Process Errors and Aspects for Higher Resolution in Conventional Stereolithography

Due to the rapid development of precision manufacturing technologies, there is a growing market need for appropriate rapid prototyping methods with higher resolution. This paper presents aspects for a general optimization of stereolithography accuracy and gives a deeper analysis of important process errors. Beside a higher precision due to improved optical components, it can be shown that for a better vertical resolution one must mainly reduce the penetration depth of the photopolymer. We found that this is also possible with conventional stereolithography materials by using a different wavelength, achieving cured rugged layers with a thickness of 20 micrometer. The major accuracy aspect lies in the understanding of the layer deposition process. A CFD (computational fluid dynamics) study helps to describe important phenomena of blade based coating techniques. As a result, the inaccuracy of the layer deposition is the general limiting factor in stereolithography. This knowledge can be directly applied to commercial stereolithography systems helping users to achieve higher process accuracy.Mechanical Engineerin

Review and New Aspects in Combining Multipoint Moulding and Additive Manufacturing

Additive manufacturing has become a very important manufacturing method in the last years. With additive manufacturing, a higher level of function integration can be achieved compared to traditional manufacturing technologies. However, the manufacturing of larger parts leads to long construction times. A possible solution is the combination of multipoint moulding with additive manufactured form elements. This article reviews the state of technology for multipoint moulding and additive manufacturing. Moreover, the state of technology is analysed to outline the possibilities and challenges of combining both technologies. The review shows that there has been research on different challenges of the new production process. On the other hand, it turns out clearly that there are many open points at the intersections of both technologies. Finally, the areas where further research is necessary are described in detail

Review and New Aspects in Combining Multipoint Moulding and Additive Manufacturing

Additive manufacturing has become a very important manufacturing method in the last years. With additive manufacturing, a higher level of function integration can be achieved compared to traditional manufacturing technologies. However, the manufacturing of larger parts leads to long construction times. A possible solution is the combination of multipoint moulding with additive manufactured form elements. This article reviews the state of technology for multipoint moulding and additive manufacturing. Moreover, the state of technology is analysed to outline the possibilities and challenges of combining both technologies. The review shows that there has been research on different challenges of the new production process. On the other hand, it turns out clearly that there are many open points at the intersections of both technologies. Finally, the areas where further research is necessary are described in detail

Mouldability of Additively Manufactured Attachments on Multipoint Tools

Enhanced multipoint moulding with additive attachments (EMMA) is a process combining vacuum-assisted multipoint moulding (VAMM) and additively manufactured moulding attachments for carbon fibre reinforced plastics (CFRP) component production. The aim of this initial study is to investigate the mouldability of the additively manufactured attachments on the multipoint tool. For this purpose, two different test specimens were defined, the VAMM machine was adjusted, the attachments were additively built with the robot on the curved silicone interpolation layer and lastly, the CFRP specimens were moulded. The fabrication results were analysed with surface comparisons to check that there was no displacement of the attachments during moulding. A visual evaluation of the manufactured components was carried out, and the overall dimensional accuracy was assessed by comparing the surface with the target geometry. The results showed a very good agreement between the shapes before and after the moulding and thus prove that the attachments were not postponed in the moulding process. The optical evaluation confirms good moulding results for the parts manufactured with the enhanced multipoint moulding with additive attachments. Moreover, the evaluation shows that the major parts of the specimens comply with the permissible tolerance of t = 6 mm defined in ISO 20457. To the authors’ best knowledge, this is the first study that has investigated the entire EMMA process and systematically proved the mouldability of the additively manufactured attachments on multipoint tools

Comparison of Conventional and Robotic Fused Filament Fabrication on Silicone Build Plates

The objective of this study is the investigation of the transferability of the material extrusion process from conventional to robotic fabrication on silicone build plates for use in Enhanced Multipoint Moulding with Additive Attachments. Therefore, the study is based on two series of experiments. The first series of tests used a conventional plant extended by a silicone construction platform. In comparison, a six-axis industrial robot was chosen to produce the test specimens in the second series of tests. The comparisons of adhesion strengths and relative shape deviations are used to validate the transferability. The results of the tests show a very good transferability of the process from conventional to robotic production. Whilst angular specimen geometries can be transferred directly, for round specimen geometries, the results show a need for further adaptation to the robot kinematics. The round specimen geometries showed deviations in the surface quality caused by an over-extrusion in the robotic manufacturing. This over-extrusion results from the slicing process in combination with the robot control and may be avoided through further optimisation of the process parameters. Overall, to the best of our knowledge, this study is the first that successfully demonstrates the transfer of Fused Filament Fabrication (FFF) from a conventional system to manufacturing using robots on silicone build plates for the use in Enhanced Multipoint Moulding with Additive Attachments