Digitala Vetenskapliga Arkivet

Change search
Refine search result
1 - 31 of 31
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Bartkowiak, T.
    et al.
    Poznan University of Technology, Poland.
    Berglund, Johan
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF. Chalmers University of Technology, Sweden.
    Brown, C. A.
    Worcester Polytechnic Institute, USA.
    Establishing functional correlations between multiscale areal curvatures and coefficients of friction for machined surfaces2018In: Surface Topography: Metrology and Properties, ISSN 2051-672X, Vol. 6, no 3, article id 034002Article in journal (Refereed)
    Abstract [en]

    The objective of this research is to determine the strengths of correlation, and their variation with scale, between friction coefficients and topographic characterization parameters, calculated using statistical representations of multiscale areal curvatures. The surfaces are created by milling and manual polishing. Coefficients of friction were measured during bending under tension tests. Surfaces were measured with a white light interferometer. Curvature tensors were calculated using a normal based method adapted for multiscale analysis. Three different regions were analyzed from each of eight samples. Curvature tensor parameters: principal, mean, and Gaussian curvatures were calculated for scales between 0.78 and 47.08 μm. These statistical measures of the curvatures were regressed against the coefficient of friction. Three different analyses were performed, taking into account entire curvature distributions, only negative or positive values and curvatures of top heights. Strong correlations (R2 > 0.85 for many and as large as 0.96) were found for the standard deviations for all four curvature measures when entire distributions were considered. These results suggest that the frictional responses of surfaces could be related to the variance of their topographic curvatures. Average curvature parameters correlate strongly with coefficients of friction for negative values. Curvatures calculated from top regions present strong correlations for both mean and standard deviation of maximal, mean and Gaussian curvatures. This supports the use of multiscale curvature tensor methods for characterizing interactions between surface topography and tribological performance.

  • 2. Bartkowiak, T.
    et al.
    Berglund, Johan
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF.
    Brown, C.A.
    Establishing functional correlations between areal curvature and coefficient of friction for machined surfaces2017Conference paper (Other academic)
  • 3.
    Bartkowiak, Tomasz
    et al.
    Poznan University of Technology, Poland.
    Berglund, Johan
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes. Chalmers University of Technology, Sweden.
    Brown, Christopher
    Worcester Polytechnic Institute, USA.
    Multiscale characterizations of surface anisotropies2020In: Materials, E-ISSN 1996-1944, Vol. 13, no 13, article id 3028Article in journal (Refereed)
    Abstract [en]

    Anisotropy can influence surface function and can be an indication of processing. These influences and indications include friction, wetting, and microwear. This article studies two methods for multiscale quantification and visualization of anisotropy. One uses multiscale curvature tensor analysis and shows anisotropy in horizontal coordinates i.e., topocentric. The other uses multiple bandpass filters (also known as sliding bandpass filters) applied prior to calculating anisotropy parameters, texture aspect ratios (Str) and texture directions (Std), showing anisotropy in horizontal directions only. Topographies were studied on two milled steel surfaces, one convex with an evident large scale, cylindrical form anisotropy, the other nominally flat with smaller scale anisotropies; a EDMed surface, an example of an isotropic surface; and an additively manufactured surface with pillar-like features. Curvature tensors contain the two principal curvatures, i.e., maximum and minimum curvatures, which are orthogonal, and their directions, at each location. Principal directions are plotted for each calculated location on each surface, at each scale considered. Histograms in horizontal coordinates show altitude and azimuth angles of principal curvatures, elucidating dominant texture directions at each scale. Str and Std do not show vertical components, i.e., altitudes, of anisotropy. Changes of anisotropy with scale categorically failed to be detected by traditional characterization methods used conventionally. These multiscale methods show clearly in several representations that anisotropy changes with scale on actual surface measurements with markedly different anisotropies.

  • 4.
    Berglund, Johan
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF.
    Blateyron, François
    Digital Surf, France.
    Using SEM quad BSE images for roughness measurement – calibration of reconstructed surfaces2016Conference paper (Other academic)
  • 5.
    Berglund, Johan
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes. Chalmers University of Technology, Sweden.
    Holmberg, Jonas
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes.
    Wärmefjord, Kristina
    Chalmers University of Technology, Sweden.
    Söderberg, Rikard
    Chalmers University of Technology, Sweden.
    Detailed evaluation of topographical effects of Hirtisation post-processing on electron beam powder bed fusion (PBF-EB) manufactured Ti-6Al-4V component2024In: Precision engineering, ISSN 0141-6359, E-ISSN 1873-2372, Vol. 85, p. 319-327Article in journal (Refereed)
    Abstract [en]

    Metal additive manufacturing surface topographies are complex and challenging to characterise due to e.g. steep local slopes, re-entrant features, varying reflectivity and features of interest in vastly different scale ranges. Nevertheless, average height parameters such as Ra or Sa are commonly used as sole parameters for characterisation. In this paper, a novel method for selecting relevant parameters for evaluation is proposed and demonstrated using a case study where the smoothing effects after three processing steps of the electro chemical post-process Hirtisation of a metal AM surface are quantified. The method uses a combination of conventional areal texture parameters, multiscale analysis and statistics and can be used to efficiently achieve a detailed and more relevant surface topography characterisation. It was found that the three process steps have different effects on the surface topography regarding the types and sizes of features that were affected. In total, Sdq was reduced by 97 %, S5v was reduced by 81 % and Sa was reduced by 78 %. A surface texture with much lower average roughness, less deep pits and less steep slopes was produced, which is expected to be beneficial for improved fatigue properties.

  • 6.
    Berglund, Johan
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF.
    Kjellberg, Mikael
    IUC Olofström, Sweden.
    Liljengren, Magnus
    IUC Olofström, Sweden.
    Kjellsson, Kenneth
    Volvo Cars, Sweden.
    New Test Method for Detection and Analysis of Burrs and Slivers in Trimming and Punching Aluminium Sheet Metal2014Conference paper (Other academic)
    Abstract [en]

     A large problem when trimming or punching aluminium sheet is thecreation of burrs and slivers which degrade the quality of the produced parts. A semiindustrial test for evaluating trimming of aluminium has been further developed toinclude pre-stressing and pre-straining of the sheet material before trimming. Thesemi-industrial test results now show good correlation to industrial productionoutcomes.

    Download full text (pdf)
    fulltext
  • 7.
    Berglund, Johan
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF. Chalmers University of Technology, Sweden.
    Söderberg, Rikard
    Chalmers University of Technology, Sweden.
    Wärmefjord, Kristina
    Chalmers University of Technology, Sweden.
    Industrial needs and available techniques for geometry assurance for metal AM parts with small scale features and rough surfaces2018In: Procedia CIRP, Elsevier B.V. , 2018, p. 131-136Conference paper (Refereed)
    Abstract [en]

    From an industrial perspective this paper aims to explore the state of the art regarding GD&T for metal additive manufacturing, specifically regarding product definition and inspection. The available techniques for geometry assurance for parts with small scale features and rough surfaces are evaluated in terms of suitability for the task and readiness for industrial implementation. It is found that many of the remaining challenges seem to be related to processing of data rather than obtaining data. Current difficulties are related to issues such as calibration, surface determination and defining the most relevant parameters to tolerance and inspect.

  • 8.
    Berglund, Johan
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes. Chalmers University of Technology, Sweden.
    Söderberg, Rikard
    Chalmers University of Technology, Sweden.
    Wärmefjord, Kristina
    Chalmers University of Technology, Sweden.
    Leach, Richard
    University of Nottingham, UK.
    Morse, Edward
    University of North Carolina at Charlotte, USA.
    Functional tolerancing of surface texture - A review of existing methods2020In: Procedia CIRP, Elsevier B.V. , 2020, p. 230-235Conference paper (Refereed)
    Abstract [en]

    Surface texture parameters can provide a link between texture, its processing and function. Recent surveys and industrial experience have shown that the ISO 25178 areal surface texture parameters have not received the level of traction in industry that was predicted when introduced despite the fact that the areal parameters were predicted to have more functionally relevant characterisations than the ISO 4287 profile parameters. The objective of the paper is to enable more functionally relevant specifications of surface texture to be taken up by industry and the scientific community by increasing the knowledge of the ISO 25178 texture and novel feature parameters, and their potential use, as well as knowledge about methods for establishing functionally relevant surface texture specifications. In the paper, existing methods for functional tolerancing of surface texture are reviewed and discussed, examples of applications are given and a direction for continued research is presented. © 2020 The Authors

  • 9.
    Berglund, Johan
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF. Chalmers University of Technology, Sweden.
    Troell, Eva
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF.
    Surface Topography of Nitrided Steel Surfaces2019In: J. Phys.: Conf. Ser.: Conference Series, Institute of Physics Publishing , 2019, Vol. 1183, no 1, article id 012005Conference paper (Refereed)
    Abstract [en]

    The effect of nitrocarburizing were investigated for two different steels, 42CrMo4 and 25CrMo4, with objective to evaluate the influence of initial surface topography on the resulting nitrocarburized surface with regard to surface topography and thickness of the compound layer. It was found that the nitrocarburizing process has an impact on the surface topography. The process creates a short-wave isotropic structure on the original surface and this is particularly evident for the smoother original surfaces. No significant effect on the compound layer thickness depending on the surface topography before heat treatment could be observed. © Published under licence by IOP Publishing Ltd.

  • 10.
    Brown, Christopher. A.
    et al.
    Worcester Polytechnic Institute, USA.
    Hansen, Hans N.
    DTU Technical University of Denmark, Denmark.
    Jiang, Xian J.
    University of Huddersfield, UK.
    Blateyron, Francoise
    Digital Surf, France.
    Berglund, Johan
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF. Chalmers University of Technology, Sweden.
    Senin, Nicola
    University of Nottingham, UK; University of Perugia, Italy.
    Bartkowiak, Tomasz
    Poznan University of Technology, Poland.
    Dixon, Barnali
    University of South Florida, USA.
    Le Goïc, Gaetan
    Université de Bourgogne, France.
    Quinsat, Yann
    ENS Paris Saclay, France.
    Stemp, W. James
    Keene State College, USA.
    Thompson, Mary K.
    GE Additive, USA.
    Ungar, Peter S.
    University of Arkansas, USA.
    Zahouani, E. Hassan
    Ecole Nationale d’Ingénieurs de Saint-Etienne, France.
    Multiscale analyses and characterizations of surface topographies2018In: CIRP annals, ISSN 0007-8506, E-ISSN 1726-0604, Vol. 62, no 2, p. 839-862Article in journal (Refereed)
    Abstract [en]

    This work studies multiscale analyses and characterizations of surface topographies from the engineering and scientific literature with an emphasis on production engineering research and design. It highlights methods that provide strong correlations between topographies and performance or topographies and processes, and methods that can confidently discriminate topographies that were processed or that perform differently. These methods have commonalities in geometric characterizations at certain scales, which are observable with statistics and measurements. It also develops a semantic and theoretical framework and proposes a new system for organizing and designating multiscale analyses. Finally, future possibilities for multiscale analyses are discussed.

  • 11.
    Flys, Olena
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Measurement Technology. Halmstad University, Sweden.
    Berglund, Johan
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes. Chalmers University of Technology, Sweden.
    Rosen, B. -G
    Halmstad University, Sweden.
    Using confocal fusion for measurement of metal AM surface texture2020In: Surface Topography: Metrology and Properties, ISSN 2051-672X, Vol. 8, no 2, article id 024003Article in journal (Refereed)
    Abstract [en]

    The highly complex nature of as printed metal AM surfaces pose other challenges for making measurements compared to surfaces made with many conventional processing methods. The high complexity is caused by high aspect ratios, a mix of high and low reflexivity, steep angles etc. It is not clear which method is the most suitable for measuring these surfaces. The objective of this study was to compare four different measurement modes available in one instrument to evaluate the advantages and drawbacks of the respective techniques regarding measurements of metal AM surfaces. The evaluated measurement modes are Confocal Microscopy, Coherence Scanning Interferometry, Focus Variation and Confocal Fusion. The effect of advantages and drawbacks of studied techniques was tested on typical surfaces produced by L-PBF process. Surfaces printed at 0° and 90° inclinations were compared regarding the measurement results achieved from the different methods. The Power Spectral Density analysis and visual comparison were used for the examination of studied measurements methods. Besides the comparison of areal measurements acquired by different modes available in the instrument also extracted profile measurements were compared with profile images acquired using an Optical Microscope. This study reveals that confocal fusion is a promising technique for AM surface characterisation, due to the highest amount of valid data points in the typical measurement. The new approach developed in the study showed that PSD analysis can be used for evaluation of fill in algorithms incorporated in different software. Results of the profile comparisons help to illustrate features that can be depicted by surface measurements, applying different measurement principles, as well as enables comparison of raw profile data between different types of measurements. Further investigation of measurements on AM surfaces in the frequency domain will bring more understanding about the limitations of measurement techniques. 

  • 12.
    Flys, Olena
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Measurement Technology.
    Johansson, M.
    RISE Research Institutes of Sweden.
    Hosseini, Seyed
    RISE Research Institutes of Sweden, Materials and Production.
    Berglund, Johan
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes.
    Hatami, Sepehr
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes.
    Oikonomou, C.
    Uddeholm AB, Sweden.
    Rosen, B. -G
    Halmstad University, Sweden.
    Heat transfer and flow performance in additively manufactured cooling channels with varying surface topography2020In: Seimitsu Kogaku Kaishi/Journal of the Japan Society for Precision Engineering, ISSN 0912-0289, Vol. 86, no 1, p. 71-79Article in journal (Refereed)
    Abstract [en]

    The flexibility in respect of design and manufacturing freedom that additive manufacturing (AM) offer are key driving factors for many industrial scctors. For example, designing and manufacturing unique internal conformal cooling/heating channels with enhanced functionalities for various applications like tools and heat cxchangcrs. However, for the majority of the metal AM-processes in the as-build condition, AM is associated with high surface roughness, which has a measurable impact e.g on the heat transfer and flow properties. Hence, proper characterization of the fluid flow and heat transfer is vital to understand how the AM surfaces should be optimized for maximum output. The current study considers the cffcct of surface roughness and channels dimensions on the pressure drop and heat transfer. An experimental investigation was made of cooling channels produced by Powdcr-Bcd-Fusion using Lascr-Bcam-Mclting (PBF-LBM) additive manufacturing technique. Cooling channels with as-build surfaces was compared to post-processed cooling channels such as extrude honing and drilled channels, respectively. Results showed the lowest pressure drop for extrude honed channels compare to drilled and as-build channels, while heat transfer showed the same trend for as-build and extrude honed channels. The complexity of surface topography of as-build channels need to be described by parameters suitable for the detection of fluid interaction. Combination of different parameters remains to be investigated.

    Download full text (pdf)
    fulltext
  • 13.
    Forsgren, Lilian
    et al.
    Chalmers University of Technology, Sweden.
    Berglund, Johan
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF, Tillverkningsprocesser. Chalmers University of Technology, Sweden.
    Thunberg, Johannes
    Chalmers University of Technology, Sweden.
    Rigdahl, Mikael
    Chalmers University of Technology, Sweden.
    Boldizar, Antal
    Chalmers University of Technology, Sweden.
    Injection Molding and Appearance of Cellulose-Reinforced Composites2019In: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 60, no 1, p. 5-12Article in journal (Refereed)
    Abstract [en]

    Composite materials based on an ethylene-acrylic acid (EAA) copolymer and 20 wt% cellulose fibers were compounded by two runs in a twin-screw extruder. The composite material with cellulose fibers (CF) and a reference of unfilled EAA were injection molded into plaques using three different temperature profiles with end zone temperatures of 170°C, 200°C, and 230°C. The injection molded samples were then characterized in terms of their mechanical properties, thermal properties, appearance (color and gloss), and surface topography. The higher processing temperatures resulted in a clear discoloration of the composites, but there was no deterioration in the mechanical performance. The addition of cellulose typically gave a tensile modulus three times higher than that of the unfilled EAA, but the strength and strain at rupture were reduced when fibers were added. The processing temperature had no significant influence on the mechanical properties of the composites. Gloss measurements revealed negligible differences between the samples molded at the different melt temperatures but the surface smoothness was somewhat higher when the melt temperature was increased. In general, addition of the cellulose to the EAA reduced the gloss level and the surface smoothness.

  • 14.
    Holmberg, Jonas
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes.
    Berglund, Johan
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes.
    Brohede, Ulrika
    Swerim AB, Sweden.
    Åkerfeldt, Pia
    Luleå university of Technolgy, Sweden.
    Sandell, Viktor
    Luleå university of Technology, Sweden.
    Rashid, Amir
    KTH Royal institute of Technology, Sweden.
    Zhao, Xiaoyu
    KTH Royal institute of Technology, Sweden.
    Dadbakhsh, Sasan
    KTH Royal institute of Technology, Sweden.
    Fischer, Marie
    Chalmers university of Technology, Sweden.
    Hryha, Eduard
    Chalmers university of Technology, Sweden.
    Wiklund, Urban
    Uppsala university, Sweden.
    Hassila, Carl Johan Karlsson
    Uppsala university, Sweden.
    Hosseini, Seyed
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes.
    Machining of additively manufactured alloy 718 in as-built and heat-treated condition: surface integrity and cutting tool wear2023In: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 130, no 3-4, p. 1823-1842Article in journal (Refereed)
    Abstract [en]

    Additive manufacturing (AM) using powder bed fusion is becoming a mature technology that offers great possibilities and design freedom for manufacturing of near net shape components. However, for many gas turbine and aerospace applications, machining is still required, which motivates further research on the machinability and work piece integrity of additive-manufactured superalloys. In this work, turning tests have been performed on components made with both Powder Bed Fusion for Laser Beam (PBF-LB) and Electron Beam (PBF-EB) in as-built and heat-treated conditions. The two AM processes and the respective heat-treatments have generated different microstructural features that have a great impact on both the tool wear and the work piece surface integrity. The results show that the PBF-EB components have relatively lower geometrical accuracy, a rough surface topography, a coarse microstructure with hard precipitates and low residual stresses after printing. Turning of the PBF-EB material results in high cutting tool wear, which induces moderate tensile surface stresses that are balanced by deep compressive stresses and a superficial deformed surface that is greater for the heat-treated material. In comparison, the PBF-LB components have a higher geometrical accuracy, a relatively smooth topography and a fine microstructure, but with high tensile stresses after printing. Machining of PBF-LB material resulted in higher tool wear for the heat-treated material, increase of 49%, and significantly higher tensile surface stresses followed by shallower compressive stresses below the surface compared to the PBF-EB materials, but with no superficially deformed surface. It is further observed an 87% higher tool wear for PBF-EB in as-built condition and 43% in the heat-treated condition compared to the PBF-LB material. These results show that the selection of cutting tools and cutting settings are critical, which requires the development of suitable machining parameters that are designed for the microstructure of the material.

    Download full text (pdf)
    fulltext
  • 15.
    Holmberg, Jonas
    et al.
    RISE Res Inst Sweden AB, Dept Mfg Proc, Argongatan 30, Mölndal, Sweden..
    Berglund, Johan
    RISE Res Inst Sweden AB, Dept Mfg Proc, Argongatan 30, Mölndal, Sweden..
    Brohede, Ulrika
    Swerim AB, Dept Prod Technol, Isafjordsgatan 28A, Kista, Sweden..
    Åkerfeldt, Pia
    Luleå Univ Technol, Div Mat Sci, SE-97187 Luleå, Sweden..
    Sandell, Viktor
    Luleå Univ Technol, Div Mat Sci, SE-97187 Luleå, Sweden..
    Rashid, Amir
    KTH Royal Inst Technol, Dept Prod Engn, Brinellvagen 68, SE-10044 Stockholm, Sweden..
    Zhao, Xiaoyu
    KTH Royal Inst Technol, Dept Prod Engn, Brinellvagen 68, SE-10044 Stockholm, Sweden..
    Dadbakhsh, Sasan
    KTH Royal Inst Technol, Dept Prod Engn, Brinellvagen 68, SE-10044 Stockholm, Sweden..
    Fischer, Marie
    Chalmers Univ Technol, Dept Ind & Mat Sci, Horsalsvagen 7B, Gothenburg, Sweden..
    Hryha, Eduard
    Chalmers Univ Technol, Dept Ind & Mat Sci, Horsalsvagen 7B, Gothenburg, Sweden..
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Karlsson Hassila, Carl Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Applied Material Science.
    Hosseini, Seyed
    RISE Res Inst Sweden AB, Dept Mfg Proc, Argongatan 30, Mölndal, Sweden..
    Machining of additively manufactured alloy 718 in as-built and heat-treated condition: surface integrity and cutting tool wear2024In: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 130, p. 1823-1842Article in journal (Refereed)
    Abstract [en]

    Additive manufacturing (AM) using powder bed fusion is becoming a mature technology that offers great possibilities and design freedom for manufacturing of near net shape components. However, for many gas turbine and aerospace applications, machining is still required, which motivates further research on the machinability and work piece integrity of additive-manufactured superalloys. In this work, turning tests have been performed on components made with both Powder Bed Fusion for Laser Beam (PBF-LB) and Electron Beam (PBF-EB) in as-built and heat-treated conditions. The two AM processes and the respective heat-treatments have generated different microstructural features that have a great impact on both the tool wear and the work piece surface integrity. The results show that the PBF-EB components have relatively lower geometrical accuracy, a rough surface topography, a coarse microstructure with hard precipitates and low residual stresses after printing. Turning of the PBF-EB material results in high cutting tool wear, which induces moderate tensile surface stresses that are balanced by deep compressive stresses and a superficial deformed surface that is greater for the heat-treated material. In comparison, the PBF-LB components have a higher geometrical accuracy, a relatively smooth topography and a fine microstructure, but with high tensile stresses after printing. Machining of PBF-LB material resulted in higher tool wear for the heat-treated material, increase of 49%, and significantly higher tensile surface stresses followed by shallower compressive stresses below the surface compared to the PBF-EB materials, but with no superficially deformed surface. It is further observed an 87% higher tool wear for PBF-EB in as-built condition and 43% in the heat-treated condition compared to the PBF-LB material. These results show that the selection of cutting tools and cutting settings are critical, which requires the development of suitable machining parameters that are designed for the microstructure of the material.

    Download full text (pdf)
    FULLTEXT01
  • 16.
    Holmberg, Jonas
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes.
    Berglund, Johan
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes.
    Stormvinter, Albin
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes.
    Andersson, Pär
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes.
    Lundin, Per
    Ludin Stress Service AB, Sweden.
    Influence of Local Electropolishing Conditions on Ferritic–Pearlitic Steel on X-Ray Diffraction Residual Stress Profiling2024In: Journal of materials engineering and performance (Print), ISSN 1059-9495, E-ISSN 1544-1024, Vol. 33, p. 3682-Article in journal (Refereed)
    Abstract [en]

    Layer removal with electropolishing is a well-established method when measuring residual stress profiles with lab-XRD. This is done to measure the depth impact from processes such as shot peening, heat treatment, or machining. Electropolishing is used to minimize the influence on the inherent residual stresses of the material during layer removal, performed successively in incremental steps to specific depths followed by measurement. Great control of the material removal is critical for the measured stresses at each depth. Therefore, the selection of size of the measurement spot and electropolishing parameters is essential. The main objective in this work is to investigate how different electrolytes and electropolishing equipment affect the resulting surface roughness, geometry, microstructure, and consequently the measured residual stress. A second objective has been to establish a methodology of assessing the acquired electropolished depth. The aim has been to get a better understanding of the influence of the layer removal method on the accuracy of the acquired depth. Evaluation has been done by electropolishing one ground and one shot peened sample of a low-alloy carbon steel, grade 1.1730, with different methods. The results showed a difference in stresses depending on the electrolyte used where the perchloric acid had better ability to retain the stresses compared to the saturated salt. Electropolishing with saturated salt is fast and results in evenly distributed material removal but has high surface roughness, which is due to a difference in electropolishing of the two phases, ferrite, and pearlite. Perchloric acid electropolishing is slower but generates a smooth surface as both ferrite and pearlite have the same material removal rates but may cause an increased material removal for the center of the electropolished area. In this work, it is suggested to use perchloric acid electropolishing for the final layer removal step. © 2023, The Author(s).

  • 17.
    Holmberg, Jonas
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF.
    Berglund, Johan
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF.
    Wretland, Anders
    GKN Aerospace Sweden AB, Sweden.
    Beno, Tomas
    University West, Sweden.
    Evaluation of surface integrity after high energy machining with EDM, laser beam machining and abrasive water jet machining of alloy 7182019In: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 100, no 5-8, p. 1575-1591Article in journal (Refereed)
    Abstract [en]

    Development of future aero engine components based on new design strategies utilising topological optimisation and additive manufacturing has in the past years become a reality. This allows for designs that involve geometries of “free form” surfaces and material combinations that could be difficult to machine using conventional milling. Hence, alternative manufacturing routes using non-conventional high energy methods are interesting to explore. In this investigation, the three high energy machining methods abrasive water jet machining (AWJM), electrical discharge machining (EDM) and laser beam machining (LBM) have been compared in terms of surface integrity to the reference, a ball nosed end milled surface. The results showed great influence on the surface integrity from the different machining methods. It was concluded that AWJM resulted in the highest quality regarding surface integrity properties with compressive residual stresses in the surface region and a low surface roughness with texture from the abrasive erosion. Further, it was shown that EDM resulted in shallow tensile residual stresses in the surface and an isotropic surface texture with higher surface roughness. However, even though both methods could be considered as possible alternatives to conventional milling they require post processing. The reason is that the surfaces need to be cleaned from either abrasive medium from AWJM or recast layer from EDM. It was further concluded that LBM should not be considered as an alternative in this case due to the deep detrimental impact from the machining process. © 2018, The Author(s).

  • 18.
    Holmberg, Jonas
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes.
    Berglund, Johan
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes.
    Wretland, Anders
    GKN Aerospace Engine Systems AB, Sweden.
    Klason, Anki
    Hanza Mechanics Sweden AB, Sweden.
    Persson, Roger
    Hanza Mechanics Sweden AB, Sweden.
    Milling or grinding for manufacturing of an Alloy 718 gas turbine component?: – A comparison of surface integrity and productivity2024In: Procedia CIRP, E-ISSN 2212-8271, Vol. 123, p. 7-12Article in journal (Refereed)
    Abstract [en]

    Milling is traditionally the most used machining method when manufacturing complex gas turbine components. In particular those made from nickel-based superalloys. However, for larger free form surfaces, grinding may be an efficient alternative that could be used throughout the complete manufacturing route, from roughing to finishing. Hence, in this work the two processing methods has been compared in regard to surface integrity and productivity. Machining tests have been performed on case plates of heat-treated Alloy 718 using best practise setting for roughing and finishing with grinding and milling. The surface integrity of the work pieces was evaluated regarding surface topography, residual stresses, and deformation. This comparison showed that the main advantage with grinding is the ability to switch between roughing and finishing by just altering the depth of cut. Further, grinding offers lower surface roughness, compressive residual stresses, and significantly lower degree of deformation. From a productivity perspective, deep grinding may offer high material removal rates and ability to machine several work pieces in the same setup. However, grinding is limited to simpler free form geometries and may result in minor surface damages and abrasive surface residue. For selection of machining strategy, advantages and drawbacks shown in this work need to be considered for the application at hand in respect to productivity, surface integrity and requirements on fatigue life.

    Download full text (pdf)
    fulltext
  • 19.
    Holmberg, Jonas
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF.
    Rodri­guez Prieto, Juan Manuel
    Luleå University of Technology, Sweden.
    Berglund, Johan
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF.
    Sveboda, Ales
    Luleå University of Technology, Sweden.
    Jonsén, Pär
    Luleå University of Technology, Sweden.
    Experimental and PFEM-simulations of residual stresses from turning tests of a cylindrical Ti-6Al-4V shaft2018In: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 71, p. 144-149Article in journal (Refereed)
    Abstract [en]

    Alloy Ti-6Al-4V is a frequently used material in aero space applications due the high strength and low weight. This material is however often considered as a difficult to machine alloy due to several material properties such as the inherent characteristics of high hot hardness and strength which is causing an increased deformation of the cutting tool during machining. The thermal properties also cause a low thermal diffusion from locally high temperatures in the cutting zone that allows for reaction to the tool material resulting in increased tool wear. Predicting the behavior of machining of this alloy is therefore essential when selecting machining tools or machining strategies. If the surface integrity is predicted, the influence of different machining parameters could be studied using Particle Finite Element (PFEM)-simulations. In this investigation the influence from cutting speed and feed during turning on the residual stresses has been measured using x-ray diffraction and compared to PFEM-simulations. The results showed that cutting speed and feed have great impact on the residual stress state. The measured cutting force showed a strong correlation especially to the cutting feed. The microstructure, observed in SEM, showed highly deformed grains at the surface from the impact of the turning operation and the full width half maximum from the XDR measurements distinguish a clear impact from different cutting speed and feed which differed most for the higher feed rate. The experimental measurements of the residual stresses and the PFEM simulations did however not correlate. The surface stresses as well as the sign of the residuals stresses differed which might be due to the material model used and the assumption of using a Coulomb friction model that might not represent the cutting conditions in the investigated case. © 2018 Elsevier B.V. All rights reserved.

    Download full text (pdf)
    fulltext
  • 20.
    Holmberg, Jonas
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF, Tillverkningsprocesser. University West, Sweden.
    Steuwer, Axel
    Nelson Mandela Metropolitan University, South Africa.
    Stormvinter, Albin
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF, Tillverkningsprocesser.
    Kristoffersen, Hans
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF, Tillverkningsprocesser.
    Haakanen, Marja
    Stresstech OY, Finland.
    Berglund, Johan
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF, Tillverkningsprocesser.
    Residual stress state in an induction hardened steel bar determined by synchrotron- and neutron diffraction compared to results from lab-XRD2016In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 667, p. 199-207Article in journal (Refereed)
    Abstract [en]

    Induction hardening is a relatively rapid heat treatment method to increase mechanical properties of steel components. However, results from FE-simulation of the induction hardening process show that a tensile stress peak will build up in the transition zone in order to balance the high compressive stresses close to the surface. This tensile stress peak is located in the transition zone between the hardened zone and the core material. The main objective with this investigation has been to non-destructively validate the residual stress state throughout an induction hardened component. Thereby, allowing to experimentally confirming the existence and magnitude of the tensile stress peak arising from rapid heat treatment. For this purpose a cylindrical steel bar of grade C45 was induction hardened and characterised regarding the microstructure, hardness, hardening depth and residual stresses. This investigation shows that a combined measurement with synchrotron/neutron diffraction is well suited to non-destructively measure the strains through the steel bar of a diameter of 20 mm and thereby making it possible to calculate the residual stress profile. The result verified the high compressive stresses at the surface which rapidly changes to tensile stresses in the transition zone resulting in a large tensile stress peak. Measured stresses by conventional lab-XRD showed however that at depths below 1.5 mm the stresses were lower compared to the synchrotron and neutron data. This is believed to be an effect of stress relaxation from the layer removal. The FE-simulation predicts the depth of the tensile stress peak well but exaggerates the magnitude compared to the measured results by synchrotron/neutron measurements. This is an important knowledge when designing the component and the heat treatment process since this tensile stress peak will have great impact on the mechanical properties of the final component.

  • 21.
    Holmberg, Jonas
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes.
    Wretland, Anders
    GKN Aerospace Engine Systems AB, Sweden.
    Berglund, Johan
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes.
    Abrasive Water Jet Milling as An Efficient Manufacturing Method for Superalloy Gas Turbine Components2022In: Journal of Manufacturing and Materials Processing, ISSN 2504-4494, Vol. 6, no 5, article id 124Article in journal (Refereed)
    Abstract [en]

    In order to improve efficiency when manufacturing gas turbine components, alternative machining techniques need to be explored. In this work, abrasive water jet (AWJ) machining by milling has been investigated as an alternative to traditional milling. Various test campaigns have been conducted to show different aspects of using AWJ milling for the machining of superalloys, such as alloy 718. The test campaigns span from studies of individual AWJ-milled tracks, multi-pass tracks, and the machining of larger components and features with complex geometry. In regard to material removal rates, these studies show that AWJ milling is able to compete with traditional semi/finish milling but may not reach as high an MRR as rough milling when machining in alloy 718. However, AWJ milling requires post-processing which decreases the total MRR. It has been shown that a strong advantage with AWJ milling is to manufacture difficult geometries such as narrow radii, holes, or sharp transitions with kept material removal rates and low impact on the surface integrity of the cut surface. Additionally, abrasive water jet machining (AWJM) offers a range of machining possibilities as it can alter between cutting through and milling. The surface integrity of the AWJM surface is also advantageous as it introduces compressive residual stress but may require post-processing to meet similar surface roughness levels as traditional milling and to remove unwanted AWJM particles from the machined surface. © 2022 by the authors.

  • 22.
    Holmberg, Jonas
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF. University Wes, Sweden.
    Wretland, Anders
    GKN Aerospace Sweden AB, Sweden.
    Berglund, Johan
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF.
    Grit Blasting for Removal of Recast Layer from EDM Process on Inconel 718 Shaft: An Evaluation of Surface Integrity2016In: Journal of materials engineering and performance (Print), ISSN 1059-9495, E-ISSN 1544-1024, Vol. 25, no 12, p. 5540-5550Article in journal (Refereed)
    Abstract [en]

    The heat generated during EDM melts the work material and thereby allows large amounts to be removed, but an unfavorable surface of a recast layer (RCL) will also be created. This layer has entirely different properties compared to the bulk. Hence, it is of great interest to efficiently remove this layer and to verify that it has been removed. The main objective of this work has been to study the efficiency of grit blasting for removal of RCL on an EDM aero space shaft. Additionally, x-ray fluorescence (XRF) has been evaluated as a nondestructive measurement to determine RCL presence. The results show that the grit-blasting processing parameters have strong influence on the ability to remove RCL and at the same time introduce beneficial compressive stresses even after short exposure time. Longer exposure will remove the RCL from the surface but also increase the risk that a larger amount of the blasting medium will get stuck into the surface. This investigation shows that a short exposure time in combination with a short grit-blasting nozzle distance is the most preferable process setting. It was further found that handheld XRF equipment can be used as a nondestructive measurement in order to evaluate the amount of RCL present on an EDM surface. This was realized by analyzing the residual elements from the EDM wire.

    Download full text (pdf)
    fulltext
  • 23.
    Holmberg, Jonas
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes. University West, Sweden.
    Wretland, Anders
    GKN Aerospace Sweden AB, Sweden.
    Berglund, Johan
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes.
    Beno, Tomas
    University West, Sweden.
    A detailed investigation of residual stresses after milling Inconel 718 using typical production parameters for assessment of affected depth2020In: Materials Today Communications, ISSN 2352-4928, Vol. 24, article id 100958Article in journal (Refereed)
    Abstract [en]

    Production of superalloy gas turbine parts involves time consuming milling operations typically performed in a sequence from rough to finish milling. Rough milling using ceramic inserts allows high removal rates but causes severe sub-surface impact. A relatively large allowance is therefore left for subsequent cemented carbide milling. With increased knowledge of the affected depth it will be possible to reduce the machining allowance and increase efficiency of the manufacturing process. Milling Inconel 718 using typical production parameters has been investigated using new and worn ceramic and cemented carbide inserts. Residual stresses in a milled slot were measured by x-ray diffraction. Stresses were measured laterally across the slot and below the surface, to study the depth affected by milling. The most important result from this work is the development of a framework concerning how to evaluate the affected depth for a milling operation. The evaluation of a single milled slot shows great potential for determining the optimum allowance for machining. Our results show that the residual stresses are greatly affected by the ceramic and cemented carbide milling; both regarding depth as well as distribution across the milled slot. It has been shown that it is important to consider that the stresses across a milled slot are the highest in the center of the slot and gradually decrease toward the edges. Different inserts, ceramic and cemented carbide, and tool wear, alter how the stresses are distributed across the slot and the affected depth.

  • 24.
    Holmberg, Jonas
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes. University West, Sweden.
    Wretland, Anders
    GKN Aerospace Sweden AB, Sweden.
    Berglund, Johan
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes.
    Beno, Tomas
    University West, Sweden.
    Selection of milling strategy based on surface integrity investigations of highly deformed Alloy 718 after ceramic and cemented carbide milling2020In: Journal of Manufacturing Processes, ISSN 1526-6125, Vol. 58, p. 193-207Article in journal (Refereed)
    Abstract [en]

    High speed milling with ceramic indexable inserts is a current practice for manufacturing of gas turbine components in superalloys since it allows for high material removal rates. Ceramic milling is used for rough milling, which is followed by cemented carbide semi- and finish milling. The tool motion play an important role on the resulting surface integrity. The machining strategy of up or down milling will induce different degree of residual stresses and deformations. Increased knowledge of selecting the machining strategy with lowest impact will promote improved productivity by using ceramic milling to a greater extent based on the affected depth. The main objective in this work has been to correlate the residual stresses and deformations to promote a greater utilization of ceramic milling while still producing surfaces with acceptable properties. Prior investigations have shown that ceramic milling induce very high tensile stresses in the surface, exceeding the material's nominal yield strength. A second objective has been to explain these stress levels by thorough investigations of the deformation after milling. In this study, milling tests with new and worn ceramic and cemented carbide inserts have been performed in Alloy 718. The topography, residual stresses, deformation and hardness have been investigated for up, centre and down milling. Residual stress measurements were performed using X-ray diffraction, followed by evaluation of hardness and deformation, using hardness testing, light optical microscopy as well as electron back scattering diffraction (EBSD). These results have been used to determine an appropriate milling strategy based on lowest possible impact in respect to residual stresses and deformation. The results show a high degree of deformation after milling that differs for the up, centre and down milling. Based on these results, it is shown that up milling is preferable for new inserts but as the inserts wear out, down milling becomes more suitable since a lower degree of deformation and residual stress impact was observed. EBSD and hardness testing showed that the milling, especially ceramic milling, caused severe deformation of the surfaces resulting in grain refinement to a nano-crystalline level. This is most likely the explanation for the prevalence of the high tensile stresses without distorting or causing failure. © 2020 The Authors

  • 25.
    Holmberg, Jonas
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF. University West, Sweden.
    Wretland, Anders
    GKN Aerospace Sweden AB, Sweden.
    Berglund, Johan
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF.
    Beno, Tomas
    University West, Sweden.
    Surface integrity after post processing of EDM processed Inconel 718 shaft2018In: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 95, no 5-8, p. 2325-2337Article in journal (Refereed)
    Abstract [en]

    Electrical discharge machining (EDM) is considered as an efficient alternative to conventional material removal concepts that allows for much higher material removal rates. However, EDM generates unwanted features such as re-cast layer (RCL), tensile residual stresses and a rough surface. In order to recover the surface integrity, different post processes has been compared: high-pressure water jet (HPWJ), grit blasting (GB) and shot peening (SP). Surface integrity has been evaluated regarding microstructure, residual stresses, chemical content and surface roughness. The results showed that a combination of two post processes is required in order to restore an EDM processed surface of discontinuous islands of RCL. HPWJ was superior for removing RCL closely followed by grit blasting. However, grit blasting showed embedded grit blasting abrasive into the surface. Regarding surface roughness, it was shown that both grit blasting and HPWJ caused a roughening of the surface topography while shot peening generates a comparably smoother surface. All three post processes showed compressive residual stresses in the surface where shot peening generated the highest amplitude and penetration depths. However, the microstructure close to the surface revealed that shot peening had generated cracks parallel to the surface. The results strongly state how important it is to evaluate the surface at each of the different subsequent process steps in order to avoid initiation of cracks. © 2017 The Author(s)

  • 26.
    Holmberg, Jonas
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes.
    Wretland, Anders
    GKN Aerospace Sweden AB, Sweden.
    Berglund, Johan
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes.
    Beno, Tomas
    University West, Sweden.
    Karlsson, Anton
    Tooltec Trestad AB, Sweden.
    Surface integrity investigation to determine rough milling effects for assessment of machining allowance for subsequent finish milling of alloy 7182021In: Journal of Manufacturing and Materials Processing, ISSN 2504-4494, Vol. 5, no 2, article id 48Article in journal (Refereed)
    Abstract [en]

    The planned material volume to be removed from a blank to create the final shape of a part is commonly referred to as allowance. Determination of machining allowance is essential and has a great impact on productivity. The objective of the present work is to use a case study to investigate how a prior rough milling operation affects the finish machined surface and, after that, to use this knowledge to design a methodology for how to assess the machining allowance for subsequent milling operations based on residual stresses. Subsequent milling operations were performed to study the final surface integrity across a milled slot. This was done by rough ceramic milling followed by finish milling in seven subsequent steps. The results show that the up-, centre and down-milling induce different stresses and impact depths. Employing the developed methodology, the depth where the directional influence of the milling process diminishes has been shown to be a suitable minimum limit for the allowance. At this depth, the plastic flow causing severe deformation is not present anymore. It was shown that the centre of the milled slot has the deepest impact depth of 500 µm, up-milling caused an intermediate impact depth of 400 µm followed by down milling with an impact depth of 300 µm. With merged envelope profiles, it was shown that the effects from rough ceramic milling are gone after 3 finish milling passes, with a total depth of cut of 150 µm. © 2021 by the authors. 

  • 27.
    Holmberg, Jonas
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes. University West, Sweden.
    Wretland, Anders
    GKN Aerospace Engine System Sweden AB, Sweden.
    Hammersberg, Peter
    Chalmers University of Technology, Sweden.
    Berglund, Johan
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes.
    Suárez, Alfredo
    Tecnalia R&T, Spain.
    Beno, Tomas
    University West, Sweden.
    Surface integrity investigations for prediction of fatigue properties after machining of alloy 7182021In: International Journal of Fatigue, ISSN 0142-1123, E-ISSN 1879-3452, Vol. 144, article id 106059Article in journal (Refereed)
    Abstract [en]

    Fatigue performance is crucial for gas turbine components, and it is greatly affected by the manufacturing processes. Ability to predict the expected fatigue life of a component based on surface integrity has been the objective in this work, enabling new processing methods. Alloy 718 samples were prepared by different machining setups, evaluated in fatigue testing and surface integrity investigations. These results generated two predictive statistical multi-variate regression models. The fatigue correlated well with roughness, residual stresses and deformation. The two models showed great potential, which encourages further exploration to fine-tune the procedure for the particular case. © 2020 The Authors

  • 28.
    Krishna, Amogh Vedantha
    et al.
    Halmstad University, Sweden.
    Flys, Olena
    RISE Research Institutes of Sweden, Safety and Transport, Measurement Technology. Halmstad University, Sweden.
    Reddy, Vijeth
    Halmstad University, Sweden.
    Berglund, Johan
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes. Chalmers University of Technology, Sweden.
    Rosen, B. -G
    Halmstad University, Sweden.
    Areal surface topography representation of as-built and post-processed samples produced by powder bed fusion using laser beam melting2020In: Surface Topography: Metrology and Properties, ISSN 2051-672X, Vol. 8, no 2, article id 024012Article in journal (Refereed)
    Abstract [en]

    The increasing interest in Additive Manufacturing (AM) is due to its huge advantage in producing parts without any geometrical limitations. It is due to this reason, AM is extensively utilized in automotive, aerospace, medical and dental applications. Despite their popularity, AM is often associated with inferior surface quality which is one of the many reasons why it has failed to fully replace traditional methods. Hence, AM is always followed by a subsequent post-processing step to produce the end-product. To establish control over the surface quality it is first necessary to fully understand the surface behaviour concerning the factors affecting it. In this paper, the focus is mainly on having a better understanding of the surfaces by using scale-sensitive fractal analysis. In addition, the paper documents the influence of build inclination and post-processing in particular shot blasting on surface topography and utilizes a multi-scale approach to identify the most important scale and parameters for characterization. Results of this study reveal that shot blasting has a minimalistic effect on surface features at a large scale as it cannot remove the waviness completely. At smaller scales, blasting imparts additional features on the surface due to the impact of abrasive particles at high pressure. At the intermediate scales, the influence of shot blasting is highest as it successfully eliminates the surface features comprising of partially melted powder particles and stair-step effect.

  • 29.
    Kurdve, Martin
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Product Realisation Methodology. Chalmers University of Technology, Sweden .
    Persson, Karl-Eric
    RISE Research Institutes of Sweden, Materials and Production, Product Realisation Methodology.
    Widfeldt, Magnus
    RISE Research Institutes of Sweden, Materials and Production, Product Realisation Methodology.
    Berglund, Johan
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes. Chalmers University of Technology, Sweden .
    Drott, Alexander
    Volvo, Sweden.
    Lead-Time Effect Comparison of Additive Manufacturing with Conventional Alternatives2020In: Advances in Transdisciplinary Engineering at SPS2020, IOS Press BV , 2020, p. 672-679Conference paper (Refereed)
    Abstract [en]

    This single case study used value stream mapping as input data to analyse alternatives for production of quenching tools in an on-site tool department of an automotive manufacturer. The existing manufacturing organised as a functional workshop was compared to the alternatives, adding an additive manufacturing cell or a conventional automated cell, with regards to lead-Time and needed process changes. The results indicate that lead-Time savings should not be the only reason for considering additive manufacturing. When it is beneficial for design and product functionality improvements, however, lead time improvements may give a contribution to the business case. © 2020 The authors

  • 30.
    López, Alvaro
    et al.
    KTH Royal Institute of Technology, Sweden.
    Berglund, Johan
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes.
    Marteleur, Klas
    Cytiva, Sweden.
    Finne-Wistrand, Anna
    KTH Royal Institute of Technology, Sweden.
    Impact of storage at different thermal conditions on surface characteristics of 3D printed polycaprolactone and poly(ε-caprolactone-co-p-dioxanone) scaffolds2023In: Bioprinting, ISSN 2405-8866, Vol. 33, article id e00293Article in journal (Refereed)
    Abstract [en]

    Fused filament fabrication (FFF) is a commonly used method for producing three-dimensional scaffolds using synthetic, degradable polymers. However, there are several variables that must be considered when fabricating devices for clinical use, one of which is storage conditions after printing. While the academic community has examined the impact of FFF on mechanical and thermal properties, there has been less focus on how storage conditions would affect the surface texture of scaffolds. Our hypothesis was that the surface, thermal and physical properties of FFF scaffolds are significantly influenced by the storage conditions. We evaluated the surfaces of FFF poly (ε-caprolactone) (PCL) and poly (ε-caprolactone-co-p-dioxanone) (PCLDX) strands that were stored at 4 °C, 20 °C, and 37 °C for 28 days. We monitored surface texture, physical and thermal changes to understand the effect of storage on the strands. The implementation of scale-sensitive fractal analysis and feature parameters revealed that storage conditions at 37 °C increased the number of hills and dales, as well as the density of peaks and pits compared to 20 °C and 4 °C, for both materials. The feature roughness parameters for PCL had up to 90% higher values than those of PCLDX, which correlated with the physical and thermal properties of the materials. These differences may impact further surface-cell interaction, highlighting the need for further evaluation for faster clinical translation. Our findings emphasize the importance of considering storage conditions in the design and manufacture of FFF scaffolds and suggest that the use of feature roughness parameters could facilitate the optimization and tailoring the surface properties for specific applications. © 2023 The Authors

  • 31.
    Yuan, M.
    et al.
    Chalmers University of Technology, Sweden.
    Cao, Y.
    Chalmers University of Technology, Sweden; Central South University, China.
    Karamchedu, S.
    Uddeholms AB, Sweden.
    Hosseini, Seyed
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes. Chalmers University of Technology, Sweden.
    Yao, Y.
    Chalmers University of Technology, Sweden.
    Berglund, Johan
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes. Chalmers University of Technology, Sweden.
    Liu, L.
    Central South University, China.
    Nyborg, L.
    Chalmers University of Technology, Sweden.
    Characteristics of a modified H13 hot-work tool steel fabricated by means of laser beam powder bed fusion2022In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 831, article id 142322Article in journal (Refereed)
    Abstract [en]

    In the present study, a modified H13 hot-work tool steel (M-H13) was fabricated by laser beam powder bed fusion (LB-PBF). The effect of two types of post processing, direct tempering from as-built condition (DT) and conventional quenching followed by tempering (QT), on the microstructure and mechanical properties was evaluated. The typical microstructure in QT condition was tempered martensite with carbides along lath boundaries. In DT condition, melt pool boundaries and cellular structure from as-built condition were still observed. While comparable tensile properties and hardness were obtained, DT samples exhibited significantly lower impact toughness compared to QT samples. This was attributed to the difference in work hardening ability and strain rate sensitivity originating from different microstructures obtained under these two heat treatment conditions. The study was also focused on the softening behavior and the correlation with the microstructure of the two post treatments at the elevated temperatures. It was found that the DT samples showed lower thermal softening compared to QT samples. The evolution of carbides was discussed based on the microanalysis results and the JMatPro simulation. © 2021 The Authors

1 - 31 of 31
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf