Community Research and Development Information Service - CORDIS

H2020

ToMax Report Summary

Project ID: 633192
Funded under: H2020-EU.2.1.5.1.

Periodic Reporting for period 1 - ToMax (Toolless Manufacturing of Complex Structures)

Reporting period: 2015-01-01 to 2016-06-30

Summary of the context and overall objectives of the project

Lithography based additive manufacturing technologies (L-AMT) are capable of fabricating parts with excellent surface quality, good feature resolution and precision. ToMax aims at developing integrated lithography-based additive manufacturing systems for the fabrication of ceramic parts with high shape complexity. The focus of the project is to unite industrial know-how in the field of software development, photopolymers and ceramics, high-performance light-sources, system integration, life cycle analysis, industrial exploitation and rewarding end-user cases.
The consortium will provide 3D-printers with high throughput and outstanding materials and energy efficiency. The project is clearly industrially driven, with 8 out of 10 partner being SMEs or industry. During the first project period, the consortium successfully achieved a number of technical milestones, and also proofed its ability to provide impact beyond technological issues:
(1) A new class of high-performance 3D-printers with excellent feature resolution (20micrometer) and increased build volume has been set up. The system is based on dedicated laser optics which have been specifically designed and manufactured for ToMax by one of the partners.
(2) The system has been modified in a way that allows processing of high-viscosity materials. These improved capabilities enable the use of highly filled photopolymers. ToMax was therefore able to print silicon nitride parts with outstanding mechanical properties. These successful developments led to first follow-up industrial projects with automotive end users.
(3) To further increase the impact of these technological and scientific developments, the ToMax team put significant efforts towards streamlining the exploitation and dissemination of the obtained results. Part of these activities is a profound life cycle assessment of the used materials and processes. Furthermore, a specific roadmap and plan for disseminationand exploitation has been provided. As result of these activities, a recently established spin-off of one of the academic partners has already signed a licensing agreement including intellectual property generated within ToMax.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The performed work in the first project period was covering the following topics:
(1) Definition of end user requirements for multiple applications in biomedical engineering, lighting technology and energy industry. These enduser applications focus on the use of advanced ceramics, mainly aluminum oxide and silicon nitride. During the course of the project, optimized geometries for these applications have been defined and first prototypes have been successfully fabricated.
(2) Setting up a lithography-based Additive Manufacturing System which provides excellent feature resolution while also providing a large build volume. To achieve this, a new optical setup was developed and manufactured by the responsible ToMax partner and has been provided to the consortium. Using this setup, the first generation AM system is now able to print structures with an outstanding feature resolution of 20micrometer.
(3) Key requirement for meeting the enduser requirements are innovative material solutions. The developed AM system allow the processing of materials which are significantly more viscous than in state of the art AM systems. Using ToMax technology, the material spectrum can therefore enhanced significantly, leading to final materials with improved mechanical qualities. Of specific interest in the first project period where silicon nitride materials. The consortium could show that these materials can be processed and the resulting parts exhibit excellent strength (>700MPa) and density values (3.25g/cm³).
(4) Due to the input of all partners, the consortium was able to set up the worldwide first Life Cycle Assessment (LCA) of lithography-based AMT covering the whole process chain from materials production, resin preparation, structuring and post-processing. This will allow an in-depth analysis of the ecological impact of AM technologies in manufacturing.
(5) From the beginning of the project, the consortium was aiming towards a clear roadmap for exploitation of the obtained results. Due to this stringent exploitation strategy a first licensing agreement could be signed and two partners are aiming to further eyploit ToMax technology for enhancing their product portfolio.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

Regarding WP2 on computational modeling and software framework for additive manufacturing, there are interesting progresses beyond the state of the art (some of them already advanced in Deliverable 8.2), which should be highlighted:

(1) Software with novel ways of interacting with the computer-aided designs of the geometries to be printed and with new aspects linked to the preparation of additive manufacturing processes by photopolymerization has been developed. Main progresses beyond the state of the art include: a) Features for dividing the geometry into different zones for defining different polymerization levels (i.e. for differentiating the real part and the support structures), which is aimed at an easier and more automatic removal of supports during cleaning. b) The incorporation of new libraries of support geometries for improving the eco-efficiency of the overall process by using less support material or by combining different support geometries, in some cases bioinspired, for an improved control of the printing process. c) The possibility of defining different geometries of point-like contacts between the support structures and the parts to be printed, which may lead to wash-away support structures and increase overall process efficiency.
(2) A complete computer-aided design library of porous, lattice and functionally graded structures, whose mechanical, thermal and fluidic properties have been assessed by means of FEM-based modeling, has been developed. It constitutes one of the most complete libraries available so far of such “metamaterials”, which can be directly applied to the development of final applications (typically using Boolean operations between the geometries of the library and the geometries of the concrete device) and may serve to optimized the mechanical, thermal and fluidic performance of a wide set of products in fields including energy, transport, architecture, health and product design. Being complex porous geometries, with a material distribution that can be adapted to the desired performance, they are especially suitable to their manufacture by means of additive approaches and help to optimize the use of material and to minimize environmental impacts.
(3) Processes for controlling not just the inner structure of additive manufactured parts, but also the surface properties of computer-aided designs and of related final prototypes have been developed, validated and compared with state-of-the-art software for texturing designs.
(4) The developed designs of porous, lattice and functionally graded structures and of textured surfaces have been printed by using the different available technologies, which has served to obtain data from systematic characterization trials and to compare the current limits (in terms of part size, precision, length of cantilever structures, level of detail attainable and other relevant parameters for the additive manufacturing field) of different photo-polymerization technologies and related materials.

In WP3 improved debinding and sintering protocols for postprocessing of printed alumina parts enabled the the realization of relative densities of 99.7 % without using any sorts of sintering aids. This constitutes a significant improvement compared to the previously feasible 99.4 % for lithographic AM as well as other AM approaches in general (relative densities <99 %). Accompanying mechanical (strength, hardness) and microstrctural (SEM) characterization are in progress.
For silicon nitride-based materials the results of Tomax constitute the first report of AM-produced parts with equivalent material properties to conventionally fabricated counterparts. Further investigations to confirm these first findings are in progress.

Regarding the WP4, the progress beyond the state of art can be found mostly in improvements of the delivered first generation light engine in comparison to other products already on the market. Particular innovative features of this light engine system are:
(1) It can be considered the first light engine on the market which uses a laser diode array illumination system (Phaser P1 by Osram), which can be considered a highly energy-efficient source of light for future 3D printing system. The utilisation of this phaser, which was initially developed for white-light applications, by removing the colour wheel can also be described as a progress.
(2) The light engine has a very high optical output power (> 8W, more than 600 W/m² irradiance in the image plane) due to the laser array illumination system and careful design matching of all components, which is higher than comparable systems on the market, thus reducing the cycle time of the 3D-printing process.
(3) The image quality in terms of contrast, illumination uniformity, image skewness or distortion can be considered paramount in comparison to existing light engines in the market. For example, the image distortion is <0,1%, while most competitors only achieve values <1%.
(4) Adjustment elements for the spatial position of the various components in the optical path have been integrated, thus allowing an optimisation of the position to achieve the mentioned optical quality parameters. Furthermore, there exists an adjustment possibility of some lenses within the system to correct errors of the image plane (astigmatism, coma) to compensate aberrations caused by production tolerances.
(5) It is the first time that provisions have been taken for the combining mirror system (including correcting plate and vat) during the optical calculation of the lens, thus ensuring an optimum in image quality terms.
(6) A two-camera system has been developed by using high-resolution cameras (developed for imaging vision applications) for the alignment of the laser scanner system and the light engine.

Regarding WP5, the development of a Lithography based Additive Manufacturing Technology (L-AMT) system, progresses and experiences on the innovative exposure concept and the upscaling of several components like the size of the building envelope were obtained. These progresses should be listed:
(1) A high throughput L-AMT system, designed from scratch, with high- feature-resolution and large building volume (144x90x100 mm³) has been developed. The upscaling of such a system, with respect to previous construction from the TUW, was achieved. This screening was important for obtaining a TLR6-state within ToMax. New experience with this enlarged building platform size could be gathered. As expected, the separation forces of a fully cured building platform lead to higher separation forces and need to be diminished. A heating system, which enables the processing of resins of higher viscosity, was implemented. These process conditions are needed to generate wash-away support structures, which is a pursued goal within WP5.
(2) The highlight beyond the state of the art is a combination of two exposure units, which separately are intended for L-AMT; a DLP Light Engine (LE) (projecting bitmaps for layer generation) and a laser-scanner system (exposing vector-based structures for layer generation) where constructed and tested separately. A simultaneous acceleration of the exposure step and good surface qualities should be achieved by combining both systems. In collaboration with the project partner In-Vision (Workpackage-leader WP4), this optical setup was designed. It contains a laser system (laser diode module, beam-expander-optics, laser-scanner), a DLP LE (With integrated high-power Phaser light source) and a semi-transparent mirror. The latter is needed combining the two light sources.
(3)In collaboration with the project partner Lithoz (Workpackage-leader of WP3) the software-framework of the L-AMT system was compiled and implemented. Due to a flexible program structure, an adaption for the proposed initial calibration (For matching both light sources) and an online monitoring is provided.

Regarding WP6 on end-user applications, there are important novel applications of additive manufacturing technologies developed within TOMAX (some of them already advanced in Deliverable 8.2), including:

(1) Applications in energy engineering, which benefit from the use of complex geometries and structures for improved heat dissipation, heat transfer, promotion of turbulence and integration of structural and thermal functionalities, have been conceived, designed, implemented and tested for validation purposes. New concepts of heat exchangers, of heat dissipation systems with structural function and of solid-oxide fuel cells are being designed within the project and first prototypes have helped to validate the potential of these new approaches in terms of integration of functionalities by using more complex geometries and regarding the minimization of manufacturing and mounting steps, which simplifies manufacture to just one step, from the design to the final product, hence potentially increasing process efficiency even when compared to well-established traditional manufacturing procedures.
(2) Applications in chemical and biomedical engineering, in which the use of ad hoc defined porous or lattice structures and microtextured surfaces may improve the reactions involved or lead to biomimetic and biomechanical performances. Lattices with functional gradients of density and potential application as filters or as scaffolding elements for a wide set of applications have been designed and manufactured with a remarkable degree of precision. Micro-reactors with microtextured surfaces for improving mixing and with cantilever integrated membranes, for separating different areas within these micro-systems, have been also designed and manufactured with special emphasis on validating the degree of control attainable upon the final surfaces and the possibility of substituting multi-layered devices made of different components, by integral micro-reactors or labs-on-chips manufactured in one step.
To give concrete examples:
* OSRAM: For the development of an optimal heat sink solution for high performance light engines produced by L-AMT, the following beyond the state progresses are notable:
In state of the art approaches of L-AMT, pure ceramic materials were typically used. A material combination of metal and ceramic precursor materials poses a considerable challenge for L-AMT. In this special application, a density factor of 2.5 (Mo, Al2O3) had to be handled within the liquid precursor system, where segregation effects can play a dominant role. As could be shown, using the adapted Lithoz-system is able to prevent the material combination from segregation.
In state of the art approaches of L-AMT, either microscopically small or macroscopically large structures can be realized. Another challenge is to combine both requirements in a single printing process. The functionality of a heat pipe system crucially depends on a fine-structured wick and a macroscopic container. Lithoz was able to print microscopic structures down to 150 microns feature resolution within parts of several centimeters.
The socio-economic impact and the wider societal implications of the project so far: As end user, OSRAM needs a functional prototype to estimate the effectivity of the cooling device for a new generation of high power light engines. So far, only preliminary studies are available, such that in this very moment, the wider societal implications cannot be thoroughly evaluated.
* SYALONS: Could produce extremely complex and increasingly large parts made of Si3N4. The development of such parts is likely to enable the use of Syalon materials in new applications where it was previously limited to relatively simple geometries. Small Syalon springs were produced. The customer of Syalons claims that a successful solution could result in a requirement for millions of the springs. The successful application of Syalon springs within the automotive industry could improve vehicle performance, fuel economy and performance.
* RHP: During Tomax-project the consortium has managed to manufacture dense silicon nitride ceramic with remarkable density > 3,2g/cm³. That is the first time, that it can be reported, a dense, AM-manufactured silicon nitride ceramic has been developed. The high density is a hint on good mechanical strength – nevertheless this has to be analyzed to be proved, which is still in progress. Therefore AM-manufacturing will give the opportunity to cover new markets such as medical instruments or textile machinery components. Especially the market of medical instruments often required small and medium quantities of ceramic items (50 – 500 pcs/y), that are difficult to sell cost covering, because the initial costs for molds (> € 5.000,-/mold) have to be spread over a small qty of items. Tomax covers this niche and opens this market for Rauschert. Silicon Nitride is a material, that has some advances against zirconia, because it can be used several time, it shows no decrease of mechanical strength when treated in hot steam for sterilization. It is the goal to increase the share in this market in the Rauschert group and safe employments within the European Union. Germany has s strong position in this markets (besides Switzerland), but completion from low-cost countries is strong. Results achieved in TOMAX will help to keep employment in the EU and strengthen the economic power of the companies in the consortium.
* UPM: UPM has been performing computational modelling for obtaining material- and cost-efficient eco-designed products and for incorporating additional special features to different applications being developed, which will be detailed along present periodic report and which have been further detailed in journal publications and featured in some conferences. In short, on the basis of the libraries of complex geometries systematicaly developed and assessed, as part of WP2 (see Deliverable on „Prototypes of relevant geometries and data from systematic characterization trials“), the limits of AM-technologies in terms of precision, attainable complexity and material performance, have been better understood and expanded. Such complex geometries are being methodicaly applied to the development of end user applications with improved mechanical, thermal and fluidic response, with optimized environmental impacts for a desired response, and with integration of functionalities for improved performance. Some interesting tool-less manufactured complex geometries have been successfully applied to the development of new device concepts and applications in energy engineering, biomedical and chemical engineering, automation and robotics, materials science,among other fields, and there are interesting progresses beyond the state of the art, which should be highlighted:
- Micro-heat exchangers with complex networks of fluidic channels towards more compact and integrated systems have been designed (with orientation to AMT), computationally modelled for optimized operation and obtained as single part fully integrated devices in just one manufacturing step. Even though these cases of study have been obtained (as a preliminary approach) by additive photo-polymerization in epoxy resin, a similar procedure may be applied to the development of micro heat exchangers using alternative liquid phase additive procedures including lithography-based ceramic manufacture.
- Novel solutions for heat dissipation, combining mechanical, thermal and fluidic performances, have been designed, computationally modelled for optimized operation and obtained as single part fully integrated devices in just one manufacturing step. First concepts have been applied to the refrigeration of high-concentration solar energy chips and have been obtained in epoxy resin, but a similar approach can lead to high performance systems in ceramics and for other dissipation purposes.

- Micro-reactors with cantilever membranes separating different reaction chambers linked to complex networks of channels have been designed, modeled for evaluating the potential manufacture of cantilever membranes within complex devices and manufactured using conventional laser stereolithography and epoxy resin in a preliminary approach and lithography-based ceramic manufacture (Lithoz) as final validation. These micro-reactors are in fact new concepts for the MEMS and lab-on-chip industries, which benefit from integration (as the devices are obtained in a single step and as monolithic parts, hence avoiding joining of different componentes, preventing leakage in micro-fluidic systems and simplifying production).
- Micro-vascular shape-memory actuators with complex geometries have been designed, simulated and manufactured additively for the first time. These devices benefit from the possibility of using micro-channels of hot fluid for activating the „shape-memory effect“ of the epoxy resin, with which they are obtained, towards controlled actuation.
- Functionally graded scaffolding structures have been manufactured, using lithography-based ceramic manufacture (Lithoz) after some designs from the libraries developed in WP2, and constitute nice examples of micro-structures with biomimetic features with potential as tissue engineering scaffolds and in vitro models for studying bone. Among these scaffolding structures, it is also important to cite the first-ever additively manufactured auxetic meta-material, with potential also for the development of active filters and of resonant devices.
- Several proofs-of-concept have been also designed, modelled and manufactured (in a preliminary approach using laser stereolithography and epoxy resins) for exploring the possibilities of AMT in other fields.
Gears with porous and lattice structures for automotion, micro-textured surfaces for improved lubrication in machine elements, micro-textured surfaces for enhanced turbulence and reaction speed in solid-oxide fuel cells and actuators for soft robotics based on complex bioinspired geometries are some examples, which will be improved and expanded along the following months of TOMAX project.

Regarding WP7 on life-cycle assessment, apart from the work performed to obtain the significant parameters and values of the different additive manufacturing technologies involved within TOMAX and of the most relevant industrial competing technologies, in order to develop a systematic methodology of life-cycle assessment in the field, there are also concrete progresses such as:

(1) Several test geometries with complex geometries and some application examples have been specifically designed to serve as probes for a standardized and systematic assessment of eco-impacts in additive manufacturing, when compared with more conventional technologies.
(2) A complete study regarding the impact of different support geometries on the environmental impacts (measured in equivalent kg of CO2 and in terms of materials’ saving) and cost (measured in Euro) has been performed using laser stereolithography as additive manufacturing “gold-standard” and quantitative data have been systematically gathered. The study shows that the use of improved supports developed during TOMAX, depending on part geometry, lead to support material savings with values typically ranging from a 40% to almost an 80%, accounting for an overall material saving from around 10% to around 50%. Related cost reductions typically reach values from around 10% to around 40%. (Such results are summarized in form of article accepted for publication in the Journal of Industrial Ecology for a special issue on environmental aspects of additive manufacturing, as listed in the publication list).

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