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Item type:Publication, Access status: with files , Praxisbericht: Fachwissenschaft und Berufspraxis verbunden durch kollaboratives Peer Teaching im Studium des Lehramts an Beruflichen Schulen(2020-12-14); ; The systematic nature of the vocational fields in the training programme for teachers at vocational schools is in continuing contradiction to the action orientation at schools. Because of the requirements for individual specializations, it is not always easy to resolve this issue. This study presents a didactic concept that uses a peer-teaching approach to supplement the subject systematics of the subject-specific teaching content with teaching methods that are related to the later teaching profession. The concept was applied and evaluated in two teaching events of the professional field of metal technology in Hamburg. It has led to an increased motivation and in- dependence of the students while maintaining the same academic performance.Publicationtype: Journal Article135 190 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Hybrid Manufacturing for Design - Halbzeugoptimierte, additiv-subtraktive Herstellung von Leichtbau-Strukturbauteilen(2020); Publicationtype: Doctoral Thesis58 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Design guidelines for laser metal deposition of lightweight structures(2018-08-01); The additive manufacturing technology laser metal deposition (LMD) serves a high degree of freedom. For an effective industrial application, it is necessary to identify all advantages and disadvantages. A lowering of the introduction barrier can be achieved with design guidelines helping the engineer early in the product development. With LMD as an additive manufacturing process like selective laser melting (SLM), existing manufacturing guidelines cannot be simply adopted. Due to the complex process constraints, a specific design guideline for LMD has been established. LMD is a layer-by-layer additive manufacturing process that builds parts based on a nozzle-fed powder which is solidified by a laser. The process can be used for surface cladding, repair, and build-up of parts. Different from powder-bed additive technologies, like SLM, the LMD process has different process restrictions. To use the advantages of LMD, the design engineer needs to have knowledge of the limitations of LMD. LMD offers a high degree of freedom in the design of parts and simultaneously offers great potential for weight savings and reduction of manufacturing time. This is especially relevant in lightweight applications, e.g., in the aerospace industry. Complex parts often share simple geometries as a basis. These shapes were identified and used to evaluate the applicability and effectiveness of LMD. Following established lightweight design guidelines, the presented guideline also focuses on fine structures. In addition to the manufacturability, the building accuracy and the surface roughness have been investigated, since both have a significant influence on the product quality and the necessity of post-processing towards the final shape of a part. The results were summarized in a design guideline according to the VDI 2222. This catalog supports the design using LMD as an additive technology.Publicationtype: Journal Article259 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Evolutionary-based optimization strategy in a hybrid manufactured process using LMDWe investigate a hybrid manufacturing strategy combining laser metal deposition (LMD), and milling or turning. LMD is an additive manufacturing process, which can be used for surface cladding, repair, and 3D build-up of parts. One of its advantages is the creation of near net-shape parts on variable ground geometries. The strategy focusses on manufacturing a part by choosing the appropriate wrought material with the remaining volume being added by LMD to minimize used resources and manufacturing time. This is done by adapting an evolutionary algorithm that varies the size, orientation, and position of wrought material with respect to the remaining volume.Publicationtype: Journal ArticleScopus© Citations 4 244 290 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Characterization of the anisotropic properties for laser metal deposited Ti-6Al-4 V(2017-05-01); ; ; ; Laser metal deposition (LMD) connected with milling processes offers the opportunity for an efficient, resource conserving manufacturing for large structural components made from Ti-6Al-4 V. Conventional manufacturing routes for example in the aerospace industry come along with up to 95% of the waste material that has to be machined from the bulk material. LMD is an additive manufacturing process building parts based on nozzle-fed powder by laser solidification. This technology offers unique advantages for the production of near net-shape parts. In contrast to the powder bed-based technologies, it also provides a higher productivity rate. Today, LMD lacks reproducible process strategies manufacturing large parts in narrow tolerances and predictable microstructural properties. The building height of a single layer and the geometrical shape of a three-dimensional shaped part alter progressively with increasing part dimensions, consecutively leading to a higher effort in the manufacturing-process development for such parts. To reduce this effort, in this paper, first the actual state of the anisotropic properties is investigated for LMD-manufactured parts to obtain thorough knowledge of the process and shape-related dependencies with the quality aims. A preliminary experimental investigation of the shape and process-dependent properties such as the microstructure (chemistry changes and grain sizes), mechanical properties (hardness), and geometry (tolerances) is conducted. Based on these results, an in-depth study with optimized parameter sets is carried out to identify the linkage between geometry, process parameters, and the quality criteria of the part, using methods such as light microscopy, inductively coupled plasma-mass spectrometry, Vickers hardness, coordinate measuring, and laser scanning microscopy. For this purpose, representative shaped specimens are manufactured with the LMD-process through different optimized process strategies. The results give the opportunity to evaluate the impact of process parameter changes and the shape on the part quality such as mechanical properties, surface quality, and element loss. This is achieved through identifying the relationship between the input and the output factors from the experimental study, and their importance for part quality is assessed. It is shown that the complex correlation between the process parameters, the part geometry, and the resulting quality can be controlled with suitable process design in LMD-manufacturing of Ti-6Al-4 V parts. Finally, based on the summarized results, an outlook is given on tolerances for different quality aims.Publicationtype: Journal Article151 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Evolutionary-based design and control of geometry aims for AMD-manufacturing of Ti-6Al-4V parts(Elsevier, 2016-09-16); ; ; ; Additive Metal Deposition (AMD) is an additive manufacturing process building parts based on a nozzle-fed powder by laser assisted solidification. The AMD technology offers unique advantages for the production of near net-shape parts. In contrast to the powder bed-based technologies it provides a high productivity grade. Today AMD lacks reproducible process strategies manufacturing large parts in narrow tolerances. The building height of a single layer and the geometrical shape of a whole part alter progressively with increasing part dimensions - consecutively leading to a higher effort in the manufacturing-process development for such parts. To reduce this effort, in this paper first an iterative identification of optimal process parameters is performed by following an evolutionary algorithm under varied BC. Based on the geometry-related parameter sets, tolerances are defined. The process strategies and tolerances are validated for a prototype application considering the defined quality aims. Finally the results are discussed and summarized in an a-priori process design guideline for AMD Ti6Al4V-parts.Publicationtype: Journal ArticleScopus© Citations 15 299 487