Technologies
Understand additive manufacturing's categories, technologies, materials, post-processes and terminology.
Printer Categories
AM's 7 printer category types.
The American Society for Testing and Materials International (ASTM) have defined the seven categories of Additive Manufacturing into which all of the different types fit. These are the recognised industry standard printer category classifications.
Powder Bed Fusion
Powder Bed Fusion is where a source of thermal energy (a highly focussed laser or electron beam) is focused on a bed of powder material. This then sinters the powder in each successive cross-sectional layer to form the final object.
Parts printed with Powder Bed Fusion technologies with polymer powder materials are always done so support-free. Those parts printed in metal powders have always required support structures to anchor them to the build plate. Recent developments are enabling support-free DMLS for certain geometries.
7 technologies
DMLS
Direct Metal Laser Sintering
Fuses metal powder with a high-power laser into fully dense parts with wrought-equivalent properties.
EBM
Electron Beam Melting
Melts metal powder with an electron beam in a vacuum, leaving parts largely free of residual stress.
SLM
Selective Laser Melting
SLM parts are built within a build chamber.
SLS (Benchtop)
Selective Laser Sintering
SLS (Benchtop) parts are built within a build chamber.
SLS (Fine Detail Resolution)
Selective Laser Sintering
SLS (Fine Detail Resolution) parts are built within a build chamber.
SLS (Industrial)
Selective Laser Sintering
Uses a CO2 laser to sinter polymer powder into solid 3D structures. No support structures required.
Advantages
- Powder Bed Fusion parts have tolerances equal to Vat Photopolymerisation, but are generally more robust.
- It can produce parts with robust complex geometry.
- The mechanical properties of metal parts are comparable to machining and casting.
- It is capable of producing functional plastic parts.
- Multiple parts can be produced within the same build.
- No support structures are required during the build process (All SLS types and CMF).
- Used metal powder can be 100% recycled.
- Proprietary post processing technology can improve the surface of polymer parts and accurately and consistently dye them.
Disadvantages
- Long print time and costly post-processing of metals.
- All SLS and CMF require build chambers to cool down for prolonged periods after the sintering is complete.
- Materials are highly processed and therefore expensive.
- Processes are electricity use intensive, especially when sintering metals.
- Powder materials mean that these technologies are only suited to workshop (CMF, SLS (Benchtop)) and industrial environments.
- Parts have variable surface texture quality that requires finishing if smoothness is required.
- Parts can experience thermal distortion – primarily with polymer parts and attention needs to be paid to heat distribution within multipart build preparation.
AM Environments
Like any machinery, it is important that it and any ancillary equipment are installed, operated and maintained in the appropriate environment.
These printer technologies can be used in practical environments where recognised studio or workshop protocols are observed.
Some of them require additional equipment as part of their processes which need to be understood and accommodated:
DLP
Digital Light Processing
DLP parts are built off a lifting build platform.
FFF (Large Format)
Fused Filament Fabrication
FFF (Large Format) parts are built on a build plate surface.
PolyJet
Jets ultra-thin photopolymer layers cured on contact, for colour-accurate, tactile prototypes.
PMSL
Projection Micro Stereolithography
PMSL parts are built off a lifting build platform.
SLS (Benchtop)
Selective Laser Sintering
SLS (Benchtop) parts are built within a build chamber.
SLA (Benchtop)
Stereolithography
SLA (Benchtop) parts are built off a lifting build platform.