SLS Metal Powder: Properties,Applications,and Suppliers

Table of Contents

Selective laser sintering (SLS) is an additive manufacturing technique that uses a laser to fuse small particles of plastic, metal, ceramic or glass powders into a 3D object. SLS metal powders with the right characteristics are critical to fabricating high-quality metal parts with complex geometries via this process.

Overview of SLS Metal Powders

SLS metal powders refer to metallic powders that are optimized for use in selective laser sintering 3D printers to produce metal parts and prototypes. The most commonly used SLS metal powders include:

SLS Metal Powder Types

TypeCompositionKey Characteristics
Stainless steelFe, Cr, Ni alloysCorrosion resistance, high strength
Tool steelFe, Cr, Mo alloysHigh hardness, heat treatable
Alloy steelFe, Cr, Ni alloysHeat treatable, machinable
Cobalt-chromeCo, Cr alloysBiocompatible, wear/corrosion resistant
Titanium & alloysTi, Al, V alloysLightweight, biocompatible, strong
InconelNi, Cr alloysHeat/corrosion resistant
Aluminum alloysAl, Cu, Mg alloysLightweight, strong

These metal powders must have properties like flowability, particle shape and size distribution tailored to produce high density SLS parts with accuracy, precision and desired mechanical properties.

Key Properties of SLS Metal Powders

ParameterDescriptionRequirements
Size rangePowder particle dimensions10-45 microns common
Size distributionRange of powder sizesMostly spherical with some satellites allowed
MorphologyPowder particle shapeSpherical is optimal, satellites can cause defects
Flow ratePowder flowability35-40 s/50g from Hall flowmeter
Apparent densityPowder packing densityAround 60% of true density
True densityMaterial densityVaries by composition
Surface areaParticle surface area per unit massLower is better to reduce oxidation
Residual gases & moistureImpurities present with powderMinimized for high quality parts

SLS Metal Powder Characteristics

CharacteristicRole in SLS Process
Particle shape and surface textureAffect powder flow into each new layer, laser absorption, reflectivity
Particle size distributionImpacts packing density, melt pool dynamics, spreadability
Flow characteristicsAllows uniform spreadability, layer consistency
Apparent densityControls spacing between particles, energy input needed
True densityDetermines final maximum attainable part density
Alloying additionsEnables specific material properties like strength, hardness etc.
sls metal powder

Applications of SLS Metal Powders

SLS metal powder enables printing of full density functional metal parts serving prototyping, tooling and short run production needs across industries like:

Industry Applications of SLS Printed Metal Parts

IndustryApplicationsCommon Materials Used
AerospaceTurbine blades, engine/structural componentsStainless steels, superalloys, titanium alloys
AutomotivePrototype parts, custom toolingStainless steels, tool steels, aluminum alloys
Medical implantsPatient-specific implants, guidesCobalt chrome, titanium alloys, stainless steel
IndustrialPrecision tooling, robot grippersStainless steels, tool steels
JewelryRings, chains, custom piecesPrecious metals like gold alloys, silver

Some unique benefits versus traditional manufacturing routes:

Advantages of SLS for Metal Part Production

BenefitDescription
Geometry freedomNo part geometry restrictions unlike subtractive/casting methods
Quick turnaroundRapid printing from CAD data
Light weightingLattice structures reduce weight by >30%
Part consolidationIntegrally printed assemblies replace joints
Mass customizationPatient-specific medical devices
Hybrid structuresMetal & polymer multi-material parts possible

Common SLS printed metal part applications across industries:

Typical Applications of SLS Printed Metal Parts

ApplicationExamplesMaterials Used
Functional prototypesEngine components, implantsAlloy steels, Ti alloys
ToolsDrill guides, fixtures, jigsStainless steels
Mold toolingInjection molding toolingTool steels like H13
Series productionAerospace/medical componentsTi & Ni alloys, CoCr
Lightweight structuresLattice panels, bracesAl alloys, Ti alloys

SLS Metal Powder Specifications

SLS system manufacturers like EOS, 3D Systems, and Renishaw provide qualified SLS metal powder specifications tailored for their printer models. Some common metal powders and sizes include:

SLS Metal Powder Types and Size Ranges

MaterialPowder Types AvailableParticle Size Range
Stainless steel316L, 17-4PH, 303, 41015-45 microns
Maraging steelMS1, 18Ni300, 18Ni35015-45 microns
Cobalt chromeCoCr, CoCrMo15-45 microns
Aluminum alloyAlSi10Mg, AlSi1215-45 microns
Titanium alloyTi6Al4V Grade 515-45 microns
Nickel alloyInconel 718, Inconel 62515-45 microns

Standards organizations have defined classifications for different metal powder grades used in AM processes:

Metal Powder Grades per ISO/ASTM Standards

StandardGradesDescription
ISO 17296-2PA1 to PA6Defines increasingly stricter requirements on impurities from P1 to P6
ISO 17296-3PM1 to PM4Defines particle shape, size parameters from PM1 to PM4
ASTM F3049Class 1 to Class 4Defines allowable limits on composition ranges from 1 to 4
ASTM F3056Type 1 to Type 3Defines statistical size distribution parameters from 1 to 3

These grading schemes help set benchmark quality levels and aid buyers in procurement. High purity PA5 grade powder would ensure minimal contamination. Similarly Class 4 tighter chemistry control reduces variability.

SLS Metal Powder Suppliers

A variety of vendors supply ready-to-use SLS powders worldwide. Some leading global suppliers are:

Key SLS Metal Powder Suppliers

SupplierMaterials OfferedGeographies Served
SandvikStainless steel, Ni alloys, CoCr, tool steel, aluminum alloysEurope, Asia
PraxairTi alloys, Ni alloys, stainless, tool steelsNorth America
LPW TechnologyStainless steel, aluminum alloys, CoCrUK, Europe
Carpenter AdditiveStainless steels, CoCr, Cu, aluminum alloysGlobal
HoganasStainless steels, tool steelsEurope, Asia

Usual supply minimums are around 10 kg per material grade, though large volume contracts also exist for OEM buyers. Packaging options range from vacuum sealed cans to specialized SLS machine cartridges holding 700 g to 1 kg powder each.

SLS Metal Powder Packaging Types

TypeVolume RangesCharacteristics
Vacuum cans500g to 20kg batchesShelf life up to 1 year
Printer cartridges700 to 1000g batchesMinimized handling exposure
Material towers700 to 1200g cartridgesAutomated feed into printer

Price ranges for common materials in small quantities are:

Metal Powder Cost Ranges for SLS Printing

MaterialSmall Quantity Price Range*
Stainless steel 316L$60-$100 per kg
Aluminum AlSi10Mg$80-$130 per kg
Maraging steel$90-$140 per kg
Titanium Ti6Al4V$200-$350 per kg
Cobalt chrome$300-$500 per kg
Precious metals$3000+ per kg

Comparing SLS Metal Powder Materials

Various metal alloys are used for SLS printing, each with their own properties and tradeoffs:

SLS Metal Powder Materials Comparison

ParameterStainless SteelsTool SteelsTitanium AlloysNickel AlloysCobalt ChromeAluminum Alloys
DensityMediumHigherLowerHighHighLowest
StrengthMediumHighestMedium-HighMedium-HighMediumMedium
HardnessLowerVery highMediumMediumHigherLow-Medium
Corrosion ResistanceExcellentMediumExcellentExcellentExcellentMedium-Good
Bio-compatibilityGoodLimitedExcellentLimitedExcellentGood
Heat ResistanceMediumMedium-HighMediumVery HighVery HighLower
CostLowestMediumHighVery HighHighLow

We can see stainless steels offer the best combinational properties when cost is a consideration, while tool steels provide extreme hardness. Titanium brings biocompatibility and strength with low density. Superalloys like Inconel and CoCr offer thermal stability and biocompatibility. Aluminum alloys are the most cost-effective lightweight option.

Pros and Cons of Common SLS Metal Powders

MaterialAdvantagesDisadvantages
Stainless steelsCost-effective, readily machinableLower hardness and strength
Tool steelsExtremely hard and heat treatableLess corrosion resistance, biocompatibility
Titanium alloysStrong, lightweight, bio-friendlyExpensive, can burn in oxygen atmosphere
Nickel alloysExcellent heat/corrosion resistanceHeavy, toxic, very expensive
Cobalt chromeBiocompatible, corrosion resistantHeavy, medium cost
Aluminum alloysLightweight, good strengthLower melting point, hardness

Customer Criteria for Selecting SLS Metal Powder

Selection CriteriaKey Questions
Mechanical propertiesDoes it meet target application strength, wear resistance and other mechanical specifications?
Material costDoes desired metal powder type fit application budgets?
Post-processingAre secondary operations like Hot Isostatic Pressing or heat treatment needed?
Production run sizeIs target volume too high for production SLS printing?
Part size dimensionsIs maximum printer build volume sufficient for largest part geometries?
Resolution, surface finishCan SLS process achieve fine-feature-detail and surface quality requirements?
Delivery lead timeIs supplier lead time acceptable considering production timeline?

The end part application guides optimal material selection balancing performance needs and economics.

SLS Metal Printing Process Overview

Understanding SLS 3D printing helps appreciate how powder properties affect part quality:

SLS 3D Printing Process Stages

StageDescription
3D ModelingCAD software creates solid/mesh model of part to print
SlicingModel is digitally sliced into layers to generate printer file
Powder spreadingRoller or blade spreads thin layer of powder on build platform
Laser scanningCO2 laser scans over powder bed to melt particles together
Lowering platformBuild platform lowers by 1 layer thickness (~50 microns)
Repeat spreading/meltingSteps repeat until full object is built up layer-by-layer
Post-processingExcess powder removed, final treatments done to finish part

How Powder Characteristics Impact Print Results

Powder PropertyInfluence on Print Quality
Powder geometrySpherical particles with good flow enable uniform layers without defects
Particle size rangeToo fine powders have poor flow, too large creates poor resolution
Size distributionToo wide a distribution can segregate or create variable melting
Apparent densityHigher density yields greater final part density after sintering
True densityPlaces upper limit on achievable part density
Surface textureRougher particles can trap gases or hamper powder flow

We can see several powder physical properties directly impact print results, so tight control by suppliers is crucial.

Post-Processing of SLS Printed Metal Parts

After the SLS printing process, additional finishing steps help improve final part properties:

Common SLS Part Post-Processing Steps

ProcessDescriptionBenefits
Powder removalExcess powder brushed/blasted offReveals printed object
Stress relievingHeating to remove residual stressesImproves dimensional accuracy
Surface finishingSanding, polishing, bead blastingSmoothens surface, aids coating adhesion
InfiltrationLiquid fills residual porosityFurther increases density, improves strength
Heat treatmentHardening and tempering thermal cyclesEnhances hardness in steels

Post-Processing Effects on Part Properties

PropertyPost-Processing Influence
DensityInfiltration with epoxy or bronze fills pores increasing density 5-15%
Surface roughnessManual/automated polishing can achieve under 2 micron roughness
Dimensional accuracyStress relieving heat cycle reduces warpage improving precision
Tensile strengthInfiltration improves UTS while heat treatment can double yields strength
DuctilityTradeoff with strength improvement from post-treatments
HardnessPrecipitation hardenable alloys like 17-4PH respond well to aging treatments

Thus post-processing allows tailoring metal properties further based on application needs.

SLS Metal Printing Quality Control

Consistent high quality powder feedstock coupled with SLS process monitoring ensures reliable parts:

Quality Control for SLS Metal Powder

ParameterTypical SpecificationTest Methods
Particle size distributionHall flow rate > 35s/50gSieving, laser diffraction
Apparent density65-80% of true densityGravimetric measurement
Powder compositionAlloying ranges per ISO 27296X-Ray fluorescence
Surface morphologyMedian circularity > 0.75Micrographs, image analysis
Contamination< 50 ppm oxygen, < 150 ppm nitrogenInert gas fusion analysis

In-Process Monitoring for SLS Printing

MetricSensor UsedPurpose
Laser powerBuilt-in photodiodeMaintains fusion consistency
Powder bed tempIR sensorEnsures part integrity, no warping
AtmosphereOxygen analyzerAvoids powder ignition in build chamber
Layer thicknessZ-axis encoderPrecise reproducible layers

Such stringent control over input powder and process settings results in high quality metal parts from each production run.

SLS Metal Printing Compared to Alternatives

Other metal 3D printing alternatives to SLS include:

Comparison of Metal 3D Printing Methods

MetricBinder JettingDMLSSLMEBM
Raw materialMetal/polymer mix powderMetal powderMetal powderMetal wire/powder
Energy sourceLiquid binderFiber laserPowerful Yb fiber laserElectron beam
Build speedModerate, faster than laser methodsSlow due to point-by-point scanningVery fast, full melting occursFastest method
Resolution, surface finishPoorer due to binder, post-processing helpsVery good due to fine laser spotExcellent due to full meltingModerate due to partial melting
Dimensional accuracy+/- 0.3% with CTQ process+/- 0.1-0.2%+/- 0.1-0.2%+/- 0.2-0.3%
Post-processingCuring, sintering both neededOnly support removalSome machining may be neededMost secondary work needed
Cost per partLower material cost helps reduce priceMuch higher operating costHigh equipment, material costHigh equipment cost

Among all methods, binder jetting has emerged as most cost-effective for metal part production at lower volumes up to 10,000 units. SLS provides the easiest post-processing combined with good accuracy and surface finish.

sls metal powder

FAQs

What industries use SLS metal printing?

SLS metal printing is used in aerospace, automotive, medical, and many other industries where precision metal parts are required.

What is the accuracy and resolution of SLS metal printing?

The accuracy and resolution depend on several factors, including the machine, material, and process parameters, but SLS metal printing can achieve high levels of precision.

Is post-processing required for SLS metal-printed parts?

Yes, post-processing may be required to remove support structures, improve surface finish, and meet specific requirements for the application.

What are the limitations of SLS metal printing?

Some limitations include the cost of equipment, limited size of build chambers, and the need for proper safety measures due to the use of lasers and metal powders.

Can SLS metal printing be used for mass production?

Yes, SLS metal printing can be used for both prototyping and low to medium-volume production of metal parts.

Is SLS metal printing environmentally friendly?

While it can reduce material waste compared to traditional manufacturing methods, the disposal of metal powders and energy consumption are factors to consider regarding its environmental impact.

Are there any safety precautions when working with SLS metal printing?

Yes, safety measures should be taken when handling metal powders, and operators should be trained to work with laser-based systems safely.

What is the cost of SLS metal printing services?

The cost varies depending on factors such as material choice, part complexity, and quantity. It’s best to request quotes from service providers for specific projects.

know more 3D printing processes

Share On

Facebook
Twitter
LinkedIn
WhatsApp
Email

MET3DP Technology Co., LTD is a leading provider of additive manufacturing solutions headquartered in Qingdao, China. Our company specializes in 3D printing equipment and high-performance metal powders for industrial applications.

Inquiry to get best price and customized Solution for your business!

Related Articles

Get Metal3DP's
Product Brochure

Get The Latest Products & Price List