scholarly journals Analysis of Surface Microgeometry Created by Electric Discharge Machining

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3830
Author(s):  
Tomasz Bartkowiak ◽  
Michał Mendak ◽  
Krzysztof Mrozek ◽  
Michał Wieczorowski
Keyword(s):  
Curvature Tensor ◽  
Electric Discharge ◽  
Surface Characterization ◽  
Tensor Analysis ◽  
Principal Curvatures ◽  
Motif Analysis ◽  
Electric Discharge Machining ◽  
Surface Microgeometry ◽  
Focus Variation

The objective of this work is to study the geometric properties of surface topographies of hot-work tool steel created by electric discharge machining (EDM) using motif and multiscale analysis. The richness of these analyses is tested through calculating the strengths of the correlations between discharge energies and resulting surface characterization parameters, focusing on the most representative surface features—craters, and how they change with scale. Surfaces were created by EDM using estimated energies from 150 to 9468 µJ and measured by focus variation microscope. The measured topographies consist of overlapping microcraters, of which the geometry was characterized using three different analysis: conventional with ISO parameters, and motif and multiscale curvature tensor analysis. Motif analysis uses watershed segmentation which allows extraction and geometrically characterization of each crater. Curvature tensor analysis focuses on the characterization of principal curvatures and their function and their evolution with scale. Strong correlations (R2 > 0.9) were observed between craters height, diameter, area and curvature using linear and logarithmic regressions. Conventional areal parameter related to heights dispersion were found to correlate stronger using logarithmic regression. Geometric characterization of process-specific topographic formations is considered to be a natural and intuitive way of analyzing the complexity of studied surfaces. The presented approach allows extraction of information directly relating to the shape and size of topographic features of interest. In the tested conditions, the surface finish is mostly affected and potentially controlled by discharge energy at larger scales which is associated with sizes of fabricated craters.

Characterization of 3D Surface Texture Directionality Using Multi-Scale Curvature Tensor Analysis

2017 ◽  
Author(s):  
Tomasz Bartkowiak
Keyword(s):  
Curvature Tensor ◽  
Surface Texture ◽  
Sampling Interval ◽  
Tensor Analysis ◽  
Principal Curvatures ◽  
Multi Scale ◽  
Principal Directions ◽  
2D And 3D ◽  
3D Surface Texture

Anisotropy of surface texture can in many practical cases significantly affect the interaction between the surface and phenomena that influence or are influenced by the topography. Tribological contacts in sheet forming, wetting behavior or dental wear are good examples. This article introduces and exemplifies a method for quantification and visualization of anisotropy using the newly developed 3D multi-scale curvature tensor analysis. Examples of a milled steel surface, which exhibited an evident anisotropy, and a ruby contact probe surface, which was the example of isotropic surface, were measured by the confocal microscope. They were presented in the paper to support the proposed approach. In the method, the curvature tensor T is calculated using three proximate unit vectors normal to the surface. The multi-scale effect is achieved by changing the size of the sampling interval for the estimation of the normals. Normals are estimated from regular meshes by applying a covariance matrix method. Estimation of curvature tensor allows determination of two directions around which surface bends the most and the least (principal directions) and the bending radii (principal curvatures). The direction of the normal plane, where the curvature took its maximum, could be plotted for each analyzed region and scale. In addition, 2D and 3D distribution graphs could be provided to visualize anisotropic or isotropic characteristics. This helps to determine the dominant texture direction or directions for each scale. In contrast to commonly used surface isotropy/anisotropy determination techniques such as Fourier transform or autocorrelation, the presented method provides the analysis in 3D and for every region at each scale. Thus, different aspects of the studied surfaces could clearly be seen at different scales.

Characterization of Electric Discharge Machining for Silicon Carbide Single Crystal

2008 ◽  
Vol 600-603 ◽  
pp. 855-858 ◽  
Author(s):  
Tomohisa Kato ◽  
Toshiya Noro ◽  
Hideaki Takahashi ◽  
Satarou Yamaguchi ◽  
Kazuo Arai
Keyword(s):  
Silicon Carbide ◽  
High Temperature ◽  
Electric Discharge ◽  
High Voltage ◽  
High Speed ◽  
Surface Damage ◽  
Lower Surface ◽  
Etch Pits ◽  
Electric Discharge Machining

In this study, we report electric discharge machining (EDM) as a new cutting method for silicon carbide (SiC) single crystals. Moreover, we discuss characteristics and usefulness of the EDM for the SiC. The EDM realized not only high speed and smooth cutting but also lower surface damage. Defect propagation in the EDM SiCs have been also estimated by etch pits observation using molten KOH, however, we confirmed the EDM has caused no damage inside the SiCs in spite of high voltage and high temperature during the machining.

Characterization of Damage Induced by Electric Discharge Machining and Wiresawing with Loose Abrasive at Subsurface of SiC Crystal

2014 ◽  
Vol 778-780 ◽  
pp. 362-365
Author(s):  
Yukari Ishikawa ◽  
Yong Zhao Yao ◽  
Koji Sato ◽  
Yoshihiro Sugawara ◽  
Yoshihiro Okamoto ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electric Discharge ◽  
Stacking Faults ◽  
Scattering Method ◽  
Electric Discharge Machining ◽  
Silicon Carbon ◽  
Transmission Electron ◽  
Cut Surface

The damage induced at the cut surface of SiC crystal by slicing were investigated by Raman scattering method and transmission electron microscopy. Electric discharge machining (EDM) predominately forms cracks, silicon, carbon and 3C-SiC by 6H-SiC pyrolysis and wiresawing with loose abrasive (WSLA) induces triangular crystal disordered area, stacking faults and dislocation loop bundles by stressing at the cut surfaces of SiC crystal.

A Characterization of Process–Surface Texture Interactions in Micro-Electrical Discharge Machining Using Multiscale Curvature Tensor Analysis

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Tomasz Bartkowiak ◽  
Christopher A. Brown
Keyword(s):  
Curvature Tensor ◽  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
Sampling Interval ◽  
Tensor Analysis ◽  
Strong Correlations ◽  
Micro Electrical Discharge Machining ◽  
Surface Topographies ◽  
Unit Vectors

The objectives of this work are to demonstrate the use of multiscale curvature tensor analysis for characterizing surfaces of stainless steel created by micro-electrical discharge machining (μEDM), and to study the strengths of the correlations between discharge energies and resulting surface curvatures (i.e., principal, Gaussian, or mean curvatures) and how they change with scale. Surfaces were created by μEDM techniques using energies from 18 nJ to 16,500 nJ and measured by confocal microscope. The curvature tensor T is calculated using three proximate unit vectors normal to the surface. The multiscale effect is achieved by changing the size of the sampling interval for the estimation of the normals. Normals are estimated from regular meshes by applying a covariance matrix method. Strong correlations (R2 > 0.9) are observed between calculated principal maximal and minimal as well as mean and Gaussian curvatures and discharge energies. This method allows detailed analysis of the nature of surface topographies and suggests that different formation processes governed the creation of surfaces created by higher energies.

scholarly journals Focus variation technology as a tool for tissue surface characterization

Cellulose ◽  
2021 ◽  
Author(s):  
Jürgen Reitbauer ◽  
Franz Harrer ◽  
Rene Eckhart ◽  
Wolfgang Bauer
Keyword(s):  
Surface Characterization ◽  
Final Analysis ◽  
Surface Characteristics ◽  
Interfacial Area ◽  
Wide Field ◽  
Tissue Paper ◽  
Spatial Frequencies ◽  
Tissue Surface ◽  
Focus Variation

Abstract The surface of tissue paper is relatively complex compared to other paper grades and consists of several overlapping structures like protruding fibres, crepe and fabric-based patterns at different spatial frequencies. The knowledge of tissue surface characteristics is crucial when it comes to improvement with respect to surface softness and the perceptual handfeel of tissue products. In this work we used the optical based, non-contact measurement principle of focus variation for surface characterization of dry-creped, textured and through air dried (TAD) tissue. Based on the three tissue grades, a procedure which includes the characterization of the whole tissue surface throughout different scales within one setup, was developed. Surprisingly, focus variation was rarely used in tissue-related research, as it provides robust and reliable 3D surface information which can be used for further areal surface analysis. Special attention was given to the preparation and discussion of the raw data up to the final analysis including several spatial filtering steps. Enhanced surface parameters like the developed interfacial area ratio (Sdr) and the power spectral density (PSD) were used to describe the surface adequately. The surface roughness of the three tissue grades was compared, with the textured tissue showing the highest roughness in Sdr and PSD analysis. Although both methods are based on different principles, a high correlation in terms of evaluated roughness is evident. Regular structures like crepe and patterns are obtainable as peaks at the respective frequency with a certain intensity in the PSD evaluation. Apart from topography in terms of structures and roughness, the wide field of view of the focus variation measurement also allows assessment of effects related to flocculation and sheet formation. The developed procedure could also be appropriate for other fibre based materials and/or fabrics, which are similar to tissue with respect to optical properties such as for example nonwovens. Graphic abstract

Research on Statistical Parameters of 3-D Roughness for Micro Wire Electric Discharge Machining Surface

2013 ◽  
Vol 572 ◽  
pp. 287-290
Author(s):  
Li Bin Guo ◽  
Hai Cui ◽  
Bin Zhang ◽  
Zhi Hang Zhang
Keyword(s):  
Electric Discharge ◽  
Surface Characterization ◽  
Three Dimensional ◽  
Statistical Characteristics ◽  
Height Distribution ◽  
Statistical Parameters ◽  
Electric Discharge Machining ◽  
Functional Parameters ◽  
Wire Electric Discharge Machining ◽  
Functional Areas

Amplitude parameters and functional parameters of three-dimensionalroughness are established by statistics geometry. Since micro wire electric discharge machining (MWEDM) surface approximately follows the Gauss distribution, its statistical characteristics are different from cutting processing surface. Characterization meaning between MWEDM surface and cutting processing surface is rather different. This study begins with shape parameters’ mathematics essence of surface height distribution of three-dimensionalroughness, analyzes their definite characterization meanings for MWEDM surface, deeply researches bearing ratio curve of MWEDM surface, reasonably ascertains its functional areas and finally establishes nine functional parameters where volume parameter is the main one.

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