| 1. |
- Berglund, Johan C, 1978, et al.
(författare)
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Detailed evaluation of topographical effects of Hirtisation post-processing on electron beam powder bed fusion (PBF-EB) manufactured Ti-6Al-4V component
- 2024
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Ingår i: Precision Engineering. - : Elsevier Inc.. - 0141-6359 .- 1873-2372. ; 85, s. 319-327
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 2. |
- Cabanettes, Frédéric, 1982-, et al.
(författare)
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Roughness variations in cylinder liners induced by honing tools’ wear
- 2015
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Ingår i: Precision engineering. - Philadelphia, PA : Elsevier. - 0141-6359 .- 1873-2372. ; 41, s. 40-46
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Tidskriftsartikel (refereegranskat)abstract
- The manufacturing and finishing (honing) of cylinder liners for the automotive industry is a constant challenge in order to reduce friction losses and oil consumption. A better knowledge of surfaces generated during plateau honing is then required for optimization of the process. Despite a well-known and controlled honing process, variations in surface roughness appear due to honing tool wear and need to be mapped and analyzed. The following paper proposes to map the variations in roughness by using confocal 3D measuring equipment able to inspect any area of a cylinder liner. Six motor blocks, each with five cylinder liners, were evaluated with 20 topography measurements per liner (giving six hundred 3D measurements in total). In addition to standard 3D roughness parameters, tailor made parameters extracting honing texture information are computed. The results show that only a few parameters (Spk, Ssc and Sk) do correlate with the honing tool wear specific to each cylinder. Tailor made parameters indicate similar results. Indeed, as the honing tool wears down, the cylinder liner surface gets rougher plateau or peaks and sharper asperities indicating that ploughing occurs instead of cutting. In future, experimental models could be built in order to perform production and functional optimizations. © 2015 Elsevier Inc. All rights reserved.
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| 3. |
- Cabanettes, Frédéric, 1982-, et al.
(författare)
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Topography of as built surfaces generated in metal additive manufacturing : A multi scale analysis from form to roughness
- 2018
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Ingår i: Precision engineering. - Philadelphia, PA : Elsevier. - 0141-6359 .- 1873-2372. ; 52, s. 249-265
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Tidskriftsartikel (refereegranskat)abstract
- Topographies are one of the challenges for the development of the metal additive manufacturing promising technique. The article investigates multi scale topographies (from form to roughness) of as built surfaces generated by selective laser melting (SLM). Different building inclinations of samples were observed both for upskin and downskin surfaces with a wide range of measuring techniques. The two main aims are: (i) to make a critical review of measuring techniques at different scales, (ii) to enlighten the different surface generation phenomena (and the corresponding scale) occurring during additive manufacturing. The effect of heat treatment on each scale of the topography is also discussed. It is found that the focus variation technique is well suited for AM surfaces. Concerning the observation of the inclined surfaces, some parameters are emphasized as good indicators of typical signatures of AM surfaces: isotropy for the weld track component, the skewness and Rsm for the staircase effect, fractal dimension for the presence of partly melted particles. The different parameters studied helps to model and understand the different surface generation phenomena aforementioned. © 2018 Elsevier Inc.
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| 4. |
- Daemi, Bita, 1982-, et al.
(författare)
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Lateral performance evaluation of laser micromachining by highprecision optical metrology and image analysis
- 2017
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Ingår i: Precision engineering. - : Elsevier. - 0141-6359 .- 1873-2372.
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Tidskriftsartikel (refereegranskat)abstract
- Today several techniques are available for micro-manufacturing. Yet, it is difficult to assess the precisionand lateral X,Y accuracy of these techniques. The available accuracy information is usually based on spec-ifications given by machine suppliers. This information is based on in-house laboratory tests performedby dedicated machine operators and within an adapted environment. In practice, the accuracy is likelyto vary due to environmental conditions, materials and operator skills. In order to check the specifica-tions in realistic environments the EUMINAfab infrastructure consortium initiated a set of independenthigh precision onsite verification tests on different laser micromachining installations. In addition toproviding performance verification, it gave the participating partners real capability information of theirequipment and possibilities to improve machining performance to a higher level. In this study a compre-hensive verification test was designed and carried out by using a high precision metrology method for 2Dmeasurements based on subpixel resolution image analysis. This methodology improved our knowledgeof the capabilities of three laser micromachining installations, and showed that specifications at singlemicron levels are hard to obtain.
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| 5. |
- Ding, X., et al.
(författare)
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A study of the cutting performance of poly-crystalline oxygen free copper with single crystalline diamond micro-tools
- 2012
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Ingår i: Precision engineering. - : Elsevier BV. - 0141-6359 .- 1873-2372. ; 36:1, s. 141-152
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Tidskriftsartikel (refereegranskat)abstract
- A study was carried out to investigate the crystallographic effects on the performance of cutting poly-crystalline oxygen free copper C10200 (OFC) with single crystalline diamond (SCD) micro-tools. At both large cutting depth and cross-feed rate, as the micro-tool traversed a grain with a crystallographic orientation less favorable for a stable machining process, the work material in front of the rake face was found to be severely deformed. This may lead to a reduced shear angle, thick chip, striation at the back of the chip, high cutting forces, degraded machined surface and the possibility of burr formation. The results showed minimal variations in the machined surface integrity and cutting forces compared to cut amorphous NiP plating with micro-tools. For a high cutting depth, burrs were also observed due to material deformation and pile-up occurring at the groove edges since the localized stress probably built up in front of the rake face. Cutting strategies were demonstrated to improve the performance of cutting OFC with micro-tools and to generate high aspect ratio micro-pillar arrays.
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| 6. |
- Jansson, Anton, 1986-, et al.
(författare)
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Multi-material gap measurements using dual-energy computed tomography
- 2018
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Ingår i: Precision engineering. - : Elsevier. - 0141-6359 .- 1873-2372. ; 54, s. 420-426
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Tidskriftsartikel (refereegranskat)abstract
- X-ray computed tomography is a highly versatile investigation method with applications in a wide range ofareas. One of the areas where the technique has seen an increased usage, and an increased interest from industry,is in dimensional metrology. X-ray computed tomography enables the measurement of features and dimensionsthat are difficult to inspect using other methods. However, there are issues with the method when it comes tomeasurements of objects that consist of several materials. In particular, it is difficult to obtain accurate computedtomography results for all materials when the attenuation of materials differs significantly. The aim of this workwas to measure small air gaps between different materials using dual-energy X-ray computed tomography. Thedual-energy method employed in this work uses two energy spectra and fuses the data in the projections spaceusing non-linear fusion. The results from this study show that the dual-energy method used in this work was ableto capture more measurements than regular absorption computed tomography in the case of specimens withhighly different attenuation, enabling, in particular, the measurement of smaller gaps. The contrast-to-noise ratiowas also increased significantly with the use of dual-energy.
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| 7. |
- Song, Yimin, et al.
(författare)
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Kinematic calibration of a 5-DoF parallel kinematic machine
- 2016
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Ingår i: Precision engineering. - : Elsevier. - 0141-6359 .- 1873-2372. ; 45, s. 242-261
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Tidskriftsartikel (refereegranskat)abstract
- Kinematic calibration of a 5 degree-of-freedom parallel kinematic machine (T5 PKM) resorting to a step-by-step strategy is carried out, which conducts the identification modeling, measurement planning, parameter identification and modification of substructure I and then substructure II. On the basis of geometrical error model, a ridge estimation method based on L-curve selection is applied to the ill-conditioning inverse problem of the identification modeling of both substructures. Sensitivity analysis of substructure I and parameter analysis of substructure II are then employed to select the geometrical error parameters to be identified. Measurement planning is conducted by four principles to minimize the number of measuring configurations. Parameter identification and modification is implemented by SolidWorks simulation, which is able to check the correctness of identification modeling and measuring planning and to virtually manipulate the experimental procedure. Finally, kinematic calibration experiments are performed, which effectively validates that the proposed kinematic calibration is highly accurate and efficient.
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| 8. |
- Szipka, Karoly, et al.
(författare)
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Measurement and analysis of machine tool errors under quasi-static and loaded conditions
- 2018
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Ingår i: Precision engineering. - : Elsevier. - 0141-6359 .- 1873-2372. ; 51, s. 59-67
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Tidskriftsartikel (refereegranskat)abstract
- Machine tool testing and accuracy analysis has become increasingly important over the years as it offers machine tool manufacturers and end-users updated information on a machine’s capability. A machine tooĺs capability may be determined by mapping the distribution of deformations and their variation range, in the machine tool workspace, under the cumulative effect of thermal and mechanical loads. This paper proposes a novel procedure for the prediction of machine tool errors under quasi-static and loaded conditions. Geometric errors and spatial variation of static stiffness in the work volume of machines are captured and described through the synthesis of bottom-up and top-down model building approaches. The bottom-up approach, determining individual axis errors using direct measurements, is applied to estimate the geometric errors in unloaded condition utilizing homogeneous transformation matrix theory. The top-down approach, capturing aggregated quasi-static deviations using indirect measurements, estimates through an analytical procedure the resultant deviations under loaded conditions. The study introduces a characterization of the position and direction dependent static stiffness and presents the identification how the quasi-static behavior of the machine tool affects the part accuracy. The methodology was implemented in a case study, identifying a variation of up to 27% in the stiffness response of the machine tool. The prediction results were experimentally validated through cutting tests and the uncertainty of the measurements and the applied methodology was investigated to determine the reliability of the predicted errors.
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| 9. |
- Theissen, Nikolas Alexander, 1992-, et al.
(författare)
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Measurement for the identification of static and quasi-static rotational stiffness
- 2021
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Ingår i: Precision engineering. - : Elsevier BV. - 0141-6359 .- 1873-2372. ; 72, s. 215-223
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Tidskriftsartikel (refereegranskat)abstract
- Machine tool calibration can be employed to optimise tool path trajectories through on- and off-line compensation of anticipated deflections, which result from a process plan, and to assess the machine tools capability to comply with the geometric dimensions and tolerances of a process plan.This work presents a measurement for the identification of static and quasi-static rotational stiffness of a rotational joint of 5-axis machining centres. This work shall serve as a basis towards the calibration of translational as well as rotational stiffness of 5-axis machining centres. The novelty of this work lies partly in the measurement procedure for the quasi-static rotational stiffness, which relies on multiple circular trajectories, as well as in the comparison of the static and quasi-static rotational stiffness of machine tools, which is usually identified using finite element approaches. The measurement procedure for the static rotational stiffness consists of inducing a static load directly, from an overhead factory crane, to a single rotational joint and measuring its deflection with both three LVDTsLinear Variable Differential Transformers (LVDTs) as well as three Non-Contact Capacitive Probes (NCCPs). While the measurement for the quasi-static rotational stiffness induces quasi-static loads indirectly from the Loaded Double Ball Bar, with different magnitudes and radii from the axis of rotation, between the tool centre point and the machine tool table. The quasi-static measurement procedure measures the deflection with both three LVDTs as well as three NCCPs while the spindle tracks circular trajectories inscribed by the movement of the rotary axis. The measurement procedures are implemented in two case studies on 5-axis machining centres with significantly different kinematic configurations to be able to highlight and discuss the limitations of the applicability of the method. The presented method works well for machining centres with symmetric and acceptably with asymmetric structures due to the corresponding symmetry of the deflection field.Finally, the manuscript concludes with a contextualisation of the introduced measurement procedure towards fully calibrated machine tool models, i.e. translation and rotation as well as static and dynamic, which together with customised post-processors and process models, might form the future basis of a stiffness volumetric compensation system.
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| 10. |
- Wang, Lihui, et al.
(författare)
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A Novel Meshing Algorithm for Dynamic Finite Element Analysis
- 2003
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Ingår i: Precision engineering. - 0141-6359 .- 1873-2372. ; 27:3, s. 245-257
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes a new algorithm to handle problems in dynamic finite element analysis and run-time simulation, where mesh re-generation or dynamic adjustment is required. Based on a concept called coded box cell (CBC) substitution, this algorithm can be applied to both initial mesh generation and dynamic mesh adjustment along the border zones of multiple primitives that form an entire model. During the initial mesh generation, appropriate labels are assigned to the nodes and the faces of each finite element. These labels are used to facilitate decision-making in dynamic mesh adjustment. A mapping technique is adopted to transform curved surfaces to plain surfaces for the ease of automatic mesh adjustment while still using the same algorithm. The results of a case study show that a finite element mesh can be adjusted dynamically and locally around its border zone; and the algorithm can be utilized effectively to simulate the thermal behavior of a device under real operating conditions.
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