Inside3DPrinting_DavidBourell

Materials for 3D PrintingD.L. Bourell

Temple Foundation ProfessorThe University of Texas at Austin

Inside 3D Printing – San JoseSeptember 17, 2013

Material Demands for 3D Printing

• Form Proper Feedstock

• Fabricator Processability

• Post-Processability as Needed

• Acceptable Service Properties

Categories of 3DP Processes (ASTM F2792)

binder jetting, n—an additive manufacturing process in which a liquid bonding agent is selectively deposited to join powder materials.

directed energy deposition, n—an additive manufacturing process in which focused thermal energy is used to fuse materials by melting as they are being deposited.

material extrusion, n—an additive manufacturing process in which material is selectively dispensed through a nozzle or orifice.

material jetting, n—an additive manufacturing process in which droplets of build material are selectively deposited.

powder bed fusion, n—an additive manufacturing process in which thermal energy selectively fuses regions of a powder bed.

sheet lamination, n—an additive manufacturing process in which sheets of material are bonded to form an object.

vat photopolymerization, n—an additive manufacturing process in which liquid photopolymer in a vat is selectively cured by light-activated polymerization.

Materials in General, over 3000 “Common” Types

Plastics (Polymers)

WeakDeformable

Low Melting

StrongTough

High Melting

Wear ResistantBrittle

Very High Melting

Source: Edupack Software, Granta Designs, 2012

Metals Ceramics

Polymers in General

Thermoplastics

Melt Reversibly

Cross Link Irreversibly

Large Elastic Deformation

Various Web Sources

Thermosets Elastomers

Thermoplastics

Amorphous• Melts over a range of

temperature• “Pasty”• Good for Material

Extrusion (FDM)• ABS, PLA, PES

Various Web Sources

• Melts at a single temperature

• “Liquidy”• Good for LS• PA (nylon), PEEK

Crystalline

Materials for 3D Printing

“Roadmap for Additive Manufacturing: Identifying the Future of Freeform Processing”, D.L. Bourell, M.C. Leu, D.W. Rosen, eds, The University of Texas at Austin, 2009, 92 pages.

SL

LS, FDM SLM, EBM, DED

Material for Additive Manufacturing

• Composites• Binders

Transient Permanent

• Support Structures• Graded Structures• Multi-Materials

“Roadmap for Additive Manufacturing: Identifying the Future of Freeform Processing”, D.L. Bourell, M.C. Leu, D.W. Rosen, eds, The University of Texas at Austin, 2009, 92 pages.

Materials Grand Challenge in AM

• Quality• Process Consistency, Repeatability• Reliability• Wide Diversity of Compositions• Superior Structure and Properties• Low (Feedstock and Processing) Cost

Materials for Fused Deposition Modeling(Amorphous Thermoplastics)

• ABS [Acryonitrile Butadiene Styrene] $7-115/lb• Polycarbonate $113/lb• PC/ABS Blend• PLA [Polylactic Acid] $7-25/lb• Polyetherimide (PEI) [Stratasys ULTEM] $220/lb• Nylon Co-Polymer (new in 2012)

Source: 2012 Wohlers Report

Materials for Stereolithography and Material Jetting

(Proprietary Thermosets, ~$100/lb)

• Acrylics• Acrylates• Epoxies• “ABS-like” (Material Jetting)


Materials for Laser Sintering (Crystalline/Semi-Crystalline Thermoplastics)

• Polyamide (Nylon) 11 and 12 ~$40/lbNeatGlass FilledCarbon FilledMetal (Al) Filled

• Polystyrene (Lost Wax Patterns)• Polypropylene• Polyester (“Flex”)• Polyetheretherkeytone (PEEK)• Thermoplastic Polyurethane (new in 2012)• Nylon 6 (new in 2012)


Metals for AM (BJ, DED, PBF, SL)

• Tool Steel ~$50/lb• Stainless Steel ~$50/lb• Aluminum Alloys ~$50/lb• Co-Cr Alloys ~$55-250/lb• Nickel Alloys ~$95-125/lb• CP Titanium ~$150-400/lb• Ti-6Al-4V ~$150-400/lb• Gold• Silver


Most Popular:SLMEBMBJ (ExOne)

DED (LENS, POM, etc.)LOM (UAM)

• Common 3DP materials are generally not patent protected

• Material cost is high for consumers, but new suppliers do not seem to be entering the marketplace

• Perhaps the price will come down as material usage volume increases due to adoption

• My impression is that there is little consumer loyalty to a specific brand of material

Materials Perspectives

• Materials will be demanded in a quantity to justify volume production with concomitant reduction in unit cost for the user. Material cost will drop.

• Lower cost will increase usage, engendering greater demand,…

• Several “mini-suppliers” or niche product companies have appeared in the last 5-10 years and seem to be surviving.

Materials Forecast

Stress or Strength [Take a load without failing]

Ductility [Permanent elongation at failure]

Stiffness [Measure of springiness]

Fracture Toughness [Ultra-strong or ultra-brittle]

Fatigue [Elastic cyclic loading]

Mechanical Properties

StrengthStrength is an intrinsic term.

𝑆𝑇𝑅𝐸𝑁𝐺𝑇𝐻=𝑆𝑇𝑅𝐸𝑆𝑆=𝐹

𝐴𝑟𝑒𝑎

𝑆𝑇𝑅𝐸𝑆𝑆=500 𝑙𝑏𝑠

( 𝜋4 ) (0.08 𝑖𝑛)2=100,000 psi

1000𝑝𝑠𝑖=1kilo (𝑝𝑠𝑖¿=1𝑘𝑠𝑖

F

Bending is Not Tension!

F

F

F

L

Strength

F F =F

Strength

• Yield Strength – Stress to start permanent deformation

• Ultimate Strength – Stress needed to break the sample into two pieces

Strength

Metric Unit of stress is the “megapascal” MPa

1𝑀𝑃𝑎=106 𝑁𝑒𝑤𝑡𝑜𝑛𝑠𝑚2 =

17𝑘𝑠𝑖

<0.5 ksi A part “falls apart”

20 ksi Most Woods/Plastics

80 ksi Structural Steel/Aluminum

400 ksi High-Strength Steel

Strength

Strength

2012 Edupack Material Selector Software

3000 Commercial Materials

Summary of AM Mechanical Behavior

Metals Polymers Non-Metallics

Modulus of Elasticity

Porosity Driven(Power Law)

Porosity Driven(Power Law)

Porosity Driven

Strength/Ductility Porosity DrivenIsotropic (High )

Porosity DrivenAnisotropic (Ductility)

Porosity DrivenWeibull Works

Fatigue e<0.5UTS or no e -

Fracture Toughness

Less or equal to bulk -

1th

Processing Effects on Porosity in SLM Processed 17-4 Stainless Steel

A.B. Spierings, K. Wegener, G. Levy, “Designing Material Properties Locally with Additive Manufacturing Technology SLM”, Proc. SFF Symposium (2012), pp. 447-455.

Power = 190 WVscan = 1.30 m/sTlayer = 50 m

Power = 190 WVscan = 0.80 m/sTlayer = 30 m

Examples of Porosity in EBM Ti-6Al-4V

Khalid Rafi, H., Karthik N.V., Thomas L. Starr, Brent E. Stucker, “Defect formation in EBM parts built in horizontal orientation”, Proc. SFF Symposium (2012), pp. 456-467.

Khalid Rafi, H., Karthik N.V., Thomas L. Starr, Brent E. Stucker, “Defect formation in EBM parts built in horizontal orientation”, Proc. SFF Symposium (2012), pp. 456-467.

Examples of Porosity in EBM Ti-6Al-4V

Strength

J.P. Kruth, et al., “Binding Mechanisms in Selective Laser Sintering and Selective Laser Melting”, SFF Symposium Proceedings, Univ. Texas at Austin, 2004, pp. 44-58.

316L Stainless SteelSLM, As Processed

27.5 ksi

70-100 ksi

SLM 316 Metals

316L Stainless Steel (Stress Relieved)SLM Conventional

Yield Strength, ksi 92.8 45.0Ult. Strength, ksi 110 89.9Elongation, % 30 30

15-5 PH Stainless Steel (H900)SLM Conventional

Yield Strength, ksi 160 170Ult. Strength, ksi 213 190Elongation, % 15 10

unpublished results, Tom Starr, U. Louisville

SLM of Ti-6Al-4V

Table for AM Ti-6Al-4V (unpublished results, Tom Starr, U. Louisville)


C.E. Majewski and N. Hopkinson, “Effect of section thickness and build orientation on tensile properties andmaterial characteristics of Laser Sintered nylon-12 parts”, SFF Symposium Proceedings, Univ. Texas at Austin, 2010, pp. 422-34.

Nylon 12

200

400

600

0

Stiffn

ess

(ksi

)


S. Rüsenberg, L. Schmidt, and H.-J. Schmid, “Mechanical and Physical Properties – A Way to Assess Quality of Laser Sintered Parts”, SFF Symposium Proceedings, Univ. Texas at Austin, 2011, pp. 239-51.

Virgin PA2200 (Nylon 12) DIN EN ISO 527-1 Test Method

200

400

0

Stiffn

ess

(ksi

)

Strength and Ductility

R.S. Keicher, A.M. Christiansen and K.W. Wurth, “Electron Beam Melted (EBM) Co-Cr-Mo Alloy for Orthopaedic Implant Applications”, SFF Symposium Proceedings, Univ. Texas at Austin, 2009, pp. 428-36.

66Co-28Cr-6MoEBM, HIP, Homogenized

(ksi) (ksi)

D.K. Leigh, Harvest Technologies, priv. comm., 2011.

LS Bulk*Yield (MPa) 3280 8400Tensile (MPa) 7250 8850% Elongation 27 350

*CES Edupack Matl Selector, Version 7.0.0, Granta Ltd., 2011

Mechanical Behavior of LS Nylon

Strength

-0.12 -0.1 -0.08 -0.06 -0.04 -0.02 01.5

1.55

1.6

1.65

1.7

1.75

1.8

1.85

1.9

Log(D)

Log(

H)

E. Yasa, et al., “Microstructure and Mechanical Properties of Maraging Steel 300 after Selective Laser Melting”, SFF Symp., 2010, pp. 383-396

SLM Maraging Steel 18Ni300Various Layer Thicknesses

R.M. German, “Powder Metallurgy and Particulate Materials Processing”, MPIF, Princeton NJ, 2005, p. 385.

Strength

M.K. Agarwala, D.L. Bourell, B. Wu, J.J. Beaman, “An Evaluation of the Mechanical Behavior of Bronze-Ni Composites Produced by Selective Laser Sintering”, SFF Symposium Proceedings, H.L. Marcus, J.J. Beaman, J.W. Barlow, D.L. Bourell and R.H. Crawford, eds., Austin TX, 193-203 (1993).

Room-Temperature Tensile Strength of Pre-Mixed SLS (90Cu-10Sn) Bronze and Commercially Pure Nickel Powder as a Function of Relative Density = 1-. (a) As SLS Processed, (b) SLS Processed and Sintered at 900-1100C for 1 to 10 hr.

Mechanical Properties of AM Parts

Ductility

Relative Ductility as a Function of Fractional Porosity for Pure Iron. Various Particle Sizes and Purity. [From Haynes, Powder Met., 1977, 20, 17-20]

2/12

2/3

1

1

)0(

)0(

CDuctility

Ductility

Ductility

0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.450

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

Relative Porosity

Elon

gatio

n

LS Polyamide 12C = 4000

D.K. Leigh, D.L. Bourell, J.J. Beaman, “Basis for Decreased Mechanical Properties of Polyamide in Selective Laser Sintering” Proc. SFF Symposium, Austin TX, 2011.

R. Haynes, “A Study of the Effect of Porosity Content on the Ductility of Sintered Metals”, Powder Metallurgy 20 (1977) pp. 17-20.

SLM Ti-6Al-4V Based on Post-Process Anneals (Furnace Cooled)

Thöne, M., S. Leuders, A. Riemer, T. Tröster, H.A. Richard, “Influence of heat-treatment on Selective Laser Melting products – e.g. Ti6Al4V”, Solid Freeform Fabrication Proceedings, (2012), pp. 492-498.

Ti Ductility

Ti-6Al-4VSLM, As ProcessedCompared to Annealed and Solution Treated and Aged Ti64.

B. Vandenbroucke and J.P. Kruth, “Selective Laser Melting of Biocompatible Metals for Rapid Manufacturing of Medical Parts”, SFF Symposium Proceedings, Univ. Texas at Austin, 2006, pp. 148-159.

Aging Effects on Mechanical Properties of SL Polymer

Karina Puebla, Karina Arcaute, Rolando Quintana, Ryan B. Wicker, “Effects of environmental conditions, aging, and build orientations on the mechanical properties of ASTM type I specimens manufactured via stereolithography”, Rapid Prototyping Journal, 18#5 (2012), pp. 374–388.

ASTM Standards wrt Materials/Properties

Issued StandardsF2924-12 Standard Specification for Additive Manufacturing Titanium-6 Aluminum-4 Vanadium with Powder Bed FusionStandards Under DevelopmentWK27752 New Specification for Powder Bed Fusion of Plastic MaterialsWK33776 New Specification for Additive Manufacturing Nickel Alloy (UNS N07718) with Powder Bed Fusion WK33833 New Specification for Additive Manufacturing Cobalt-28 Chromium-6 Molybdenum with Powder Bed Fusion WK37654 New Practice for Machine Operation for Directed Energy Deposition of MetalsWK37658 New Specification for Additive Manufacturing Nickel Alloy (UNS N06625) with Powder Bed FusionWK37683 New Specification for Additive Manufacturing Titanium-6 Aluminum-4 Vanadium with Extra Low Interstitials with Powder Bed Fusion

Summary of AM Mechanical Behavior

• Mechanical behavior is predictable based on the traditional understanding of microstructure and processing.

• Porosity has a strong influence on the mechanical behavior.

• Anisotropy is not an issue if parts are built with low porosity and good layer interface.

• Polymers produced using best practice have isotropic strength and anisotropic ductility.

Overall Summary

• 3DP is hereto stay, and the market is developing explosively

• Materials for 3DP offers an opportunity for business venture

• Market timing is a factor for entry into 3DP materials• 3DP fabricators will continue to proliferate driven by

expiration of founding patents over the next 1-5 years• There is not much brand loyalty of materials among

users of 3DP materials

Mechanical Properties of RM Parts

Fatigue/Fracture

•Strongly Influenced by Residual Porosity

•Morphology Important - Pore Volume Fraction, Size, Spacing, Especially on the Surface

•Pores Generally Increase Threshold Stress Intensity for Crack Initiation

•Pores Generally Decrease the Resistance to Crack Propagation

•Fatigue Limits in Low-Porosity Materials are Generally 0.35(UTS) Compared to 0.5(UTS) for Fully Dense Materials

Fatigue

Reid, Fatigue of Fused Deposition Modeled (FDM) Acrylonitrile Butadiene Styrene (ABS) Stage Three individual Project MEC 3098, Newcastle University School of Mechanical and Systems Engineering 2011.

Fatigue of FDM Processed ABS polymer

Fatigue

P.A. Kobryn and S.L. Semiatin, “Mechanical Properties of Laser-Deposited Ti-6Al-4V”, SFF Symposium Proceedings, Univ. Texas at Austin, 2001, pp. 179-186.

LENS Processed Ti-6Al-4V, Stress Relieved or HIPped

Fracture Toughness

P.A. Kobryn and S.L. Semiatin, “Mechanical Properties of Laser-Deposited Ti-6Al-4V”, SFF Symposium Proceedings, Univ. Texas at Austin, 2001, pp. 179-186.

LENS Processed Ti-6Al-4V, Stress Relieved or HIPped

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