SLM para la fabricación aditiva de metales

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Overview of Selective Laser Melting

Selective laser melting (SLM) is a powder bed fusion metal 3D printing process that uses a laser to selectively melt and fuse metallic powder particles layer-by-layer to build up fully dense parts.

Atributos clave de la tecnología SLM:

CaracterísticaDescripción
MaterialesMetals like stainless steel, titanium, aluminum, nickel alloys
Tipo láserFiber, CO2, or direct diode lasers
AtmósferaInert argon or nitrogen atmosphere
ResoluciónCapable of fine features down to 150 μm
PrecisiónParts within ±0.2% dimensions or better

SLM enables complex, customizable metal parts for aerospace, medical, automotive, and industrial applications.

Cómo funciona la fusión selectiva por láser

The SLM printing process works as follows:

  • 3D model sliced into 2D cross-section layers
  • Powder spread over build plate in thin layer
  • Laser selectively scans layer, melting powder
  • Melted powder solidifies and fuses together
  • Build plate lowers and new layer spread on top
  • Process repeats until full part built up

The unfused powder provides support while building up the component. This enables complex geometries without dedicated support structures.

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Types of Selective Laser Melting Systems

There are several SLM system configurations:

SistemaDetalles
Single laserOne high power laser for melting
Multi laserMultiple lasers to increase build speed
Scanning systemGalvo mirrors or fixed optics
Metal powder handlingOpen systems or closed powder recycling
Atmosphere controlSealed build chamber filled with argon or nitrogen

Multi-laser systems offer faster builds while closed-loop powder handling improves efficiency and recyclability.

Materials for Selective Laser Melting

Common metal materials used for SLM include:

MaterialBeneficios
Aleaciones de aluminioLightweight with good strength
Aleaciones de titanioElevada relación resistencia/peso
Aceros inoxidablesResistencia a la corrosión, alta tenacidad
Aceros para herramientasGran dureza y resistencia al desgaste
Aleaciones de níquelResistencia a altas temperaturas
Cobalto-CromoBiocompatible with good wear

A range of alloy powders enables properties like strength, hardness, temperature resistance, and biocompatibility needed across applications.

Applications of Selective Laser Melting

Typical applications of SLM metal printing include:

IndustriaAplicaciones
AeroespacialEngine components, lightweight structures
MédicoCustom implants, prosthetics, instruments
AutomociónPiezas ligeras, herramientas personalizadas
IndustrialLightweighting components, end-use production
Petróleo y gasCorrosion resistant valves, wellhead parts

SLM enables complex, custom metal parts consolidated into one piece and optimized for weight and performance.

Benefits of Selective Laser Melting

Key advantages of SLM technology:

BeneficioDescripción
Geometrías complejasUnlimited design freedom for organic shapes
Consolidación parcialAssemblies printed as one single component
PersonalizaciónEasily adapted to produce custom parts
AligeramientoEstructuras reticulares y optimización topológica.
Ahorro de materialReducción de residuos en comparación con los métodos sustractivos
Tratamiento posteriorMay require support removal and surface finishing

These advantages enable higher performing end-use metal parts at competitive lead times and costs at lower production volumes.

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Limitations of Selective Laser Melting

Limitations of SLM include:

LimitaciónDescripción
Tamaño de la piezaRestricted to printer build volume, typically under 1 m3
ProductividadRelatively slow production rates limit high volumes
Tratamiento posteriorMay require support removal, machining, finishing
AnisotropíaMechanical properties vary depending on build orientation
Acabado superficialAs-printed surface is relatively rough
Operator expertiseRequires extensive printer experience

The technology is best suited for low to medium production volumes of complex metal parts.

SLM Printer Suppliers

Leading SLM system manufacturers:

EmpresaNotable Systems
EOSSerie EOS M
Sistemas 3DDMP series
Aditivos GEX Line 2000R
trompetaTruPrint 1000, 3000
Soluciones SLMSLM 500, SLM 800
RenishawAM500, AM400

Machines range from smaller build volumes around 250 x 250 x 300 mm up to large 800 x 400 x 500 mm systems for high productivity.

Selecting an SLM 3D Printer

Key considerations when selecting an SLM system:

FactorPriority
Volumen de construcciónMatch to required part sizes
Supported materialsNeeded alloys like Ti, Al, stainless, tool steels
Sistema de gas inerteSealed, automated argon or nitrogen handling
Laser technologyFiber, CO2, or direct diode lasers
Scanning methodGalvo or fixed mirror scanning
Manipulación del polvoClosed-loop recycling preferred

The optimum SLM system provides the materials, build volume, speed, and powder handling features required for the applications.

SLM Facility Requirements

To operate an SLM printer, the facility must meet:

  • Electrical power levels 20-60 kW typical
  • Stable temperature around 20-25°C
  • Low humidity below 70% RH
  • Particulate control and metal powder handling
  • Inert gas supply and venting
  • Exhaust filtration for released particulates
  • Monitoring systems for atmosphere
  • Strong personnel safety procedures

SLM systems require substantial infrastructure for power, cooling, powder handling, and inert gas delivery.

SLM Printing Process Parameters

Typical SLM printing parameters:

ParámetroAlcance típico
Potencia del láser100-400 W
Velocidad de escaneo100-2000 mm/s
Grosor de la capa20-100 μm
Distancia entre escotillas50-200 μm
Tamaño del punto50-100 micras
Scanning patternAlternating, rotated for each layer

Precise adjustment of these parameters is required to achieve fully dense parts for each alloy powder.

SLM Directrices de diseño y limitaciones

Key SLM design guidelines include:

DirectrizRazón
Minimum wall thicknessAvoid heat buildup and warping
Supported overhangsPrevent collapse without supports
Avoid thin featuresPrevent melting or vaporization
Orientar para la fuerzaOptimize for load direction
Minimize support useSimplify post-processing

The SLM process imposes geometric requirements like overhang angles and minimum feature sizes that must be accounted for.

SLM Post-Processing Requirements

Common post-processing steps for SLM parts:

ProcesoPropósito
Eliminación de soportesRemove auto-generated supports from software
Eliminación de polvoClean remaining powder from internal passages
Acabado de superficiesImprove surface finish and roughness through machining
Alivio del estrésReduce residual stresses through heat treatment
Prensado isostático en calienteImprove density and reduce internal voids

The level of post-processing depends on the application requirements for tolerances, surface finishes, and material properties.

Qualification Testing for SLM Parts

Typical qualification tests for SLM components:

Tipo de pruebaDescripción
Análisis de densidadMeasure density compared to wrought materials
Pruebas mecánicasTensile, fatigue, fracture toughness tests
MetallographyMicrostructure imaging and defect analysis
Análisis químicosCheck composition matches specification
Non-destructiveCT scanning or X-ray inspection for voids

Thorough testing ensures SLM parts meet requirements before being put into production applications.

Beneficios de SLM Tecnología

Selective laser melting provides key advantages:

  • Complex, organic geometries not possible with casting or CNC
  • lighter weight structures through topology optimization
  • Part consolidation into single printed components
  • Reducción de residuos en comparación con los métodos sustractivos
  • Customization and rapid design iterations
  • Just-in-time production of metal parts
  • High strength and hardness approaching wrought materials

These benefits make SLM suitable for producing high value, low volume parts on-demand across industries.

Challenges of Adopting SLM Printing

Barriers to adoption of SLM include:

DesafíoEstrategias de mitigación
High printer costLeverage service bureaus, validate ROI
Opciones de materialNew alloys in development, specialty suppliers
Process knowledgeTraining programs, learning curve
NormasPart qualification protocols being developed
Tratamiento posteriorAutomated processes under development

As the technology matures, these barriers are being reduced through improved materials, equipment, training, and standardization efforts across the industry.

The Future of Selective Laser Melting

Emerging trends in SLM technology:

  • Larger build volumes above 500 x 500 x 500 mm
  • Multi-laser systems for faster build rates
  • Expanded alloys including high-temperature superalloys
  • Improved powder recyclability and handling
  • Eliminación automática de soportes y postprocesamiento
  • Hybrid manufacturing combining AM and CNC
  • Specialized software for design optimization
  • Standardization of process parameters and part qualification

SLM systems will continue advancing in terms of build size, speed, materials, and reliability to meet production needs across more industrial applications.

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Summary of Key Points

  • SLM selectively fuses metal powder with a laser for full density 3D printing
  • Powder bed fusion process capable of fine details and complex geometries
  • Suitable for aerospace, medical, automotive, and industrial applications
  • Uses metals like stainless steel, titanium, aluminum, and nickel alloys
  • Provides benefits of part consolidation, customization, lightweighting
  • Requires controlled atmosphere and robust powder handling systems
  • Significant post-processing may be needed on printed parts
  • Leading technology for low to medium volume production applications
  • Ongoing improvements in materials, build size, speed, and quality
  • Enables high performance printed metal components

Selective laser melting will continue growing as an industrial manufacturing solution for customized metal parts on-demand.

PREGUNTAS FRECUENTES

PreguntaRespuesta
What materials are compatible with SLM?Most weldable alloys like stainless steel, titanium, aluminum, tool steel, nickel alloys, and cobalt-chrome.
¿Cuál es la precisión típica de las piezas SLM?Dimensional accuracy around ±0.2% is achievable for most geometries.
¿Qué tratamiento posterior es necesario?Support removal, powder removal, surface finishing, stress relieving, and hot isostatic pressing are common.
What are common SLM defects?Porosity, cracking, layer delamination, warp, poor surface finish, unmelted particles.
What types of lasers are used in SLM?Fiber lasers, CO2 lasers, or high-power diodes are commonly used.

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MET3DP Technology Co., LTD es un proveedor líder de soluciones de fabricación aditiva con sede en Qingdao, China. Nuestra empresa está especializada en equipos de impresión 3D y polvos metálicos de alto rendimiento para aplicaciones industriales.

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