In the past 100 years, innovations in lighting have primarily involved new technologies for illumination. However, the manufacture of lighting fixtures over time has stayed relatively the same. Traditional manufacturing in many industries has started to be supplanted by a new innovation: 3D printing. While 3D printing is an opportunity to bring back lighting fixture manufacturing to the U.S., the few U.S. manufacturers remaining are not adopting it rapidly. To help the U.S. lighting industry, Rensselaer’s Lighting Research Center has conducted research, education, and collaborative activities to disseminate information and encourage the 3D printing of lighting. This paper provides an overview of LRC research regarding the potential for using 3D printing for the manufacture of lighting components and systems, as well as an explanation of the lessons learned and improvements needed to make 3D printing the first choice method for lighting manufacturing.

Merging developments in generative design, advanced configurability, and additive manufacturing technologies creates an opportunity to rapidly generate, visualize, and evaluate parametrically configured luminaire solutions. There is also the opportunity to be significantly more environmentally sustainable than conventional manufacturing while shortening product development timelines. Lighting designers spend a significant amount of time preparing designs for visual evaluation using a variety of software tools and CAD models to present options to a client and to the lighting manufacturer for approval. Generative design can create designs with user-controlled parameters to rapidly visualize a design tailored to a specific application. Error checking with the actual CAD can eliminate the need for manufacturer approval effectively making a “custom” solution standard. The generative design component is also seeded with randomness to generate designs that would never have otherwise been considered. This design tool has been developed and beta tested with select lighting designers to determine the next steps for optimizing workflows.

During the past several years, the interest for 3D printing of lighting optics has been growing rapidly. Most optical prototypes have been 3D printed using transparent photopolymer resin materials. However, the literature has limited information about the optical efficiency and the accuracy of beam shaping of such 3D-printed lenses. Therefore, to better understand the status of 3D printing lenses, a total internal reflection (TIR) lens was designed for use in replacement MR-16 (multifaceted-reflector) LED integral lamps. Several lenses were 3D printed in our laboratory and by two manufacturers. These 3D-printed samples were tested and the results were compared with a commercially available injection-molded TIR lens. The process and results of this benchmarking study are presented in this paper. The goal of this investigation was to study how 3D printer and material combination, build orientation, and post-processing affect the optical performance of LED lamps. The results showed differences in optical efficiency and beam shape for the printed samples. The highest optical efficiency achieved by these prototypes was 75%. The 3D-printed lenses with post-processing had similar performance to the injection-molded lens in terms of optical efficiency and beam width. The results showed that the layer height and print orientation affected the optical performance of the 3D-printed lenses. Our final conclusion is that 3D printing can achieve similar performance to commercially available polymer TIR lenses when suitable print parameters and postprocessing are selected. Further studies are needed to identify the best build orientation and print layer height to minimize the light scattering that affects the lens performance.

The state of research and technology in the field of Additive Manufacturing (AM) with Two-Photon Polymerization (TPP) focuses on stacking individually printed planar layers to create the desired geometries. As a result, benefits known from other Multi-Axis AM (MAAM) processes, such as printing on non-planar surfaces, are unexplored. Even though there’ve been endeavors in creating systems which go beyond the 2.5D approach, these lack the range of motion required to transfer many benefits of MAAM to the TPP process. This contribution provides a kinematic concept for a TPP MAAM system with at least three translatory and two rotatory degrees of freedom. To ensure the transferability of MAAM concepts to the TPP process, the system is required to provide a range of motion that is similar to that of existing MAAM systems. To limit the design complexity of the system, it is destined for the specific use case of printing aspheric micro optics. The presented concept details a blueprint for creating a five axis TPP kinematic print system, thereby providing a basis for the further advancement of TPP printing by enabling multi-axis curved layer printing.

Automated tools for the design of freeform illumination optics have enabled a new class of high-quality, high-efficiency luminaires for general lighting. Additive manufacturing takes this concept to the next level – allowing for completely custom luminaires to be designed and manufactured for very specific use cases. This paper looks at the optical designs created and manufactured for a Department of Energy project exploring the use of additive manufacturing for the lighting market. The subtle nuances of designing freeform optics for additive manufacturing as well as results of optical testing of material and surface quality will be discussed. Finally, comparisons will be provided between the simulated, as-designed optical performance and that of the measured parts.

Vat photopolymerization and multi-jet modeling 3D printers using clear polymer resins have shown promise for making optically clear lenses for LED lighting systems. These clear resins are usually polymethyl methacrylate, acrylonitrile butadiene styrene, and polycarbonate-like photopolymers. One of the main requirements for such lenses in LED lighting systems is stable performance, i.e., maintaining transmitted light and chromaticity for an extended period (over 25,000 hours). A long-term aging study was designed and conducted to understand light transmittance properties as a function of time. The 3D-printed lens samples were exposed to elevated ambient temperature (~45 and 60°C) and short-wavelength optical irradiance (~0.20 and 0.4 W/cm²) with peak wavelength radiation ~450 nm and FWHM ~25 nm. Test samples were 3D-printed using three clear transparent resins and using vat photopolymerization and multi-jet modeling processes. The lens samples were removed from the aging setup at regular intervals and the transmittance was measured at room temperature. The measured time to 90% lumen maintenance (L90) and 70% lumen maintenance (L70) were affected more by optical irradiance change from 0.20 W/cm² and 0.4 W/cm² than ambient temperature change from 45°C and 60°C. The vat photopolymerization 3D-printed test samples used for the study showed higher relative transmittance degradation than the multi-jet modeling test samples used in the study for both irradiances and ambient temperatures.

Automated tools for the design of freeform illumination optics have enabled a new class of high-quality, high-efficiency luminaires for general lighting; however, these tools are isolated to specialized software for the highly trained illumination engineer. There is a strong case to be made for an easy-to-use tool that can, for any given application space and lighting requirement, provide the ideal locations of luminaires as well as design the optics, electronics, and fixturing for each of those luminaires. If such a tool was available, there would potentially be fewer energy-impacting tradeoffs made when using off-the-shelf luminaires. This paper explores the work completed to date for a U.S. Department of Energy project that hopes to reduce overall energy impact of lighting by creating custom luminaires using additive manufacturing processes. The steps taken toward an automated luminaire layout and optical design software solution will be discussed.

This study characterized the thermal conductivity (κ) values of a few commonly available fused-filament fabrication (FFF) type 3D printing materials that have the potential to be used to 3D-print interior architectural wall panels. The materials included polylactic acid (PLA), acrylonitrile butadiene styrene (ABS), and polyethylene terephthalate glycol (PETG). Three infill percentages (20, 60, and 98%) and three infill patterns (grid, zigzag, and honeycomb) were investigated in the study. The characterized thermal conductivity values revealed that these 3Dprinted material sample coupon thermal conductivity values ranged from 0.15 to 0.31 W m¯¹ K¯¹ and were comparable to gypsum plaster, drywall, and hardwood. Generally, lower infill densities (e.g., infill percentage ~20%) contributed to sample coupons with lower thermal conductivity values (e.g., κ~0.15 W m¯¹ K¯¹). Zigzag and honeycomb infill patterns generally showed lower thermal conductivity values (~30 to 60% lower κ-value) than grid-type infill patterns for a given infill density. 3D-printed sample coupons with PLA material indicated higher thermal conductivity values (~10-33% higher κ-value) when compared to ABS and PETG 3D-printed sample coupons. The study results also showed that 3D printing could fabricate components such as interior building panels with desired target thermal conductivity values. The findings also showed that by selecting the combination of 1) material, 2) infill pattern, and 3) infill percentage, constant or localized gradient thermal conductivity values could be engineered that are difficult to achieve with traditional interior building materials.

Today, the aluminum heat sink is one of the most expensive and heaviest components in an LED lighting product. Because manufacturers of LED lighting products face the pressure of having to reduce production costs, exploring ways to reduce manufacturing costs by way of using novel materials and manufacturing processes could be a potential solution. 3D-printed polymer-based composite heat sinks with suitable thermal properties and 3Dprinted metal heat sinks could help lighting fixture manufacturers reduce costs. 3D-printed heat sinks have the potential to be customized for increased functionality and visual appeal. This paper presented LED application-specific 3D-printed heat sink thermal performance characterizations. The heat transfer simulations showed that material with effective thermal conductivity values >15 Wm^-1K^-1 can potentially satisfy the thermal management requirements of a 50 W halogen equivalent MR-16 type LED integral replacement lamp. An experiment study was also conducted to evaluate the effect of Cu-plating of the PA-12 heat sinks. The Cu-electroplated heat sinks maintained an operating temperature below 105°C at the LED module case location for a thermal load equivalent to a 35W halogen equivalent MR-16 type LED integral replacement lamp. The 50μm Cu-electroplating thickness had equivalent performance to a 3D-printing material with an effective thermal conductivity of ~3Wm^-1K^-1. The 150μm Cu-electroplating thickness showed similar performance to a material with an effective thermal conductivity of ~6Wm^-1K^-1.

In recent years, there has been an increasing demand for use of advanced luminaires in multitude of applications such as residential & commercial buildings, industrial facilities, and public spaces. These lighting fixtures are designed to provide better illumination, higher energy efficiency, and greater flexibility than traditional lighting systems. Due to the design complexity of these lighting structures, traditional methods of manufacturing are not able to keep up with the demand for customization and innovation. 3D printed electronics can bridge the gap between design and manufacturing, enabling designers and engineers to create advanced lighting fixtures with integrated sensors, wireless communication, and other advanced features. The luminaire that has been manufactured through this effort has been fabricated using 3D printing processes Including electrically conductive inks to print the circuit for illumination and sensing capabilities. Surface Mount Technology (SMT) and supporting electronics has been attached to the printed traces. Light Emitting Diodes (LEDs) have been mounted on multiple angles to study the effect on efficiency of the luminaire.

With technological advances occurring worldwide, wearable electronics have garnered significant attention within diverse fields, from medical to industry. Carbon Nanotube (CNT) ink has had a big impact on these applications of e-textiles. Conductive patterns can be made by printing the CNT ink directly on fabrics. However, a new process and chemical have been tested, where alternatively, a conductive pattern can be applied by laser burning of a lignin-coated layer over a piece of fabric. In this work, we evaluated the quality of patterned laminated polyester ripstop fabric with the two methods of silk screen printing of the CNT ink and the laser burning of lignin. A major focus within these two methods is their resistance values. CNT ink has succeeded with a lower four-probe resistance of about 19.69 Ω/, making it preferable for wearable applications. However, patterning can become an issue when coating CNT ink. Laser burning has its pros and cons: while it can be much simpler to pattern, it has a much higher four-probe resistance of about 49.21 Ω/. In this study, the laser power and rastering are evaluated and compared to the resistance values of CNT ink coating. With this success, further testing on different fabrics and patterns can lead to more inexpensive yet efficient applications and devices.

In the modern world, wearable electronics are potentially intensifying a transformation of the military, aerospace, medical, industrial, and commercial industries. However, manufacturing electronic circuits or devices directly on fabrics is a major challenge. In this study, we have addressed the issue by developing a two-step manufacturing process by coating a piece of polyester fabric with lignin. Initially, a conductive template was achieved on the fabric after laser-burning lignin. In the second step, using an in-house design printer, copper was electroplated over the conductive template to achieve a very low resistive circuit layout. The conductivity measurements were monitored before and after destructive tests such as bending, rolling, washing, and adhesion tests to prove remarkable stability and flexibility. The quality of the conductive patterns was examined through scanning electron microscopy (SEM). Furthermore, the copper deposition method was applied to solder a light-emitting diode (LED) to the applied circuit layout on the fabric. The proposed two-step manufacturing method has a promising potential to fabricate reliable and leading-edge wearable electronics for various applications.

The application of 3D printing in the lighting industry has the promise to transform the production of custom luminaires on demand. The connected lighting system trend in the lighting industry has created the need for custom antenna design and production to improve reliable data transfer. Antenna design accuracy is crucial to the functional efficiency of wireless data communication that could be integrated into lighting products with 3D printing. The trace paths of most paste and ink deposition technologies determine the physical dimensions of the material deposited on the substrate, which can affect the performance of the antenna. A laboratory experiment study was conducted to investigate the relationship between antenna pattern and its dimension and resonance frequency in patch antenna. The study examined the variations in trace paths resulting in antenna dimension variation and compared them with theoretical model predictions of the same antenna design. One of the primary observations in this study was the 3D-printed antennas did not resonate precisely at the modeled 2.4GHz frequency, as predicted by CST Studio Suite®. Further investigation showed that the resonance frequencies were at 2.355 Hz for hatched fill pattern antennas and 2.385 Hz for concentric fill antennas, resulting in 0.045 Hz and 0.015 Hz deviation compared to the designed value of 2.4 GHz.

This paper focuses on the current status of the Additive Manufacture (AM) of lighting, lamps and luminaires. The fundamental technology, that combines free-form, 5 axis 3D printing of structural and electronic components, Surface Mount Device (SMD) placement and pre- and post-processing techniques, is described. The State-of-the-Art of the manufacturing process chain is demonstrated by way of a proof-of-concept of a 3D Printed lamp. The manufacturing the lamp from design concept through the manufacturing process that includes CAD/CAM operations, 3D printing and glass cover manufacturing is presented. The outlook in terms of product certification requirements, potential to scale to series production (lot sizes to 10k) and also repair the lamp are considered.

Additive manufacturing has become a vital resource for commercial lighting product development that still has significant obstacles to overcome before utilizing the technology to its fullest potential. This collaborative presentation will discuss three distinct case studies that highlight the different benefits achieved from using 3D printing as part of the manufacturing process. The presentation will conclude with key lessons learned, while expanding on the challenges currently faced as a manufacturer that hinder the ability to fully adopt additive manufacturing.

The development of industrial luminaires is often confronted with design and manufacturing challenges that traditional design, tooling, and fabrication methods are not best suited. Additive manufacturing (3D printing) offers a means to implement complex shapes and component customizations that conventional methods cannot easily support. Luminaire designs leverage greater weight saving, thermal management optimization, component reduction, and optical distribution customization when utilizing an additive approach. This enhanced flexibility in product design and deployment better supports high mix, low volume applications that are often too specialized to warrant the investment of production tooling to create an appropriate solution. As digital tools like extended/augmented reality mature and allow more precise definitions of an application environment, additive manufacturing design and production methods become increasingly important in the industrial luminaire market vertical. In this article, we seek to highlight some of the benefits of additive manufacturing in developing and deploying a custom solution to illumination of an industrial space.

This PDF file contains the front matter associated with SPIE Proceedings Volume 12670, including the Title Page, Copyright information, Table of Contents, and Conference Committee information.