3D Printing: Can It Work for Lighting?

2019 Annual Conference August 8 -10 | Omni Louisville Hotel | Louisville, KY

3D Printing: Can it work for lighting?

Nadarajah Narendran, PhD Professor/Director of Research, Lighting Research Center, Rensselaer Polytechnic Institute, Troy, NY

Indika U. Perera, PhD Research Scientist, Lighting Research Center, Rensselaer Polytechnic Institute, Troy, NY

1 ies.org/ac 3D Printing: Can it work for lighting?

LearningLearning Objectives Objectives

ParticipantsParticipants will willbe able be to: able to: 1. Compare the 3D printing processes available today. 1.2. Identify…………… Identify what fixture components can be made with today’s print 2. Compare……………….technologies. 3. Analyze the performance of 3D-printed components compared to the 3. Describe……………performance of components made using traditional methods. 4.4. Analyze……………. Describe the impact of 3D printing on businesses.

2 ies.org/ac IES presentation outline

This presentation will cover the state-of-the-art of 3D printing for lighting, including recent research on the ability of current print materials, 3D printers, and different additive manufacturing methods to create the optical, thermal, and electrical components required by lighting systems. The presenters will share results from laboratory studies conducted at Rensselaer’s Lighting Research Center on the use of 3D printing to create lighting components. In addition, the presentation will discuss the impact 3D printing will have on business.

3 ies.org/ac Press

3D PRINTING: CAN IT WORK FOR LIGHTING?

4 ies.org/ac What is 3D printing?

• 3D printing is a process by which 3D objects are formed by the addition of materials, one layer at a time.

– This process is also known as additive manufacturing (AM)

– Material is deposited via a printhead or a nozzle or other types of AM processes

Reference: 1. Excell, Jon. "The rise of additive manufacturing". The Engineer. Retrieved 2013‐10‐30. 2. https://en.wikipedia.org/wiki/3D_printing

5 http://edition.cnn.com/TECH/specials/make‐create‐ ies.org/ac innovate/3d‐printing/ 3D printing processes

• ASTM F2792-12a, ISO 17296-1 classify – Powder bed fusion (PBF) 7 distinct processes • Electron beam melting (EBM) • Selective laser sintering (SLS) – Vat photopolymerization (VP) • Selective heat sintering (SHS) • Stereolithographic (SLA) • Direct metal laser sintering (DMLS) • Digital light processing (DLP) • Multi-jet Fusion (MJF) – Material extrusion (MX) – Binder jetting (BJ) • Fused deposition modeling (FDM) • Powder bed and inkjet head 3D printing (PBIH) • Fused filament fabrication (FFF) • Plaster-based 3D printing (PP) • Continuous fiber fabrication (CFF) – Material jetting (MJ) – Sheet lamination • Multi-jet modeling (MJM) • Ultrasonic consolidation (UC) • Drop-on-Demand (DoD) • Laminated object manufacturing (LOM) – Direct energy deposition (DED) • Laser metal deposition (LMD)

6 ies.org/ac 3D printing processes and material

Polymer Metal Powder bed fusion Sheet lamination Direct energy Material jetting deposition Vat photopolymerization Material extrusion Binder jetting

Ceramic

http://www.3ders.org/articles/20170524‐sculpteos‐newly‐released‐state‐of‐3d‐printing‐2017‐report‐shows‐a‐maturing‐market.html Source: Adopted from IDTechEx 2018, Masterclass 7 handouts

7 ies.org/ac Rapid adoption of 3D printing by many industries

3D Printing Is Already 3D printing contribution by industry 3D printing technology shakes up parts Changing Health Care production for automakers

3D‐printed hearing aid (Image source: forbes.com)

3D‐printed parts for the Rolls‐Royce Phantom. (Image source: bmw.com)

3D Printing to Unlock Consumer Personalization Aerospace giant embraces 3D printing Source: Wohlers Associates, 2014 for flight‐ready parts

CFM International’s 3D‐printed fuel nozzle reduces part count Adidas Plans To Bring 3D Customizable 3D‐printed from 18 to just 1. (Image Printing To The Masses electric shavers (Image source: ge.com)/ https://www.forbes.com/ source: 3dprint.com)

8 ies.org/ac Why 3D printing for lighting?

Problem: Price erosion and quality of fixtures – LEDs are becoming a commodity item – Majority of LED light fixture manufacturing has moved overseas – LED lighting fixture prices are rapidly decreasing and US manufacturers are looking at ways to reduce manufacturing cost while not compromising quality

Potential solution: 3D printing; Mass customization rather than Mass production • Value proposition – Custom fixtures that better match with the built environments improves visual appeal and functions • Reduced cost custom fixtures – Reduced carbon footprint, manufactured close to construction site – Reduced manufacturing cost by reducing integration steps – Reduced storage • Rapid fixture design change – Easy to change fixture design On‐site, on‐demand manufacturing of cost competitive custom light fixtures 9 ies.org/ac Opportunity Vision: Change Architectural Lighting Practice

Building design Construction Interior finishing

Interior lighting with On-site 3D printing Custom lighting custom fixtures of fixture fixture design

10 ies.org/ac 3D printing can change the supply chain for LED light fixture

Manufacture Storage Transport Shipping Storage Transport Architecture

Current

Product manufacturing Present Product Design & Specification

Mass Production to Mass Storage Transport Architecture Customization With Additive Manufacturing

Impact Product • Increase local manufacturing and jobs design and • Reduced carbon footprint Manufacture • Better quality, custom light fixtures On‐site 11 Future ies.org/ac 3D printed light fixtures

• Some manufacturers are already marketing 3D printed light fixtures – Mostly decorative fixtures

https://lucept.com/2019/05/21/signifys‐3d‐ printed‐mycreation‐series/ https://www.designboom.com/design/gantri‐3d‐printing‐ https://all3dp.com/1/3d‐printed‐ 3DPrinting.Lighting_Philips Lighting bring‐designer‐lights‐life‐11‐02‐2017/ lamp‐lampshades‐3d‐printed‐light/ Telecaster_decodownlight_illuminated

12 ies.org/ac Market size for 3D printing and lighting fixture industries

• 3D printing industry expected to grow above $21 billion by 2020. • Lighting fixture market expected to grow above $35 billion by 2020.

https://www.computerworld.com/article/3066862/emerging‐technology/3d‐ printing‐industry‐to‐triple‐in‐four‐years‐to‐21b.html

13 ies.org/ac 3D Printing: Can it work for lighting?

14 ies.org/ac Understanding the needs for printing light fixtures

• Feasibility assessment Light Fixture – To investigate if functional lighting fixture components can be fabricated using current 3D printing technologies and materials: • Thermomechanical • Electrical • Optical

15 ies.org/ac Mechanical Components

16 ies.org/ac Potential 3D printing processes

• Mechanical and Electrical components Processes Technologies Materials Claimed advantages Claimed disadvantages Material extrusion FDM/FFF/CFF Thermoplastics, Stronger build parts Poor surface finish and composites, compared to SLA, DLP, slower build time compared; nanoparticle filler and MJM require support structure; polymers post processing

• Optical components Processes Technologies Materials Claimed advantages Claimed disadvantages Vat polymerization SLA, DLP Liquid Complex and detailed Post-processing; require photopolymer, geometry compared to support structure; limited composites FDM material

Source: https://dupress.deloitte.com/dup‐us‐en/focus/3d‐opportunity/the‐3d‐opportunity‐primer‐the‐basics‐of‐additive‐manufacturing.html and http://www.lboro.ac.uk/research/amrg/about/

17 ies.org/ac 3D printing processes

Material extrusion • Material is selectively dispensed through a nozzle

Source: – Fused filament fabrication (FFF) http://www.lboro.ac.uk/research/amrg/ab out/the7categoriesofadditivemanufacturin • Thermoplastic material through heated extruder g/materialextrusion// • Also called fused deposition modeling (FDM®) Vat photopolymerization • Produce parts from photopolymer material in a liquid state cured using either: – Stereolithography (SLA) • Selectively cure material using lasers – Digital light processing (DLP) • Cure photopolymer material using digital light projectors

Source: Wallace et al., “Validating continuous digital light processing (cDLP) additive manufacturing accuracy and tissue engineering utility of a dye‐initiator package,” Biofabrication, 2014, 6, 015003

18 ies.org/ac Typical 3D printing process workflow

• CAD design (3D model)

• Generation of *.stl or other compatible file

• Slicing of 3D model geometry

• Printing

• Post-processing/finishing

Source: https://technorphosis.files.wordpress.com/2014/04/3d‐printing‐process.jpg

19 ies.org/ac Heatsinks

• Metal heat sinks are commonly used in LED systems to keep LED junction temperatures low for optimum performance – Drawbacks: • Heavy • Expensive • Overdesigned thermal management

• Study objective: – To investigate if custom heat sinks of suitable thermal properties can be printed using the fused filament fabrication (FFF) method • LED junction temperature below 85°C

20 ies.org/ac Printed heatsinks 100% 9% • A significant portion of an LED 11% 15% 15% 80% 14% lighting product cost is for heat sink 16%

– DoE SSL roadmap, R & D plan Sep. 14% 19%

2017. 60% 7% 20% 4%

5% 40% • 3D printed metal or composite heat 41% 45% 26% sinks have the potential to Share of total cost 20% – Reduce weight and cost 18% 13% – Optimize thermal management 8% 0% – Produce visually appealing heatsinks Outdoor area Interior Replacement fixture downlight lamp

LED package Mechanical/Thermal/Electrical Optics Driver Assembly Overhead

Comparison of Cost Breakdown for Different Stonecipher and Alvarez (Aug. 2014) LEDs magazine webinar, Lighting Applications Source: DOE SSL Roundtable and Workshop https://www.prolighting.com/bxspr-a-0-3- attendees and industrial partners Solid‐State m-g-u- s.html?utm_source=google_shopping&utm_ DoE SSL roadmap: R & D plan Sep. 2017 Lighting; R&D Plan; Sept. 2017 source=google&utm_medium=cpc&adpos= 1o5&scid=scplpBXSPR-A-0-3-M-G-U- https://hdsupplysolutions.com/shop/Produ http://www.e-conolight.com/creer-lr6- S&sc_intid=BXSPR-A-0-3-M-G-U- series-6-deep-recess-led-downlight- ctDisplay?catalogId=10054&langId=- S&gclid=EAIaIQobChMI5cHahYCQ2gIVSuDI 2700k-50w-equivalent.html 1&partNumber=P701144&rr_cid=701144 21 Ch02YghnEAkYBSABEgJcRfD_BwE &storeId=10051 ies.org/ac Tailored thermal properties of PLA heatsinks

• In this study, we investigated how composite polylactic acid (PLA) filaments with thermally conductive fillers affect thermal conductivity of printed heat sinks to manage

the junction temperature, Tj, of the LED.

22 ies.org/ac Fabrication of heat sink

Printing orientation and print layer height affect heat sink performance

Print orientation Print layer height 4 120% y = 1.5541x R² = 0.9983 100% 3 C/mm]

° 80% [ ℓ T/

Δ 2 60%

40% 1 20% Cross-plane Relative thermal conductivity 0 0% 01234 0.0 0.5 1.0 1.5 2.0 2.5 Layer height [mm] In-plane ΔT/ℓ [°C/mm]

Plotted with source data from Perera et al., Optical Engineering 2018 Source: Olivia Privitera, Master’s project 2018 23 ies.org/ac Estimating Tj of LED with heat sink

LED heat sinkܳሶ

LED package

Parameter Value Thermal power of LED package (ܳሶ ) 1 ,2, 5, and 10 W

LED package thermal resistance (ܴ௣) 10°C/W

Diameter of LED package (ܦ௣ሻ 12.7 mm Heat sink length (ܮ) 10.0 cm Heat sink width (ܹ) 10.0 cm Heat sink thickness (ݐ)2.5 mm Heat sink surface emissivity (ߝ)0.9

Ambient temperature (ܶ௔௠௕ሻ 20°C

Thermal conductivity of aluminum ~200 W m-1 K-1 24 ies.org/ac Estimated Tj with different material heat sinks LED source energized at 2 W electrical power

2016

39°C

8°C

2018 34.11 mm

28.05 mm 27.8 mm

25 ies.org/ac Estimated and measured LED Tj for different material heat sinks

Simulation result at 1 W thermal power

34.11 mm

28.05 mm 26 27.8 mm ies.org/ac Predicting LED Tj at different LED power

41.9°C

22.9°C

34.11 mm 34.11 mm

28.05 mm 28.05 mm 41.7 mm 27.8 mm

27 ies.org/ac Summary

• Materials tested had effective κ-values ranging 0.0012 from ~0.3 to ~10 W m-1 K-1 600 lm/10 W 0.001 • The 3D-printable composite thermoplastic materials with κ-values ~10 W m-1 K-1 exhibited less than a 10°C increase compared to an 0.0008 extruded aluminum straight fin heat sink 1500 lm/16 W – Still ~2-4 times lower in κ-value required for most 0.0006 SSL heat sink applications

– Metal 3D-printing material is available for [W/mm²] 3000 lm/20 W comparable results to aluminum heat sinks 0.0004

240 lm/2W • Thermal conductivity of available materials 0.0002 1300 lm/18W adequate for low- to mid-power applications Heat sink electrical power density Heat sink electrical power wit low heat densities 0 MR 16 A-lamp A-lamp 6-in tested downlight straight fin heat sink

28 ies.org/ac Electrical Components

29 ies.org/ac Objective

• Electrical traces are commonly used to conduct current within the lighting system

• Study objective: – To investigate if electrical traces can be printed with suitable electrical properties

30 30 ies.org/ac Electrical properties of printed conductive traces Current • In this study we investigated electrical resistivity of A channel the 3D-printed conductive traces with three types of materials and print orientations: – Graphene infused PLA V 3‐D – Carbon nanotube based PLA Voltage printed channel – Conductive carbon black based PLA trace

• Results: – Graphene infused PLA showed the lowest resistivity (6.1 x10-3 Ωm) of all three materials, but it is much higher than copper traces (1.7 x10-8 Ωm) commonly used in PCB applications. – In-plane build orientation showed the lowest resistivity (70-80% lower compared to cross-plane)

31 ies.org/ac Summary

• There are commercial inks with resistivity values similar to copper. – But they cannot be processed using unmodified FFF-type 3D printers. • Requires paste extruder attachments to benefit from these highly conductive materials

https://support.voxel8.co/hc/en‐us/articles/208004096‐Working‐ with‐the‐Conductive‐Silver‐Ink‐Solvent • For example, Yu et al., recently reported a method where 3D-printed hollow channels within elastomer structures were filled with injected liquid metal to form electrical traces.

Yong‐Ze Yu, Jin‐Rong Lu, Jing Liua; 3D printing for functional electronics by injection and package of liquid Yong‐Ze Yu et al., 2017 metals into channels of mechanical structures, Materials and Design 122 (2017).

32 ies.org/ac Optical Components

33 ies.org/ac Optics

• LED light fixtures require secondary optics – For beam shaping • Typically, optical components are either reflective or transmissive type. • Properties of the optical component affect fixture efficiency and beam quality.

• Study objectives – To understand how short-term and long-term optical properties are affected when using 3D- printed optical components – To understand light transmission and scattering properties as a function of print resolution and print orientation – To understand reflected and transmitted light as a function of time

Olivia Privitera, Yi‐wei Liu, Indika U. Perera, Jean Paul Freyssinier, Nadarajah Narendran, "Optical properties of 3D printed reflective and transmissive components for use in LED lighting fixture applications," Proc. SPIE 10940, Light‐Emitting Devices, Materials, and Applications, 109401X (2 April 2019); doi: 10.1117/12.2510063 Event: SPIE OPTO, 2019, San Francisco, California, United States

34 ies.org/ac 3D printed reflective optics

• Materials used: – Reflective polylactic acid (PLA) - 2 types – Copolyester with no styrene (CoP) – single type

Printing parameters of the reflective samples • Samples using fused filament fabrication (FFF). – For each of the three materials, nine samples were printed in different thicknesses by varying the extrusion width or the number of extrusions.

The integrating sphere setup used to measure the total reflectance and spectral reflectance of the samples. Olivia Privitera, Yi‐wei Liu, Indika U. Perera, Jean Paul Freyssinier, Nadarajah Narendran, "Optical properties of 3D printed reflective and transmissive components for use in LED lighting fixture applications," Proc. SPIE 10940, Light‐Emitting Devices, Materials, and Applications, 109401X (2 April 2019); doi: 10.1117/12.2510063 Event: SPIE OPTO, 2019, San Francisco, California, United States 35 ies.org/ac Short-term performance results

• Reflectance properties of 3D printed samples. – Reflectance increased as sample thickness increased • Up to approximately 2-mm • Constant beyond 2 mm (80%, 90%, 92%)

– Spectral reflectance is different for different materials

• Reflectance properties of 3D printed samples as a function of time exposed to an ambient temperature of 50°C – Reflectance remained nearly constant over time • No degradation observed during the test period

37 ies.org/ac 3D Printed transmissive optics Before After polishing • Objective polishing – To understand light transmission and scattering 50 m properties as a function of print resolution and print orientation • Test samples 250 m – Print resolutions (50 μm and 250 μm) – Print orientation: in-plane and cross-plane laser • Results: – Polishing improved performance – Both print resolution and print orientation affect In‐plane light transmission and scattering laser • Increased print resolution 250 μm to 50 μm and in- plane print orientation, increased light transmission and decreased light scattering Cross‐plane Narendran, N., Perera, I.U., Mou, X., and Thotagamuwa, D.R., “Opportunities and challenges for 3‐D printing of solid‐state lighting systems,” Proceedings of SPIE 10378, 16th International Conference on Solid State Lighting and LED‐based Illumination Systems, SPIE Optics + Photonics, San Diego, Calif., August 2017, Paper 10378‐35 (2017).

38 ies.org/ac Printed transmissive optics: long-term performance

• Results – Transmissivity decreases by approximately 1.5% per mm in thickness – The SLA resin tested showed a systematic reduction in transmittance in the 400 nm to 500 nm region when exposed to 50°C. • Can result in undesirable color shift.

Relative change in spectral transmittance (left); and average transmissivity (right) as a function of time when exposed to an ambient temperature of 50 deg. C.

• Objective: To develop a novel optic and Thin planar optic investigate its potential for 3D printing Light source – Example: A rectangular transparent optic • Difficult to manufacture using traditional methods like injection molding but can be easily made Planar optic using 3D printing techniques with cavities – Planar surfaces with internal refractive structures

• Output beam shape depends on the cavity size, spacing, shape, etc., and light source(s) location(s). Beam distribution

40 ies.org/ac Tailored beam with planar optic with internal cavities (simulation)

10 mm 10 mm

R=15 mm

LED source – 205 lumens Wide beam Parameter Spherical Hemi‐ Narrow beam cavity spherical bumps Total flux output [lm] 113 110 Efficiency 0.55 0.53 Max. intensity [cd] 29 1179 FWHM [deg.] 150 6

41 ies.org/ac Tailored beam with planar optic (simulation)

Different beam distributions can be created by changing the internal cavity geometry and size

90° 90° 45° 45°

0° 0°

42 ies.org/ac 3D printed optic with 1 mm hemi-spherical dimples (Simulation) LED source – 205 lumens 10 mm Parameter Value Total flux output [lm] 160 R=1 mm Efficiency 0.78 Max. intensity [cd] 69

90° 45°

0°

43 ies.org/ac 3D printed optic with 1 mm hemi-spherical dimples

Simulation versus measured results

Optic designed by LRC and printed by Henkel

Simulated illuminance at 437 mm Measured illuminance at 457 mm

44 ies.org/ac 3D printed planar optic to produce uniform illuminance on the task plane (Measured results) By selecting proper dimensions and shapes for the internal cavities the beam distributions can be tailored Example: Uniform illuminance LED source – 150 lumens Measured Simulated ±300 mm ±402 mm ±300 mm ±402 mm square square square square Avg. E [lx] 136 99 138 120 Max. E [lx] 234 234 216 216 Min E [lx] 60 0 68 38 Max/Min 3.9 NA 3.2 5.6 Optic designed by Flux [lm] 52 66 53 79 LRC and printed by Efficiency 35% 44% 35% 53% Henkel

>200 Illuminance [lx] 45 ies.org/ac Summary - printed optics

• High performance (short and long term) reflective optics can be printed using presently available commercial materials. – Print thickness and orientation affects reflectance properties

• Better materials are needed for making reliable transmissive optics

• Novel optics that cannot be easily made using traditional manufacturing methods can be 3D printed – Greater benefits: Easy to clean, allows for easy integration in light fixtures.

46 ies.org/ac Final Remarks

47 ies.org/ac 3D Printing: Can it work for lighting?

• 3D printing offers new possibilities today – Today, visually pleasing functional components for light fixtures can be printed • Decorative lamp shades; Novel heat sinks suitable for low to mid watt LED lighting fixtures; Reflective optics with high reflectivity and longevity • Novel transmissive optics for tailoring beam patterns – However, cost is much higher today. • Improvements needed – New components designed for 3D printing – New materials for 3D printing – New printer technologies to make and assemble – Speed of manufacturing – Manufacturing cost 3D printing is poised to change the lighting industry and reverse the commoditization

Source: Olivia Privitera, IESNYC thesis prize presentation May 2018 48 ies.org/ac Acknowledgments

• IES Conference Committee • LRC faculty, staff and students Jean Paul Freyssinier, Yiwei Liu, Olivia Privitera, Valeria ASSIST Sponsors Terentyeva-Holland, Kasey Holland, Akila Udage, Sachintha 2016-2018 de Vas Gunawardena, Dinusha Thotagamuwa, Martin Acuity Brands Lighting Overington, Howard Ohlhous, Jennifer Taylor Amerlux BAE Systems • LRC internal funding Current by GE Crystal IS • ASSIST (2016-2018) Dow Corning • FAA contract # 16-G-019 (2016-2017) Eaton FAA Finelite Hubbell Lighting Future work at the LRC NYSERDA – Education OSRAM Opto Semiconductors – Industry consortium Philips – Funded projects Seoul Semiconductor US EPA

These projects were supported by above mentioned organizations and that such support does not constitute an endorsement by these organizations of the views expressed therein.

49 ies.org/ac 2019 Annual Conference August 8 -10 | Omni Louisville Hotel | Louisville, KY

Thank you

www.lrc.rpi.edu/programs/solidstate

50 ies.org/ac