Addithive

Tag: LPBF

  • 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

    Company research and reading path updated 12 September 2026.

    From process terminology to company research

    Company / platformTechnology connectionWhat to verify
    Nikon / Nikon SLMMetal laser powder bed fusionOrder conversion, service demand and the contribution to Nikon as a whole.
    Carpenter TechnologyMetal powders and powder-management solutionsRecurring qualified powder demand, customer retention and separately disclosed financial contribution.

    Manufacturer evidence: Nikon SLM platform portfolio and Carpenter Additive powder capabilities. Supplier terminology identifies a process family; it does not demonstrate equivalent part qualification.

    Company exposure is a research starting point, not a stock recommendation. A relevant technology does not establish material revenue, attractive margins or a reasonable valuation. Check current filings, ownership, cash flow and customer concentration before drawing an investment conclusion.

    Continue with machine equivalence and LPBF production cost drivers.

    Take the next step: the free AM Bottleneck Atlas

    Assess laser powder bed fusion through the full production route. The Industrial AM Bottleneck Atlas 2026 connects manufacturing constraints with qualification, economics and company exposure.

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  • Design for Laser Powder Bed Fusion: A Practical DfAM Guide

    Design for Laser Powder Bed Fusion: A Practical DfAM Guide

    Designing for laser powder bed fusion (LPBF) is not the same as designing a conventionally manufactured part and then sending the CAD file to a printer. LPBF performance depends on the interaction between geometry, orientation, supports, heat flow, recoating, powder removal, post-processing and inspection.

    A good LPBF design is not merely printable. It is buildable, removable, heat-treatable, machinable, inspectable and repeatable.

    Start with the complete manufacturing route

    Before optimizing geometry, define the route from powder to accepted hardware. The sequence commonly includes build preparation, printing, controlled cooling, depowdering, stress relief, removal from the build plate, support removal, heat treatment, hot isostatic pressing when required, machining, surface finishing, cleaning and inspection.

    Each downstream operation creates design requirements. A channel that can be printed but not depowdered is not manufacturable. A thin wall that survives the build but distorts during cut-off is not robust. A datum that cannot be machined or inspected is not production-ready.

    1. Part orientation is a multi-objective decision

    Orientation affects support volume, thermal gradients, surface roughness, dimensional accuracy, build height, recoater exposure, mechanical-property direction, powder removal and post-processing access. There is rarely one universally best orientation.

    Orientation objectiveWhy it mattersTypical trade-off
    Reduce support volumeLowers material, removal effort and witness marksMay increase build height or distortion
    Protect critical surfacesDown-facing surfaces are usually rougher and less accurateMay require more supports elsewhere
    Improve heat flowStable thermal paths reduce distortion and local overheatingCan increase contact with the build plate
    Limit recoater riskTall, thin or poorly anchored features may deflect or collideA safer orientation may use more space
    Enable machiningDatums and critical interfaces need tool access and stock allowanceMachining-friendly orientation may not minimize print time
    Enable inspectionInternal features need suitable access or validated NDT methodsSome optimized internal geometries are difficult to verify

    Use build simulation and engineering judgment, but validate critical orientations with representative builds. Simulation quality depends on accurate material, process and boundary-condition inputs.

    2. Overhang rules are process-specific

    The familiar “45-degree rule” is only a screening heuristic. The minimum self-supporting angle depends on alloy, layer thickness, scan strategy, feature length, local heat accumulation, machine architecture and required surface quality. Short bridges, thin walls and curved surfaces can behave differently from large flat overhangs at the same nominal angle.

    Instead of applying a single angle limit, classify features by risk:

    • Down-facing surfaces: prone to roughness, dross, dimensional error and local overheating.
    • Large horizontal areas: high risk of distortion and poor surface condition.
    • Thin cantilevers: vulnerable to curling and recoater interaction.
    • Internal overhangs: difficult to support, remove and inspect.
    • Bridges and enclosed channels: sensitive to span, shape, heat flow and powder evacuation.

    3. Supports are thermal and mechanical tools

    Metal LPBF supports do more than hold a part against gravity. They anchor the component, conduct heat to the build plate, resist residual-stress-driven distortion and stabilize vulnerable features against recoater forces.

    A support strategy should define:

    • Where strong anchoring is needed and where low-contact supports are sufficient
    • How heat will flow from local hot spots to the build plate
    • How supports will be accessed and removed
    • Which surfaces can tolerate support witness marks
    • Whether the part will remain stable during stress relief and build-plate removal
    • How support volume affects cost, powder recovery and machining

    Supports should be designed together with the cut-off and machining plan. Minimizing support volume at the expense of build stability often increases total cost.

    Example of LPBF support structures
    Support design example originally credited to Materialise Magics

    4. Design for thermal stability

    LPBF creates steep, repeated thermal gradients. Residual stress, distortion, delamination and cracking risk depend on geometry, material, heat flow and scan strategy. Designers cannot control every process variable, but geometry can reduce sensitivity.

    • Use gradual section transitions rather than abrupt changes in mass.
    • Avoid isolated heavy sections connected to thin walls.
    • Add generous radii where stress and heat concentrate.
    • Keep long unsupported edges and broad flat surfaces under control.
    • Consider sacrificial ribs, strongbacks or machining stock where distortion risk is high.
    • Coordinate thin-wall limits with the qualified supplier and parameter set.
    • Use symmetry cautiously: symmetric CAD does not guarantee symmetric thermal history.

    Materials with high crack sensitivity or poor thermal conductivity may need tighter geometric constraints, platform preheating, specialized parameters or alternative processes.

    5. Plan powder removal from the first sketch

    Internal channels, lattices and cavities are valuable LPBF features, but trapped powder creates safety, mass, contamination and inspection risks. Powder-removal strategy should be designed, documented and verified.

    • Provide adequately sized and correctly located escape holes.
    • Avoid blind cavities unless trapped powder is explicitly acceptable.
    • Use channel cross-sections that are both printable and cleanable.
    • Consider line-of-sight, gravity, vibration, vacuum and fluid-cleaning access.
    • Account for powder agglomeration after thermal exposure.
    • Verify residual powder using the method required by the application.

    For safety-critical hardware, “we shook the powder out” is not a controlled process. Cleaning acceptance criteria belong in the manufacturing plan.

    6. Add machining allowance intentionally

    LPBF rarely delivers every surface at final tolerance and finish. Critical bores, sealing faces, bearing seats, threads, datums and interfaces commonly require machining.

    A machining-ready design identifies:

    • Functional datums and how they will be established
    • Surfaces that require stock allowance
    • Workholding features and fixture access
    • Tool approach, reach and collision constraints
    • How the part will be located after support removal or heat treatment
    • Which features should be printed near-net-shape versus machined from solid stock

    Uniform extra stock is not always best. Allowance should reflect expected distortion, surface orientation, feature size and the planned machining sequence.

    7. Design for inspection

    Inspection access is a design variable. Complex internal passages may be impossible to evaluate using conventional line-of-sight methods. X-ray computed tomography can provide powerful volumetric inspection, but part size, material density, wall thickness, resolution and scan time limit what it can detect.

    Define critical-to-quality features and credible defect modes before selecting NDT. Inspection should be matched to the required probability of detection, not chosen simply because a technology is available.

    8. Use lattices and topology optimization selectively

    Topology optimization and lattices can reduce mass or tailor stiffness, heat transfer and energy absorption. They can also increase file size, build time, surface area, powder-removal difficulty and inspection burden.

    Before adopting an optimized geometry, ask whether it:

    • Creates a measurable system-level performance gain
    • Can be built across the qualified process window
    • Can be cleaned and inspected
    • Can be represented and transferred reliably in the digital workflow
    • Can tolerate expected process variation and surface condition
    • Still offers value after supports, machining and qualification are included

    9. Material selection is process-route selection

    A familiar alloy designation does not guarantee familiar properties. LPBF microstructure and performance depend on powder, parameters, orientation, heat treatment and post-processing. Select materials based on validated data for the intended route, not on wrought handbook values.

    The design allowable, coupon plan and acceptance criteria must reflect the actual production process. For regulated applications, changes to powder source, machine model, parameter set or thermal treatment may require formal review or requalification.

    10. Build a production checklist

    1. Define loads, environment, life, failure modes and acceptance requirements.
    2. Select a qualified machine–material–parameter–post-process route.
    3. Choose orientation using thermal, support, surface, cost and inspection objectives.
    4. Review overhangs, thin walls, holes, channels and recoater-sensitive features.
    5. Complete support, depowdering, cut-off, heat-treatment and machining plans.
    6. Define datums, stock allowances, fixtures and inspection access.
    7. Run simulation where it adds value and validate with representative hardware.
    8. Freeze the digital definition and control manufacturing changes.
    9. Use process monitoring and witness specimens only as part of a defined quality plan.
    10. Capture lessons from build, post-processing and inspection and feed them back into design rules.

    Conclusion

    The strongest LPBF designs integrate product function with manufacturing reality. Orientation, support, heat flow, powder removal, machining and inspection are not downstream details; they are core design inputs. The goal is a stable process route that repeatedly produces acceptable hardware, not a one-time successful print.

    Related Addithive resources: NDT for Additive Manufacturing · AM Surface Finishing

    References and further reading

    Continue the analysis

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    Companies to inspect: 3D Systems · Nikon · Materialise

    Track changes: AM Company Signals · Company Database

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