelling)
- Limited accuracy (By filament, between 0.2-0.5mm)
- Slow process (Restricted by extrusion rate / flow rate)
- Unpredictable shrinkage (Due to rapid cooling, needs compensation)
Advantages of Polyjet
- High quality
- High accuracy
- Fast process speed
- Smooth surface finish
- Wide range of materials (Acrylic, plastic, rubber etc)
- Easy usage (Cartridges)
- SHR (Single head replacement) - Replace nozzles instead of whole unit
- Safe, clean, Low noise
- Multiple materials in 1 run (Also multiple colours)
Disadvantages of Polyjet
- Post-processing required to wash away support material
- Wastage of support material
Advantages of PBF
(Powder bed fusion)
- Wide range of materials (Polymers, metals, ceramics)
- Fast
Disadvantages of PBF
(Powder bed fusion)
- Support structures needed for metals
- Expensive and time consuming post processing (for metals)
- Lower resolution and accuracy (Compared to liquid processes for polymers)
Advantages of SLS
(Selective Laser Sintering)
- Good part stability (Precise controlled environment)
- Wide range of processing materials (Any material in powder form)
- No parts supports required
- Little postprocessing required
- No post-curing required
Disadvantages of SLS
(Selective Laser Sintering)
- Large physical size
- High power consumption (High laser wattage)
- Poor surface finish (Large particle size of powders)
Advantages of SLM
(Selective Laser Melting)
- High quality metal parts (100% density)
- Large range of metal materials (Stainless steel, titanium, aluminium, etc)
- Fast and low cost
- High accuracy
- Complex geometries
Disadvantages of SLM
(Selective Laser Melting)
- Large physical size
- High power consumption
- Slow process (Compared to machining)
EBM Advantages
(Electron Beam Melting)
- Superior material properties (Fully dense parts)
- Excellent accuracy (Less shrinkage, no impurities from oxides)
- Excellent finishing
- Good build speed
EBM Disadvantages
(Electron Beam Melting)
- Need to maintan vacuum chamber
- High power consumption
- Gamma rays
Multi Jet Fusion Advantages
- Fast (Faster than FDM and SLS)
- Low cost per part (Cheaper than FDM and SLS)
- High quality functional parts
- High accuracy and fine details
- Add additional parts whilst printing
Multi Jet Fusion Disadvantages
- Only STL files can be used
- Post-processing required to clean and cool part
- Only thermoplastics and elastomers can be used
Vat Photopolymerisation Advantages
- High accuracy, resolution, good surface finish
- Compatible with different sizes and machine configs
Vat Photopolymerisation Disadvantages
- Only photopolymers
- Lower impact strength and durability compared to injection moulding
- Material ages and mechanical properties degrade over time
SLA Advantages
(Stereolithography)
- Unattended round the clock operation
- Various build volumes
- High accuracy
- Good surface finish
- Wide range of materials
SLA Disadvantages
(Stereolithography)
- Support structures required
- Post-processing required for support removal
- Post-curing required to ensure structure integrity
DLP Advantages
(Digital Light Processing)
- High building speed (Faster than SLA)
- Office friendly process
- Small quantity of resin during build
- No wiper / leveler (No stability issues to part)
- Less shrinkage (immediate curing)
- Safe supply cartridges (Lower risk of user coming into contact)
- Additional components (Integrated into system to allow for higher quality tougher parts)
DLP Disadvantages
(Digital Light Processing)
- Limited build volumes (Structures build from bottom)
- Peeling of completed part (May damage model during peeling process)
- Post-Processing (And maybe post curing) required
Sheet Lamination Advantages
- High speed
- Low cost
Sheet Lamination Disadvantages
- Strength depends on bonding strength
- Highly anisotropic (Non-uniform), may delaminate due to weak interlayer bonding
- Material wastage
SDL Advantages
(Selective Deposition Lamination)
- Low cost (Its literally paper)
- High precision (0.012mm precision, 0.1mm accuracy)
- Safe (Its literally paper)
- Eco-friendly (Its literally paper)
- High resolution in colour printing (More than 1 million colours, 5760 × 1440 × 508 dpi)
SDL Disadvantages
(Selective Deposition Lamination)
- Low strength (Its literally paper)
- Small build volume (Only A4 / letter size area because its literally paper)
UAM Advantages
- No concerns on shrinkage, residual stress or distortion (Low temp operation)
- Can process multiple materials which are dissimilar
UAM Disadvantages
- Low interfacial bonding and bonding strength
- Fixed layer thickness
