@unpublished{13346, abstract = {{This article discusses the additive manufacturing and post-processing of axicons, and their performance evaluation using attenuation and near-field-measurements based fundamental techniques. The axicons are manufactured using the materials cyclic olefin copolymer (TOPAS) and polymethyl methacrylate (PMMA), for their respective use in terahertz and near-infrared applications. An emphasis is placed on the dip-coating-based post-processing. Interval dipping and intermittent hardening lead to excellent surface finish and transparency in case of additively-manufactured near-infrared axicons. The dip-coated samples exhibit surface roughness of sub 10nm, and a uniformly distributed thin layer coating over the axicon surface. In addition to the improved surface finish and transparency, the coatings are also closely matched in refractive index to the axicon material. Such post-processed axicons pave the way for rapid-prototyping and production.}}, author = {{Shrotri, Abhijeet Narendra and Starsaja, Annamarija and Joshi, Suraj and Preu, Sascha and Stübbe, Oliver}}, booktitle = {{Optica Open}}, issn = {{2334-2536 }}, keywords = {{additive manufacturing, stereolithography, dip-coating, post-processing}}, pages = {{5}}, publisher = {{Optica Publishing Group}}, title = {{{Multispectral characterization of additively manufactured and dip-coated axicons}}}, doi = {{https://doi.org/10.1364/opticaopen.31149016}}, year = {{2026}}, } @unpublished{13363, abstract = {{This article discusses the additive manufacturing and post-processing of axicons, and their performance evaluation using attenuation and near-field-measurements based fundamental techniques. The axicons are manufactured using the materials cyclic olefin copolymer (TOPAS) and polymethyl methacrylate (PMMA), for their respective use in terahertz and near-infrared applications. An emphasis is placed on the dip-coating-based post-processing. Interval dipping and intermittent hardening lead to excellent surface finish and transparency in case of additively-manufactured near-infrared axicons. The dip-coated samples exhibit surface roughness of sub 10 nm, and a uniformly distributed thin layer coating over the axicon surface. In addition to the improved surface finish and transparency, the coatings are also closely matched in refractive index to the axicon material. Such post-processed axicons pave the way for rapid-prototyping and production.}}, author = {{Shrotri, Abhijeet Narendra and Starsaja, Annamarija and Joshi, Suraj and Preu, Sascha and Stübbe, Oliver}}, booktitle = {{Photonics: Open Access Journal}}, issn = {{2304-6732 }}, keywords = {{additive manufacturing, stereolithography, dip-coating, post-processing}}, pages = {{15}}, publisher = {{MDPI }}, title = {{{Multispectral Characterization of Additively Manufactured and Dip-Coated Axicons}}}, doi = {{https://doi.org/10.20944/preprints202602.0389.v1}}, year = {{2026}}, } @misc{13495, abstract = {{The use of additive manufacturing for rapid prototyping of near-infrared and terahertz components provides seamless and error-free production. This article discusses the additive manufacturing and post-processing of axicons and their performance evaluation using attenuation and near-field-measurements based fundamental techniques. The axicons are manufactured using the materials cyclic olefin copolymer (TOPAS) and polymethyl methacrylate (PMMA), for their respective use in terahertz and near-infrared applications. The optical and terahertz components manufactured using traditional 3D-printing processes, e.g., fused filament fabrication or stereolithography apparatus exhibit high surface roughness in the range of 15 ± 2.5 µm, resulting in undesired propagation and scattering in the near infrared wavelengths. This research work proposes an economical post-processing technique for additively manufactured terahertz and near-infrared axicons for applications in multispectral characterization, e.g., bio-sensing. The authors used an enhanced method of dip-coating, which involves interval dipping and intermittent hardening to achieve better surface finish. An emphasis is placed on interval dipping and intermittent hardening, which lead to excellent transparency in case of additively-manufactured near-infrared axicons. The dip-coated samples exhibit surface roughness below 10 nm. With the use of heated resin material as the coating layer, due to reduced viscosity, the resin material distributes uniformly over the surface of the 3D-printed terahertz and near-infrared axicons. The authors also observed that the DOF length deviation between unprocessed and enhanced dip-coated axicons remains within the measurement error estimation from analytical calculations. In addition to the improved surface finish and transparency, the coatings are also closely matched in refractive index to the axicon material. Such post-processed axicons pave the way for producing a wide array of systems in the fields of communication, imaging, and bio-sensing.}}, author = {{Shrotri, Abhijeet Narendra and Starsaja, Annamarija and Joshi, Suraj and Preu, Sascha and Stübbe, Oliver}}, booktitle = {{Photonics}}, issn = {{2304-6732}}, keywords = {{additive manufacturing, stereolithography, dip-coating, post-processing}}, number = {{3}}, publisher = {{MDPI AG}}, title = {{{Multispectral Characterization of Additively Manufactured and Dip-Coated Axicons}}}, doi = {{10.3390/photonics13030264}}, volume = {{13}}, year = {{2026}}, } @unpublished{13029, abstract = {{Additive manufacturing of optical, electrical and mechanical components is a beneficial approach for rapid prototyping of components and error elimination with short turn around times. However, additively manufactured components usually have rough surfaces which need post-processing, in particular for optical components where the surface roughness must be a small fraction of the wavelength. We demonstrate an innovative and economical approach by dip-coating with the same resin as used for printing, providing high transparency of the 3D-printed optical components and reduced surface roughness with perfect index matching of the coating layer in a simple post processing step. The surface roughness of the 3D-printed optical components drops to 5 nm (arithmetic average) after the dip-coating process. We observed significant performance enhancement after comparing the unprocessed optical components and dip-coated optical components, including achieving optical transparency and shiny surface finish of previously rough surfaces.}}, author = {{Shrotri, Abhijeet Narendra and Preu, Sascha and Stübbe, Oliver}}, booktitle = {{Coatings : open access journal}}, keywords = {{additive manufacturing, post-processing, optics, dip-coating}}, pages = {{10}}, publisher = {{MDPI}}, title = {{{Achieving Transparency and Minimizing Loss of Rough Additively Manufactured Optical Components by a Dip-Coating Surface Finish}}}, doi = {{10.20944/preprints202501.1899.v1}}, year = {{2025}}, } @misc{12424, abstract = {{Additive manufacturing of optical, electrical, and mechanical components is a beneficial approach for the rapid prototyping of components and error elimination, with short turnaround times. However, additively manufactured components usually have rough surfaces that need post-processing, particularly for optical components, where the surface roughness must be a small fraction of the wavelength. We demonstrate an innovative and economical approach by dip-coating with the same resin used for printing in a simple post-processing step, providing high transparency to the 3D-printed optical components and reducing surface roughness while achieving perfect index matching of the coating layer. The surface roughness of the 3D-printed optical components drops to 5 nm (arithmetic average) after the dip-coating process. We observed significant performance enhancements after comparing the unprocessed optical components and the dip-coated optical components, including optical transparency and a shiny surface finish for previously rough surfaces.}}, author = {{Shrotri, Abhijeet Narendra and Preu, Sascha and Stübbe, Oliver}}, booktitle = {{Coatings : open access journal}}, issn = {{2079-6412}}, keywords = {{additive manufacturing, post-processing, optics, dip-coating}}, number = {{2}}, publisher = {{MDPI AG}}, title = {{{Achieving Transparency and Minimizing Losses of Rough Additively Manufactured Optical Components by a Dip-Coating Surface Finish}}}, doi = {{10.3390/coatings15020210}}, volume = {{15}}, year = {{2025}}, } @misc{12801, abstract = {{The present contribution derives a theoretical framework for constructing novel geometrical constraints in the context of density-based topology optimization. Principally, the predefined geometrical dimensionality is enforced locally on the components of the optimized structures. These constraints are defined using the principal values (singular values) from a singular value decomposition of points clouds represented by elemental centroids and the corresponding relative density design variables. The proposed approach is numerically implemented for demonstrating the designing of lattice or membrane-like structures. Several numerical examples confirm the validity of the derived theoretical framework for geometric dimensionality control.}}, author = {{Gerzen, Nikolai and Mertins, Thorsten and Pedersen, Claus B. W.}}, booktitle = {{Structural and Multidisciplinary Optimization}}, issn = {{1615-147X}}, keywords = {{Manufacturing constraints, Topology optimization, Geometric constraints, Gradient based structural optimization, Lattice designing, Additive manufacturing}}, number = {{5}}, publisher = {{Springer Science and Business Media LLC}}, title = {{{Geometric dimensionality control of structural components in topology optimization}}}, doi = {{10.1007/s00158-022-03252-7}}, volume = {{65}}, year = {{2022}}, } @misc{7670, abstract = {{Additive manufacturing (AM) and rapid prototyping process (RPP) have revolutionized the production of 3D objects in the last few decades. RPP has considerably increased the rate of production and the possibility of manufacturing prototypes in the fields of electrical, optical, and mechanical engineering. The manufacturing of optical prototypes including spherical, aspheric, and special kinds of lenses and lens arrays has reformed the fabrication of optical components. In this paper, specifically designed lens array prototypes for application in visible light communication (VLC) are introduced. These lens array prototypes are manufactured using the stereolithography apparatus (SLA) process. These lens arrays are designed to achieve optimal transmission of the light beam for VLC systems. One of the prototypes from the lens arrays contains primarily four spherical lenses and one thicker convex lens and the other contains one fresnel lens as a substitute for thicker convex lens. These lens arrays are further post-processed to achieve the required transparency. These lens array prototypes are tested using laser and LEDs. The ON-OFF keying modulated light beam was transmitted through the lens array at the sender side and focused on the photo-receiver using another lens array at the receiver side which is 200 cm apart. After evaluating these lens prototypes, it can be concluded that with appropriate post-processing and high-resolution stereolithography based manufacturing, a low data rate VLC link can be formed.}}, author = {{Shrotri, Abhijeet Narendra and Beyer, Micha and Schneider, Daniel Johann and Stübbe, Oliver}}, booktitle = {{Laser 3D Manufacturing VIII}}, editor = {{Helvajian, Henry and Gu, Bo and Chen, Hongqiang}}, isbn = {{978-1-5106-4189-1}}, issn = {{1996-756X}}, keywords = {{Additive manufacturing, 3D printing, Stereolithography apparatus, Spherical lenses, Fresnel lenses, Visible light communication}}, location = {{San Francisco }}, publisher = {{Society of Photo-Optical Instrumentation Engineers}}, title = {{{Manufacturing of lens array prototypes containing spherical and fresnel lenses for visible light communications using stereolithography apparatus}}}, doi = {{10.1117/12.2586907}}, volume = {{11677}}, year = {{2021}}, } @misc{12789, abstract = {{Additive manufacturing is being increasingly focused on the production of end-use parts. Compared to the prototyping application, the production of end-use parts demands a higher level of repeatability and process quality. To achieve this, increased knowledge is required about the influence of various process parameters on the part characteristics and the parameter interrelations. Design of Experiment methods can be applied to gain knowledge on the process behavior, but the applicability of different DoE methods for AM processes has to be validated. This paper describes the application of a definitive screening design for the identification of influencing parameters in Laser Powder Bed Fusion of CoCrW alloy. The impact of various hatch parameters on the part porosity is analyzed. The experimental setup and results are described. The results are validated in an additional test series, comparing the part quality achieved by parameter-sets obtained by different optimization approaches. Furthermore, the correlation of the porosity towards mechanical properties is investigated. Finally, the opportunities and limitations of the method are discussed.}}, author = {{Huxol, Andrea and Villmer, Franz-Josef}}, booktitle = {{International Journal of Computer Integrated Manufacturing}}, issn = {{1362-3052}}, keywords = {{Additive manufacturing, quality control, process qualification, process control, screening design}}, number = {{4-5}}, pages = {{556--567}}, publisher = {{Taylor & Francis}}, title = {{{Experimental approach towards parameter evaluation in laser powder bed fusion of metals}}}, doi = {{10.1080/0951192x.2021.1901313}}, volume = {{35}}, year = {{2021}}, } @misc{12790, abstract = {{n the last years, Additive Manufacturing, thanks to its capability of continuous improvements in performance and cost-efficiency, was able to partly replace and redefine well-established manufacturing processes. This research is based on the idea to achieve great cost and operational benefits especially in the field of tool making for injection molding by combining traditional and additive manufacturing in one process chain. Special attention is given to the surface quality in terms of surface roughness and its optimization directly in the Selective Laser Melting process. This article presents the possibility for a remelting process of the SLM parts as a way to optimize the surfaces of the produced parts. The influence of laser remelting on the surface roughness of the parts is analyzed while varying machine parameters like laser power and scan settings. Laser remelting with optimized parameter settings considerably improves the surface quality of SLM parts and is a great starting point for further post-processing techniques, which require a low initial value of surface roughness.}}, author = {{Simoni, Filippo and Huxol, Andrea and Villmer, Franz-Josef}}, booktitle = {{Journal of Intelligent Manufacturing}}, issn = {{1572-8145}}, keywords = {{Direct rapid tooling, Toolmaking, Additive manufacturing process chain, Process control, Production systems, Selective laser melting, Surface roughness, Laser surface remelting}}, number = {{7}}, pages = {{1927--1938}}, publisher = {{Springer Science and Business Media}}, title = {{{Improving surface quality in selective laser melting based tool making}}}, doi = {{10.1007/s10845-021-01744-9}}, volume = {{32}}, year = {{2021}}, } @misc{12791, abstract = {{Additive manufacturing is being increasingly focused on the production of end-use parts. Compared to the prototyping application, the production of end-use parts demands a higher level of repeatability and process quality. To achieve this, increased knowledge is required about the influence of various process parameters on the part characteristics and the parameter interrelations. Design of Experiment methods can be applied to gain knowledge on the process behavior, but the applicability of different DoE methods for AM processes has to be validated. This paper describes the application of a definitive screening design for the identification of influencing parameters in Selective Laser Melting. The experimental setup and results are described and opportunities and limitations of the method are discussed. (C) 2019, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.}}, author = {{Huxol, Andrea and Villmer, Franz-Josef}}, booktitle = {{13th International-Federation-of-Automatic-Control (IFAC) Workshop on Intelligent Manufacturing Systems (IMS)}}, issn = {{2405-8963}}, keywords = {{Additive manufacturing, quality control, process qualification, process control, screening design}}, location = {{Oshawa, CANADA}}, pages = {{270--275}}, publisher = {{Elsevier BV}}, title = {{{DoE Methods for Parameter Evaluation in Selective Laser Melting}}}, doi = {{10.1016/j.ifacol.2019.10.041}}, volume = {{52}}, year = {{2019}}, } @misc{12792, abstract = {{Additive Manufacturing has arisen as a ground-breaking set of technologies that, thanks to their capability of continuous improvements in performance and cost-efficiency, was able in the last years to replace well-established manufacturing processes. Proficiency in the fabrication of highly complex parts forced this astonishing development. This research is based on the idea that through the integration of additive and conventional manufacturing technologies it is possible to achieve great cost and operational benefits especially in the field of tool making for injection molding. Such an integrated manufacturing solution could overcome the limitations of independent additive, subtractive, and post-processing procedures by strengthening their potentialities. The present study highlights the opportunities of a synergy between the above-mentioned manufacturing technologies for the optimized fabrication of injection molds. An additive manufacturing process chain is presented, and special attention is given to the surface quality and its optimization directly in the Selective Laser Melting process. The potentialities of the Laser Surface Re-melting technique are analyzed, and the process optimization leads to a reduction of 45% of the average roughness directly in the SLM process. (C) 2019, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.}}, author = {{Simoni, Filippo and Huxol, Andrea and Villmer, Franz-Josef}}, booktitle = {{13th International-Federation-of-Automatic-Control (IFAC) Workshop on Intelligent Manufacturing Systems (IMS)}}, issn = {{2405-8963}}, keywords = {{Direct rapid tooling, toolmaking, additive manufacturing process chain, process control, production systems, selective laser melting, surface roughness, laser surface re-melting}}, location = {{Oshawa, CANADA}}, pages = {{254--259}}, publisher = {{Elsevier BV}}, title = {{{Approach Towards Surface Improvement in Additively Manufactured Tools}}}, doi = {{10.1016/j.ifacol.2019.10.032}}, volume = {{52}}, year = {{2019}}, } @inproceedings{550, abstract = {{Additive Manufacturing (AM) technologies are increasingly used for final part production. Especially technologies for processing of metal, like Selective LaserMelting (SLM), arefocusedin this area. The shift from prototyping towards final part production results in enhanced requirements for repeatability and predictability of the part quality. Machine manufacturers offer process monitoring solutions for different aspects of the production process, like the powder bed surface, the melt pool, and the laser energy. Nevertheless, the significance of these systems is not fully proven and threshold values for the monitored process parameters have to be determined for each product individually. This impedes the development of suitable process control systems. The paper gives an overview ofexistingresearch approaches and available process monitoring systems for SLM and their applicability for predicting certain part characteristics. The existing solutions are evaluated based on own research results. Next, AM specific difficulties for the development of process control tools and possible solutions are discussed.}}, author = {{Huxol, Andrea and Villmer, Franz-Josef}}, booktitle = {{Production Engineering and Management}}, editor = {{Villmer, Franz-Josef and Padoano, Elio}}, isbn = {{978-3-946856-03-0}}, keywords = {{Additive manufacturing, Process capability, Process monitoring, Quality assurance, Final part production}}, location = {{Lemgo}}, number = {{1}}, pages = {{17--28}}, title = {{{Process Control for Selective Laser Melting - Opprtunities and Limitations}}}, year = {{2018}}, } @inproceedings{552, abstract = {{Since additive manufacturing (AM) is continuously growing, the influence of processing conditions and setup parameters on microstructural and mechanical properties of additively manufacturedcomponents needs to be clarified. The paper discusses an experimental approach for the identification of influencing parameters in Selective Laser Melting; this consists of an evaluation of the mechanical and physical properties of final parts, depending on the chosen process parameters. The Design of Experiments is used to get valid results from a limited number of experiments. The research work focuses on the application of a Definitive Screening Design to identify the most important influencing parameters: Several parameters of the hatch and the contour exposure are varied, as well as the position and orientation of the samples in the build chamber. A maraging steel and a CoCr alloy are used, and the mechanical and physical properties of the samples are evaluated. The interdependencies between the variation of the factors and the observed properties are analyzed.}}, author = {{Simoni, F. and Huxol, Andrea and Villmer, Franz-Josef}}, booktitle = {{Production Engineering and Management}}, editor = {{Villmer, Franz-Josef and Padoano, Elio}}, isbn = {{978-3-946856-03-0}}, keywords = {{Additive manufacturing, Process parameters, Design of Experiments, Density measurement}}, location = {{Lemgo}}, number = {{1}}, pages = {{43--55}}, title = {{{Analysis of Influencing Parameters on Mechanical and Physical Properties of SLM Parts}}}, year = {{2018}}, } @inproceedings{553, abstract = {{Selective laser melting is a powder bed fusion technology that uses a laser as an energy source in order to directly build fullydensemetal parts. Optimal fabrication requires a comprehensiveunderstanding of the main processing,as it affectsthe part quality. Wherefore, the objective of this paper is to perform a survey, data checking and collecting ofprovided parameters to compare and contextualize it versus the respective values used in the processby the research studies. The work is focused on cobalt-chromium alloys (CoCr) which are widely used in dental and medical applications. This work focusesonsurfacequality and hardness as built and after the post-processes. As well, the approaches in bond strength after post-processing are considered, comparing the results made by different manufacturing techniques. Finally, this work compares results acquired in surface roughness asbuilt, and tensile strength of parts made by selective laser melting versus the traditional technique cast, before and after heat treatment.}}, author = {{Silva Gimenes Gandara, Joyce and Huxol, Andrea and Villmer, Franz-Josef}}, booktitle = {{Production Engineering and Management}}, editor = {{Villmer, Franz-Josef and Padoano, Elio}}, isbn = {{978-3-946856-03-0}}, keywords = {{Additive manufacturing, Material properties, Part properties, Process parameters}}, number = {{1}}, pages = {{57--69}}, title = {{{Selective Laser Melting - CoCr Approach: Analysis of Manufacturer Parameters Versus Research Results}}}, year = {{2018}}, } @inproceedings{554, abstract = {{Light guiding structures, like optical waveguides or fibers, take an important role in several industries, e.g. communication, sensing, illumination or medical applications. For the latter, it could be very interesting to have the possibility to manufacture problem-adapted structureswith a mechanicalfunctionality andwith additional embedded optical or electrical sensor functionalities.Modern additive manufacturing (AM) technologies like Stereolithography (SLA) or Fused Layer Modeling (FLM) may provide these opportunities.This paper is aimedto figure out the light guiding opportunities of both technologies. For this different kind of structures are built by FLM and SLA. To compare both manufacturing technologies, the layout of each structure is identical for both technologies. After manufacturing, the transmission and the attenuation of the guided light of these structures areanalyzed by measurement.Then the measurement results of the different technologies are compared with each other.}}, author = {{Beyer, Micha and Stübbe, Oliver and Villmer, Franz-Josef}}, booktitle = {{Production engineering and management : proceedings 8th international conference, October 04 and 05, 2018, Lemgo, Germany}}, editor = {{Villmer, Franz-Josef and Padoano, Elio}}, isbn = {{978-3-946856-03-0}}, keywords = {{Additive manufacturing, Embedded optical waveguides, Optical sensors, SLA technology, FLM technology}}, location = {{Lemgo}}, number = {{1}}, pages = {{70--82}}, title = {{{Comparsion of FLM and SLA Processing Technologies Towards Manufacturing of Optical Waveguides for Communicationi and Sensing Applications}}}, year = {{2018}}, } @inproceedings{570, abstract = {{Additive manufacturing (AM) has matured rapidly during the last years due to the advancement of AM machines and materials. Nevertheless, the widespread adoption of AM is still challenged by producing parts with reliable quality. The aim of this paper is t o introduce a first approach to apply in-situ monitoring for quality evaluation of produced parts. Based on the monitored data, a model is developed, in order to predict the quality of ready built parts.}}, author = {{Scheideler, Eva and Huxol, Andrea and Villmer, Franz-Josef}}, booktitle = {{Production Engineeringand Management}}, editor = {{Padoano, Elio and Villmer, Franz-Josef}}, isbn = {{978-3-946856-01-6}}, keywords = {{Nondestructive quality control, Predictive analytics, Metal model, Additive manufacturing}}, location = {{Pordenone, Italy}}, number = {{1}}, pages = {{89--100}}, title = {{{Nondestructive Quality Check of Additive Manufactured Parts Using Empirical Models}}}, year = {{2017}}, } @inproceedings{573, abstract = {{Additive manufacturing (AM) technologies have not only revolutionized product development and design by enabling rapid prototyping. They also gained influence on production in general, mainly because of their direct manufacturing capabilities. In the context of Industry 4.0 and the related process automation, innovative and advanced production technologies with completely new approaches are required [1]. AM technologies contribute to this with their advantages like freedom of design, cost efficient product individualization, and functional integration. On the other hand, AM still shows shortcomings in exploiting its full potential. Most current AM technologies are only applicable for manufacturing with singular materials. In particular, opportunities for processing of optically or electrically conductive materials are still missing. This paper contributes to the advancement of additive manufacturing of two different material variants or even two completely different materials. A special focus is laid on producing a part that combines mechanical with optical or electrical functionalities in one process step. The ultimate goal is to integrate sensor functionalities into an AM object, e.g. strain gauges. Extrusion processes, predominantly Fused Layer Modeling (FLM), are preferred in this research due to their mechanically simple machine setup in which additional functional materials can be adapted easily to the build process. In a first step, the general manufacturability has been evaluated. Thereafter, the resulting optical transmission properties have been analyzed. Especially the attenuation has to remain below a threshold value to accomplish a minimum signal-to-noise ratio.}}, author = {{Ehlert, Patrick and Stübbe, Oliver and Villmer, Franz-Josef}}, booktitle = {{Production Engineering and Management}}, editor = {{Padoano, Elio and Villmer, Franz-Josef}}, isbn = {{978-3-946856-01-6}}, keywords = {{Additive manufacturing, Embedded optical waveguides, Electrical conductors, Embedded systems, FLM technology, Sensors}}, location = {{Pordenone, Italy}}, number = {{1}}, pages = {{127--136}}, title = {{{Investigation on the Direct Manufacturing of Waveguides and Sensors Using FLM Technology}}}, year = {{2017}}, } @inproceedings{575, abstract = {{Additive manufacturing technologies can provide cost and time advantages in mold making, compared to traditional approaches. Nevertheless, their applicability is not yet completely proven, especially in terms of surface finishing. The aim of this research work is to create perfect mold inserts by Selective Laser Melting (SLM) and to optimize surface quality. Therefore a process is developed to reduce the effort of surface quality optimization including a high flexibility in design. The tested process shows that simple and affordable methods can lead to usable molds with only minor restrictions in terms of appearance. Due to the initial reduction of layer thicknesses and distinct settings of laser melting parameters, the surface smoothness is significantly enhanced during the SLM building process. Subsequently blasting, manual grinding, as well as polishing operations, enable a selective smoothening of the surface up to a polished finish. As a result, the built tool parts can be used instantly for injection molding.}}, author = {{Elstermeyer, O. and Villmer, Franz-Josef}}, booktitle = {{Production Engineering and Management}}, editor = {{Padoano, Elio and Villmer, Franz-Josef}}, isbn = {{978-3-946856-01-6}}, keywords = {{Tool making, Direct rapid tooling, Additively manufactured molds, Selective laser melting, Additive manufacturing process chain, Post-processing}}, location = {{Pordenone, Italy}}, number = {{1}}, pages = {{101--113}}, title = {{{SLM Based Tooling for Injection Molding - Focus on Reduced Effort in Surface Quality Optimization}}}, year = {{2017}}, } @inproceedings{579, abstract = {{Selective Laser Melting (SLM) is a powder bed fusion process to produce additively metal parts. From the current point of view, it seems to be one of the most promising additive manufacturing technologies for the production of end use parts. An increasing number of examples prove the successful application of SLM for technical part production. Nevertheless, they also show the enormous effort that is still required to qualify the production process of every single part individually.The present paper gives an overview of the major influencing factors of the SLM process. To get a comprehensive research approach, existing publications on the topic are taken into account as well as own experimental work, evaluating the effects of the process parameters on the relative density of samples made from tool steel. The experimental setup and the results are described and opportunities for the further research work are discussed.}}, author = {{Huxol, Andrea and Scheideler, Eva and Villmer, Franz-Josef}}, booktitle = {{Production Engineering and Management}}, editor = {{Padoano, Elio and Villmer, Franz-Josef}}, isbn = {{978-3-946856-01-6}}, keywords = {{Selective laser melting, Additive manufacturing, Process parameters, Process optimization}}, location = {{Pordenone, Italy}}, number = {{1}}, pages = {{13--34}}, title = {{{Influencing Factors on Part Quality in Selective Laser Melting}}}, year = {{2017}}, } @inproceedings{580, abstract = {{Additive Manufacturing (AM) is increasingly used to design new products. This is possible due to the further development of the AM-processes and materials. The lack of quality assurance of AM built parts is a key technological barrier that prevents manufacturers from adopting. The quality of an additive manufactured part is influenced by more than 50 parameters, which make process control difficult. Current research deals with using real time monitoring of the melt pool as feedback control for laser power. This paper illustrates challenges and opportunities of applying statistical predictive modeling and unsupervised learning to control additive manufacturing. In particular, an approach how to build a feedforward controller will be discussed.}}, author = {{Scheideler, Eva and Ahlemeyer-Stubbe, Andrea}}, booktitle = {{ Production engineering and management : proceedings 7th international conference, September 28 and 29, 2017, Pordenone, Italy }}, editor = {{Padoano, Elio and Villmer, Franz-Josef}}, isbn = {{978-3-946856-01-6}}, keywords = {{Additive manufacturing, Process control, Predictive modeling, Predictive control}}, location = {{Pordenone, Italy}}, number = {{1}}, pages = {{3--12}}, title = {{{Quality Control of Additive Manufacturing Using Statistical Prediction Models}}}, volume = {{2017}}, year = {{2017}}, } @inproceedings{457, abstract = {{Additive Manufacturing (AM) increasingly enables the realization of structures, which have a much greater freedom of design und can therefore better use nature as a design ideal. Bionic design principles have already been introduced into general design approaches, and several topology optimization systems (TO) are available today to increase structural stiffness and to enable lightweight design. AM and TO, used in synergy, promise completely new application areas. However, staircase effects resulting from a layer-by-layer build process and unavoidable support structures which must be mechanically removed afterwards are disadvantageous with respect to surface texture and strength properties. The present article addresses the question of how far the notches resulting from the staircase effect of Additive Manufacturing and the support structures removed decrease the strength of components. Most engineers try to follow the inner flow of forces in a part’s design by smoothening surfaces in notched areas. Considering this, a elected component is investigated with finite element analysis (FEA) with special regard for the concentration of tress arising from surface notch effects. An outlook is given as regards how a reduction of the notch effect from the taircase effect can be achieved effectively.}}, author = {{Scheideler, Eva and Villmer, Franz-Josef and Adam, G. and Timmer, Mirco}}, booktitle = {{Production Engineering and Management Proceedings 6th International Conference}}, editor = {{Villmer, Franz-Josef and Padoano, Elio}}, isbn = {{978-3-946856-00-9}}, keywords = {{Additive Manufacturing, Topology optimization, Staircase effect, Support structures, Stress concentration, Lightweight construction, Design rules, Notch effect}}, location = {{Lemgo}}, number = {{1}}, pages = {{39--50}}, title = {{{Topology Optimization and Additive Manufacturing – A Perfect Symbiosis?}}}, year = {{2016}}, } @inproceedings{473, abstract = {{Additive Manufacturing (AM) describes a number of technologies that generate three-dimensional objects directly from CAD data by joining volume elements. Dental technology is one sector in which the benefits of AM come into effect, as parts such as frameworks or implants are unique objects often with freeform shapes. These objects are difficult and expensive to produce with subtractive or formative technology. During the last decades, the application of digital technologies in the dental industry has increased. Therefore AM has also evolved to become a standard dental framework manufacturing process. While previously the dental laboratory did the complete manufacturing of dental frameworks, AM parts are usually produced by service providers, thus increasing the number of process participants. Under these circumstances, a reliable high quality production must be ensured. This requires a comprehensive Quality Management (QM) concept for the whole process chain. A first step in the evelopment of this QM concept is the definition of the product requirements, from which process specifications can be determined. These specifications build the basis for evaluating the process capability of the Additive Manufacturing process.}}, author = {{Huxol, Andrea and Villmer, Franz-Josef}}, booktitle = {{Production Engineering and Management}}, editor = {{Villmer, Franz-Josef and Padoano, Elio}}, keywords = {{Additive Manufacturing, Dental frameworks, Quality management, Digital manufacturing}}, location = {{Lemgo}}, number = {{1}}, pages = {{15--26}}, title = {{{Special Requirements for Additive Manufacturing of Dental Frameworks}}}, year = {{2016}}, } @inproceedings{598, abstract = {{The aerospace sector is characterized by long product life cycles and a need for lightweight design. Additive manufacturing is a technology that produces parts layer by layer and thus enables the manufacturing of any complex parts at nearly no extra costs. A topology optimization enhances the part’s performance for their special purpose. The results are often complex bionic structures that cannot be produced with conventional manufacturing technologies. The paper analyzes how the high potential of this technologycan be applied to aerospace parts. A topology optimization will be conducted for an aircraft part explaining the crucial points and a life cycle analysis examines the achieved sustainable improvements for the aircraft’s life cycle. }}, author = {{Huxol, Andrea and Villmer, Franz-Josef}}, booktitle = {{Production Engineering and Management}}, editor = {{Padoano, Elio and Villmer, Franz-Josef}}, isbn = {{978-3-941645-11-0}}, keywords = {{Additive manufacturing, topology optimization, aerospace, life cycle costs}}, location = {{Trieste, Italy}}, number = {{1}}, pages = {{207--218}}, title = {{{Hybrid Manufacturing Machines: Combining Additive and Subtractive Manufacturing Technologies}}}, year = {{2015}}, } @inproceedings{671, abstract = {{Additive manufacturing processes such as laser sintering are characterized by a high rate of innovation, are a standard procedure in rapid prototyping and are becoming increasingly important in small-series production. Despite the growing importance of additive manufacturing processes, there are no comprehensive ergonomic studies about work using additive manufacturing systems. This study therefore investigates the working processes of laser sintering systems. The method is guided by the DIN EN ISO 9241-210:2011 standard and helps to record the context of use, to accomplish usability tests and to develop design recommendations. The outcome of the study shows that the efficiency of the laser sintering operating process can be significantly increased by implementing ergonomic recommendations and consequently further improve the employees’ working conditions.}}, author = {{Riediger, Daniel and Hinrichsen, Sven and Villmer, Franz-Josef}}, booktitle = {{Production Engineering and Management}}, editor = {{Villmer, Franz-Josef and Padoano, Elio}}, keywords = {{ergonomic design, additive manufacturing, laser sintering, usability}}, location = {{Lemgo}}, number = {{10}}, pages = {{61--68}}, publisher = {{Hochschule Ostwestfalen-Lippe}}, title = {{{Ergonomic Design of Laser Sintering Systems - Results of an Empirical Study}}}, year = {{2014}}, }