Analysis of Surface Microgeometry Created by Electric Discharge Machining

Abstract

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.

Improving Machining Performance for Deep Hole Drilling in the Electrical Discharge Machining Process Using a Step Cylindrical Electrode

“…The material removal rate is an important consideration; altering the machining gap can increase the material removal rate, as well as improve surface finish [24]. The EDM process has been widely used for manufacturing molds and dies, as well as in the aerospace and automotive industries [25][26][27][28][29][30]. However, problems with deep hole machining or deep hole drilling often lead to undesirable surface quality and geometry problems.…”

Multiscale Analysis of Surface Texture Quality of Models Manufactured by Laser Powder-Bed Fusion Technology and Machining from 316L Steel

“…Since the constituents of curvature tensor could be determined at each location, statistical measures were introduced to quantify their distributions as a function of scale. Average and standard deviation measures were considered as defined in [ 34 , 35 ]. A list of the parameters with their short description is presented in Table 3 .…”

Application of Selective Induction Heating for Improvement of Mechanical Properties of Elastic Hinges

“…The popularity of polymers is associated with relatively low prices, a very good price-quality ratio and general availability [ 3 ]. Requirements for their operating, strength and aesthetic properties are growing very dynamically [ 4 , 5 ], motivating more and more scientists and companies to search for new manufacturing technologies or their improvements [ 6 , 7 , 8 ]. Nowadays, despite many years of usage, still the most developing technology is injection molding [ 9 ].…”