Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK

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  • Publication
    Particle contact conditions for cutting edge preparation of micro-milling tools by the immersed tumbling process
    ( 2021)
    Uhlmann, Eckart
    ;
    Polte, Julian
    ;
    Kuche, Yves
    ;
    Landua, Fabian
    For increasing tool life and cutting length of micro-milling tools the cutting edge preparation was successfully established. Using the immersed tumbling process, a reproducible cutting edge preparation with constant cutting edge radii as well as low chipping of the cutting edges can be realised. For a profound understanding of the preparation process and the process mechanisms further knowledge about the particle interactions with cutting tools as well as the particle flow mechanisms needs to be obtained. In this investigation the preparation process of micro-milling tools was analysed and the contact-mechanisms as well as the resulting pressures were investigated by simulation studies. Using the discrete element method (DEM) with the software ROCKY DEM from the company ESSS, Florianópolis, Brasil, the immersed tumbling process could be modelled and particle contacts, particle traces as well as particle interactions with the micro-milling tool can be visualized. Especially the particle-tool interactions were more accurately investigated by analysing the stresses and particles shear work as well as correlations between these parameters to prove the comparability between the process simulation and the real preparation process.
  • Publication
    Reduction of erosion duration for electrical discharge drilling using a nature analogue algorithm with nested strategy types
    ( 2021)
    Uhlmann, Eckart
    ;
    Polte, Mitchel
    ;
    Streckenbach, Jan
    ;
    Osmanovic, Mirsad
    The required high economic efficiency, combined with the corresponding high quality demands, in the aerospace industry as well as in mould and tool making, motivate the necessity of finding suitable parameter combinations for the process of electrical discharge machining (EDM), e.g. when introducing new materials. To counteract this, various methods are being investigated in research for the optimisation of EDM. One new method is the stochastic optimisation procedure evolution strategy (ES). Due to its metaheuristic approach, this optimisation method is excellently suited for very complex processes in which the interrelationship of the individual influencing variables is not known. This publication presents the results of the investigation of the suitability of the ES optimisation method using the example of electrical discharge drilling. For this purpose, two nested ES-types were investigated. The electrode materials used were brass for the tool and stainless steel X5C rNi18-1 for the workpiece. As a result, the erosion duration could be reduced by 30 %. This investigation forms the basis for the use of nested ES types in electrical discharge drilling.
  • Publication
    Simulation and compensation of the thermal behaviour of industrial robots
    ( 2021)
    Uhlmann, Eckart
    ;
    Polte, Julian
    ;
    Mohnke, Christian
    Industrial robot systems offer a flexible, adaptable basis due to their kinematics and their mobility. An influencing variable, which is particularly relevant for processes with long process times tP, is the thermal heating and the associated thermal drift ÎAPt of the tool center point. The maximum deviation from the actual nominal position can reach up to ÎAPt = 1.5 mm. In the investigations, a simulation model for an industrial robot was created and the thermal behaviour was mapped. With this model, the thermal error ÎAPt within the working area can be determined as a function of the current position X and temperature Ï. These data can be used for a targeted correction of the robot path. With the correction by the compensation model the amount of drift for real milling processes could be reduced to a value of ÎAPt = 0.042 mm. The results can help to reduce the influence of thermal heating and the associated thermal drift ÎAPt of the TCP without using cost-intens ive measures with additional hardware and software on external computers for compensating the errors.
  • Publication
    Analysis and recycling of bronze grinding waste to produce maritime components using directed energy deposition
    ( 2021)
    Müller, Vinzenz
    ;
    Marko, Angelina
    ;
    Kruse, Tobias
    ;
    Biegler, Max
    ;
    Rethmeier, Michael
    Additive manufacturing promises a high potential for the maritime sector. Directed Energy Deposition (DED) in particular offers the opportunity to produce large-volume maritime components like propeller hubs or blades without the need of a costly casting process. The post processing of such components usually generates a large amount of aluminum bronze grinding waste. The aim of the presented project is to develop a sustainable circular AM process chain for maritime components by recycling aluminum bronze grinding waste to be used as raw material to manufacture ship propellers with a laser-powder DED process. In the present paper, grinding waste is investigated using a dynamic image analysis system and compared to commercial DED powder. To be able to compare the material quality and to verify DED process parameters, semi-academic sample geometries are manufactured.
  • Publication
    Improved surface generation of multi-material objects in computed tomography using local histograms
    ( 2021)
    Uhlmann, Eckart
    ;
    Hein, Christoph
    ;
    Kayser, Nicolas
    ;
    Dürre, Gregor
    During the last decade industrial computed tomography (iCT) has become one of the most important metrological procedures for internal inspection, where it sees wide-spread use in injection molding and additive manufacturing. Evaluating the CT volume data of multi-material objects represents a major technical challenge. Due to artifacts caused by beam hardening, an over-segmentation of strongly absorbing materials occurs, severely limiting the accuracy of dimensional measurements. The goal of the project presented is the development of an innovative artifact-reduced multi-material segmentation. This is applied to and tested on various complex reconstructed CT data sets. Global approaches show high signal-to-noise-ratio (SNR) but are not able to compensate for local deviations. For smaller volumes the data sets become more consistent, but the SNR decreases due to the reduced data volume. Thus, a more localized approach for the volume image data has the potential to provid e results of higher accuracy. With this newly presented algorithm it is now possible to perform segmentation of all materials, while eliminating over-segmentation errors as well as local noise artifacts almost completely for all tested datasets.
  • Publication
    Production environment of tomorrow (ProMo)
    ( 2021)
    Kuschan, Jan
    ;
    Müller, Vinzenz
    ;
    Monchinger, Stephan
    ;
    Heimann, Oliver
    ;
    Niebuhr, Carsten
    ;
    Kabha, Oday
    Small defects in the grain or major damage to a moulded part or tool can bring production to a standstill. SMEs in particular have neither the personnel nor the equipment to repair such damage on their own, so they send it to specialised contractors. The repair process is carried out manually, depending on the accuracy requirements, and is usually completed by a finishing process. This work requires qualified personnel and, at the same time, requires a lot of time in case of larger damages. In this paper we present a way to map the Maintenance, Repair and Operations (MRO) process chain in a partially automated manner. The symbiosis of individual technologies results in a significantly increased efficiency of the MRO process chain, which continues to focus on people and their process knowledge. While Directed Energy Deposition (DED) for the MRO of moulded parts is used widely, usually a high manual effort in measuring the component geometries and teaching of the machine tool paths is necessary. However, there are clear advantages compared to the manufacture of new parts or manual laser welding repair. At the same time, the resource and energy requirements can often be significantly reduced compared to new part production. ProMo focuses on automating the time-consuming machine programming by reducing the number of necessary work steps in CAD/CAM-based program creation. Based on a subsequent robot-guided scan, a digital actual 3D model is generated. Due to intelligent path planning algorithms, no manual programming of the robot is necessary and at the same time it is possible to detect components of different sizes, shapes and covers in this system with a minimum of effort. In addition, the operator passes on elementary information, such as the approach path of the milling head, to the subsequent processes by means of finger gestures and can thus significantly reduce tedious CAM programming steps. Now, the scanned component is transferred to a 3D-CAD model and a target/actual comparison is created for the damaged areas. Those are milled out in a defined manner and then restored using DED.
  • Publication
    Interaction between capabilities of Model Based Systems Engineering on sensor models
    ( 2021)
    Manoury, Marvin Michael
    ;
    Schmidt, Simon
    ;
    Stark, Rainer
    In modern product development, models are often used for different purposes, e.g., system synthesis, trade-off analysis of system parameters or visualization and creation of design concepts. For some models, this purpose as well as the model itself might change over time. New interactions with the target system can occur and new details are added over time. Both have to be integrated immediately into the development procedure. When models are not maintained up to date and not used by different stakeholders, the benefits of the model-based approach are lessened due to the effort for generation and maintenance. The five development capabilities of MBSE, comprising Systems Environment Analytics (SEA), Systems Definition and Derivation (SDD), Systems Interaction Modeling (SIM), Systems Lifecycle Engineering (SLE) and the MBSE Capability and Maturation Matrix (CMM) address this topic on a capability level.In this article, the authors point out the interaction between these d evelopment capabilities on the example of a Pedestrian Emergency Braking System (PEBS) development in automotive industry, with a focus on sensor models. It will be shown exemplary how one development capability might influence another and how this interaction supports the development of complex systems.
  • Publication
    Towards a Framework for Impact Assessment of Research & Technology Organisations
    ( 2021)
    Kidschun, Florian
    ;
    Hecklau, Fabian
    Due to their ability to bridge the gap between knowledge created by basic research and market requirements, Research and Technology Organisations (RTOs) play a major role in countriesâ innovation systems. Their R&D results should lead to innovations, which in turn generate the economic output of public investment in research and development. Moreover, they should support the foundation of new companies and industrial innovations. RTOs can thus be seen as intermediaries between R&D and the industry, while they themselves constitute to a certain extent entrepreneurs and actors in applied R&D that focus on industrial and commercial application right from the start of their activities. Therewith, RTOs pursue to increase the competitiveness of the entire economy. With a growing demand for evaluating their actual contribution in national innovation systems, simply stating the goal of positive impact to stakeholders like governments, the public, investors etc. is not enough; its accomplishment needs to be proven by robust evidence. In this regard, the value of an impact assessment is determined by the strength of the evidence produced and the credibility of the evaluation. RTOâs research activities and their impacts are diverse in nature and occur across many sectors of the economy. To gain transparent insights into relevant and comprehensive performance metrics showing the impact of RTOs from a micro- and macroeconomic perspective, impacts are only appropriate for evaluation if a causal relationship can be drawn back to their origin. While some impacts are primarily economic and suitable for quantitative analysis, others have to be evaluated qualitatively. Regardless of its type, each impact needs to be assessed within a common framework to enable a comprehensive understanding of RTO's impact. Within this contribution, an impact assessment framework is established with the aim to enable the identification of causal relationships between impacts and their origin.
  • Publication
    Application of tool electrodes oxidised with humid and dry air during the electro-discharge drilling of MAR-M247 alloy
    ( 2021)
    Uhlmann, Eckart
    ;
    Polte, Mitchel
    ;
    Streckenbach, Jan
    ;
    Camin, Bettina
    ;
    Chocholaty, Ondřej
    ;
    Dinh, Ngoc Chuong
    The requirements and challenges of machining advanced materials in the field of aerospace, automotive and tool industry are increasing constantly. Due to their mechanical properties, cutting of high-strength materials such as superalloys is severely limited. Electro-discharge drilling can be used for the manufacturing of holes in hard to machine materials. Although electrical discharge machining (EDM) is successfully applied to the machining of holes in turbine blades, a lack of performance and challenges concerning the geometrical accuracy still remain. By applying inner flushing, the resulting electrically conductive debris is flushed through the lateral working gap, increasing the probability of arcs and short circuits. The resulting increased tool wear, conicity of the hole, limited hole depth and process instabilities are still challenging in electro-discharge drilling. In order to decrease the effects of the arcs and short circuits, a surface modification is appli ed to increase the electrical resistance of the lateral surface of the tool electrode. As a result, the mentioned impairments occur less frequently due to decreased occurrence of arcs and short circuits in the lateral working gap. For the present investigation copper tool electrodes were thermally oxidised in dry and humid air with different durations and used afterwards for electro-discharge drilling of MAR-M247. The tests were carried out on the machine tool AGIETRON Compact 1 from the company GF AgieCharmilles, Losone, Switzerland. Holes with a depth of t = 11 mm were drilled using various surface-modified tool electrodes with a diameter of d = 2 mm. Oxidation with dry air and a extended oxidation time resulted in a 18 % lower erosion duration, accompanied by an increase of the linear wear of the tool electrode Île below 10 %.
  • Publication
    Additive manufacturing of precision cemented carbide parts
    ( 2021)
    Polte, Julian
    ;
    Polte, Mitchel
    ;
    Lahoda, Christian
    ;
    Hocke, Toni
    ;
    Uhlmann, Eckart
    Cemented carbide parts are commonly used as wear resistance components in a broad range of industry, e.g. for forming, mould making and matrices. At state of the art the machining of precision cemented carbide components by milling is strongly limited due to excessive tool wear and long machining times. Promising approaches for precision machining of cemented carbide components are dedicated cutting tool coatings, new cutting materials like binderless polycrystalline diamond and ultrasonic-assisted machining. Nevertheless, for all these approaches the components need to be machined of monolithic materials. The new approach addresses an innovative manufacturing process chain composed of near net shape Additive Manufacturing followed by a precision finishing process. Within this investigations for the manufacturing of precision cemented carbide parts, cemented carbide with a cobalt content of 17 % and a grain size in a range of 23 µm ⤠gs ⤠40 µm were used. As Addit ive Manufacturing technology laser powder bed fusion was used. Diamond slide burnishing and immersed tumbling were investigated as finishing technologies. Based on the investigations, a dedicated process chain for the manufacturing of precision cemented carbide parts could be realised. The findings show that the developed process chain composed of near net shape Additive Manufacturing and the finishing process diamond slide burnishing enables the manufacturing of precision cemented carbide parts with a geometrical accuracy of ag ⤠10 µm. Due to the finishing process the initial surface roughness after Additive Manufacturing could reduce by Ra = 89 %.