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Tag: DMLS

  • LPBF vs DMLS vs SLM vs SLS: What the Terms Actually Mean

    LPBF vs DMLS vs SLM vs SLS: What the Terms Actually Mean

    LPBF, DMLS, SLM, DMLM and SLS are often treated as competing process names. In reality, some are standardized process categories, while others are historical or supplier-associated terms. The terminology matters because confusing metal and polymer powder-bed processes can lead to incorrect material, design and qualification assumptions.

    For process-neutral technical communication, use the standardized category first and add the commercial term only when it helps identify a specific machine or legacy data set.

    The clearest terminology

    TermWhat it usually meansRecommended use
    PBF-LB/MPowder bed fusion of metal using a laser beamMost precise standardized-style notation for metal laser powder bed fusion
    LPBF or L-PBFLaser powder bed fusionWidely accepted general term for metal laser powder-bed processes
    DMLSDirect Metal Laser SinteringLegacy and supplier-associated term, strongly linked with EOS; commonly refers to metal LPBF
    SLMSelective Laser MeltingHistorical industry term for metal LPBF; also associated with the former SLM Solutions brand
    DMLMDirect Metal Laser MeltingSupplier-used term for metal LPBF, notably used in parts of the GE Additive ecosystem
    PBF-LB/PPowder bed fusion of polymer using a laser beamPrecise category for laser-based polymer powder bed fusion
    SLSSelective Laser SinteringMost commonly used for polymer powder bed fusion; avoid using it as a generic label for modern metal LPBF
    PBF-EB/MPowder bed fusion of metal using an electron beamProcess-neutral term for electron-beam metal powder bed fusion

    LPBF: the broad industrial term

    Laser powder bed fusion describes a process in which a laser selectively melts regions of a thin metal-powder layer. After each layer, the build platform moves and the recoater spreads fresh powder. The cycle continues until the part is complete. The finished component normally requires depowdering, stress relief or heat treatment, removal from the build plate, support removal and often machining or surface finishing.

    LPBF is the preferred broad term because it describes the physical process without implying a particular machine supplier. The notation PBF-LB/M goes one step further by identifying the process category, energy source and material class.

    Schematic representation of laser powder bed fusion
    LPBF illustration originally credited to Fraunhofer

    DMLS, SLM and DMLM: different labels, not fundamentally different physics

    Older explanations often claim that DMLS only sinters metal powder while SLM or DMLM fully melts it. That distinction is misleading for modern commercial metal systems. Production metal powder-bed machines marketed under these names generally create a melt pool and consolidate metal through melting and solidification.

    The practical differences between two metal LPBF systems usually come from machine architecture, laser configuration, gas flow, recoating system, parameter set, powder specification, software, monitoring, build strategy and validated post-processing — not from the word used in the acronym.

    DMLS

    DMLS is a widely recognized commercial and historical term associated with EOS. Engineers may still encounter it in machine names, material data, qualification documents and customer specifications. When discussing the general process, however, LPBF or PBF-LB/M is clearer.

    SLM

    SLM became a common industry term for fully melted metal-powder processes and was also embedded in the name SLM Solutions, now Nikon SLM Solutions. It remains understandable, but it is less neutral than LPBF.

    DMLM

    DMLM is another supplier-associated expression for metal laser melting. It should be interpreted as a metal LPBF route unless the governing process specification defines something more specific.

    Why SLS should usually be reserved for polymers

    Selective laser sintering is most commonly used for polymer powder bed fusion, especially polyamide systems. The powder surrounding the part provides support, so polymer SLS parts usually do not need the attached support structures typical of metal LPBF. Thermal control, powder refresh, nesting strategy and post-processing are also fundamentally different from the metal route.

    Using SLS as a catch-all term for metal and polymer processes creates confusion. A better distinction is:

    • Metal: LPBF or PBF-LB/M.
    • Polymer: SLS or, in standards-oriented writing, PBF-LB/P.
    • Electron-beam metal: PBF-EB/M.

    What actually changes part performance

    The acronym does not determine the final properties. The following variables matter far more:

    • Alloy and powder specification, including chemistry, particle-size distribution, morphology and reuse history
    • Machine model, laser configuration, scan strategy, gas flow, recoater and calibration status
    • Build orientation, support and anchoring strategy, part location and thermal history
    • Layer thickness, energy input and the validated process parameter set
    • Stress relief, solution treatment, aging, hot isostatic pressing and other thermal operations
    • Support removal, machining, surface finishing and cleaning
    • Inspection plan, test coupon strategy and acceptance criteria

    A practical naming rule for engineers

    1. Use LPBF in general engineering communication about laser-based metal powder bed fusion.
    2. Use PBF-LB/M when writing standards-oriented specifications, process maps or qualification documents.
    3. Retain DMLS, SLM or DMLM when quoting a machine supplier, legacy document, trademark, customer specification or established program terminology.
    4. Use SLS mainly for polymer powder bed fusion.
    5. Do not infer material properties from the acronym. Reference the qualified machine–material–parameter–post-process route.

    LPBF vs SLS: quick comparison

    CharacteristicMetal LPBF / PBF-LB/MPolymer SLS / PBF-LB/P
    Typical feedstockMetal alloy powderThermoplastic powder, commonly polyamides
    ConsolidationLocalized melting and solidificationThermal fusion of polymer particles
    Attached supportsCommonly required for anchoring and heat transferUsually not required because surrounding powder supports the part
    AtmosphereControlled inert environment; reactive alloys require strict oxygen controlHeated process chamber with controlled thermal history
    Post-processingDepowdering, heat treatment, cut-off, support removal, machining/finishing as neededCooling, depowdering, cleaning, dyeing or finishing as needed
    Main design concernThermal stress, distortion, supports, recoater interaction, trapped powderThermal shrinkage, nesting, powder aging, escape paths and surface texture

    Frequently asked questions

    Is DMLS a sintering process?

    Despite the name, modern commercial DMLS systems used for structural metal parts generally form a melt pool. Treating DMLS as a fundamentally lower-density partial-sintering route is not a reliable technical distinction.

    Are SLM and LPBF the same?

    In most present-day industrial discussions, SLM refers to a metal LPBF process. LPBF is the broader and more supplier-neutral term.

    Can SLS print metal?

    The term has historically been used broadly, but modern engineering communication normally reserves SLS for polymer powder bed fusion. For metal, use LPBF or PBF-LB/M.

    Does the terminology affect qualification?

    Qualification is tied to the defined production route, not to a marketing acronym. The governing specification should identify equipment, feedstock, parameters, post-processing, inspection and change-control requirements.

    Conclusion

    LPBF is the most useful general label for laser-based metal powder bed fusion. DMLS, SLM and DMLM are best understood as legacy or supplier-associated names within that process family. SLS is normally a polymer process. Clear terminology reduces ambiguity, but the final part is defined by the complete, qualified manufacturing route.

    Related Addithive resources: Design for LPBF · Metal AM Process Selection

    References and further reading

  • History of Additive Manufacturing: From Early Patents to Industrial Production

    History of Additive Manufacturing: From Early Patents to Industrial Production

    The history of additive manufacturing is not a single invention story. It is a sequence of advances in photopolymers, powder processing, extrusion, digital geometry, machine control, materials and qualification. The modern industry emerged when these elements became reliable enough to create repeatable physical parts directly from digital data.

    The most important shift was not from “no 3D printing” to “3D printing.” It was from rapid prototyping to controlled manufacturing of accepted end-use parts.

    Before modern AM: layered representation and automated fabrication

    Long before commercial 3D printers, inventors and researchers explored ways to reconstruct three-dimensional form from cross-sections, projected images and automated deposition. Nineteenth-century photosculpture and topographic layering anticipated the idea of building a shape from sequential slices, but these methods were not digital additive manufacturing in the modern industrial sense.

    Science-fiction descriptions in the mid-twentieth century also imagined machines that created objects from drawings or deposited material. These stories influenced the cultural imagination, but the technical foundations required computer-aided geometry, numerical control and suitable material systems.

    1980–1981: Hideo Kodama and layered photopolymer models

    Hideo Kodama described an automatic method for fabricating three-dimensional plastic models using a photo-hardening polymer. His Japanese work and patent record from 1980–1981 are among the earliest documented modern approaches to forming 3D objects by successively curing layers from cross-sectional data.

    Kodama’s work demonstrated the central architecture of vat photopolymerization: digital sections, controlled light exposure and successive solid layers.

    1984–1986: stereolithography becomes a commercial platform

    Charles W. Hull filed a foundational stereolithography patent in 1984. The system used radiation to selectively solidify layers in a fluid medium according to cross-sectional information. Hull later co-founded 3D Systems, helping turn stereolithography from a laboratory concept into a commercial rapid-prototyping platform.

    This period established several ideas that still define AM workflows:

    • Represent the object as digital cross-sections.
    • Build the geometry sequentially.
    • Use computer-controlled motion and energy delivery.
    • Separate digital design from physical tooling.
    • Use support and post-processing to complete the part.

    1986 onward: selective laser sintering

    Carl Deckard’s selective-sintering work at the University of Texas used a laser to selectively consolidate regions of a powder layer. The foundational patent record has a 1986 priority date. Powder-bed processing expanded AM beyond liquid photopolymers and created a path toward durable polymer parts and later a broad family of metal powder-bed systems.

    One major advantage was that surrounding powder could support complex shapes, reducing the need for attached supports in polymer systems. Powder handling, thermal control and material reuse became new industrial challenges.

    1989 onward: material extrusion and FDM

    S. Scott Crump’s foundational extrusion patent has a 1989 priority date and describes creating three-dimensional objects by dispensing material layer by layer. Stratasys commercialized the process under the Fused Deposition Modeling trademark.

    Material extrusion later became the dominant architecture of low-cost desktop printing. Outside the trademarked term FDM, Fused Filament Fabrication became a common generic description for filament-based systems.

    1989–1990s: MIT and three-dimensional printing by binder jetting

    Researchers at the Massachusetts Institute of Technology developed a process that spread powder and selectively deposited binder to join chosen regions. The foundational patent family has a 1989 priority date and used the phrase “three-dimensional printing.”

    This work became the basis for binder jetting across visual models, ceramics, metal parts and printed sand molds or cores. It also helped popularize “3D printing” as a broader public term.

    The 1990s: rapid prototyping becomes an industry

    During the 1990s, stereolithography, selective laser sintering, material extrusion, binder-based systems and material jetting became commercial rapid-prototyping tools. The main value proposition was speed: engineering teams could evaluate geometry before investing in molds, dies or production tooling.

    This era also exposed limitations that remain relevant:

    • Digital models needed repair and reliable file translation.
    • Machine-specific build preparation became necessary.
    • Supports, curing, depowdering and finishing affected lead time.
    • Prototype material properties often differed from production materials.
    • Accuracy and surface quality depended on process and orientation.

    Metal AM expands

    Metal additive manufacturing developed through several routes rather than one technology:

    • Laser powder bed fusion: selectively melts metal powder using a laser.
    • Electron-beam powder bed fusion: processes conductive metal powder under vacuum with a hot bed.
    • Directed energy deposition: delivers powder or wire into a laser, arc or electron-beam melt pool.
    • Metal binder jetting: prints a green part followed by depowdering, debinding and sintering.
    • Sheet lamination: bonds metal foils, including ultrasonic solid-state routes.

    The rise of metal AM shifted the industry from shape demonstration toward materials engineering, metallurgy, defect control, heat treatment, machining, NDT and qualification.

    2004–2008: RepRap and open-source desktop printing

    Adrian Bowyer introduced the RepRap concept online in 2004. The goal was a freely available rapid-prototyping machine able to manufacture many of its own plastic parts. The project combined open-source hardware, software and community collaboration.

    In May 2008, the RepRap project documented a working “child” machine assembled using parts produced by a parent machine. RepRap did not invent extrusion printing, but it helped democratize it and seeded a large ecosystem of desktop printers, slicers, firmware projects and community-designed machines.

    The 2010s: patents expire and access expands

    As key early patents expired, competition increased in desktop and industrial systems. Entry-level machines became less expensive, while industrial platforms added better process control, multiple energy sources, larger build volumes and more capable software.

    The decade also produced a sharp contrast between consumer hype and industrial reality. Desktop printers became widely visible, but reliable production still required process knowledge, controlled materials and post-processing.

    Medical, dental and hearing-aid industrialization

    Medical and dental applications demonstrated that AM could support large-scale customization when digital workflows and validated materials were tightly controlled. Hearing-aid shells, orthodontic models, surgical guides, dental devices and porous orthopedic implants became important examples.

    The lesson was broader than healthcare: customization can scale when unique geometry flows through a standardized production cell.

    Aerospace and propulsion: from demonstration to qualified hardware

    Aerospace adoption focused attention on part consolidation, complex internal passages, high-value alloys and weight reduction. Fuel hardware, heat exchangers, rocket components, structural brackets and tooling became prominent applications.

    The industry also established a harder truth: a successful build is not the same as a qualified flight part. Feedstock control, machine qualification, heat treatment, HIP, machining, inspection, material allowables and change control became central.

    From rapid prototyping to additive manufacturing

    The terminology evolved as the purpose changed:

    TermWhat it emphasized
    Rapid prototypingFast creation of development models before production tooling
    Solid freeform fabricationBuilding 3D geometry without conventional shape-specific tooling
    Layer manufacturingSuccessive formation of cross-sectional layers
    3D printingAccessible public term originally associated strongly with binder-based printing
    Additive manufacturingIndustrial production, process control and end-use parts

    Standards and common vocabulary

    As adoption grew, inconsistent commercial terminology became a barrier. ISO and ASTM collaboration created common definitions and process categories. ISO/ASTM 52900:2021 remains the current confirmed vocabulary standard and organizes AM around standardized technical concepts rather than trademarks alone.

    This standardization supports communication across design, procurement, qualification, regulation and supply chains. Read Addithive’s seven AM process categories guide.

    The current industrial phase

    Modern AM development is less about proving that a geometry can be printed and more about solving industrial bottlenecks:

    • Qualification cost and transfer between machines or sites
    • First-pass yield and process stability
    • Powder, resin, wire and material genealogy
    • Post-processing and furnace capacity
    • Support removal, machining and surface finishing
    • Inspection of complex internal geometry
    • Digital thread and production data
    • Cost per accepted part at repeat volume

    This is why the industry’s next phase is defined by industrialization rather than another sequence of “world-first” demonstration prints.

    Timeline summary

    PeriodMilestoneWhy it mattered
    1980–1981Kodama’s layered photopolymer workEarly modern description of digitally controlled layer curing
    1984Hull’s stereolithography patent priorityFoundation for commercial vat photopolymerization
    1986Deckard’s selective-sintering patent priorityPowder-bed route for durable polymer and later metal ecosystems
    1989Crump extrusion patent priorityFoundation for commercial FDM and later desktop FFF
    1989MIT 3D-printing patent priorityFoundation for binder jetting and wider use of the “3D printing” term
    1990sCommercial rapid-prototyping expansionAM enters engineering-development workflows
    2004RepRap introduced onlineOpen-source desktop printer ecosystem begins
    2008RepRap documents a working child machineDemonstrates community-based partial self-replication
    2010sDesktop access and industrial metal AM expandConsumer visibility and end-use manufacturing grow simultaneously
    2010s–2020sMedical, dental and aerospace qualification maturesRepeat customization and critical end-use parts become credible
    Current phaseIndustrialization and bottleneck removalFocus moves to yield, post-processing, qualification and economics

    Conclusion

    Additive manufacturing evolved through multiple inventions and communities rather than one uninterrupted line. Photopolymerization, powder-bed processing, extrusion, binder jetting and open-source hardware each changed what the technology could do and who could use it. The decisive industrial transition came when organizations learned to control the entire route from digital design to accepted part.

    Related Addithive resources: Introduction to Additive Manufacturing · Seven AM Process Categories · AM Bottleneck Map

    Primary references