Study on the white layer in wire electrical discharge trim cutting of bearing steel GCr15

2019 ◽  
Vol 102 (5-8) ◽  
pp. 2375-2386 ◽  
Author(s):  
Zhi Chen
Keyword(s):  
Electrical Discharge ◽  
White Layer ◽  
Bearing Steel ◽  
Trim Cutting

scholarly journals Experimental Study on the Influence of Machining Conditions on the Quality of Electrical Discharge Machined Surfaces of aluminum alloy Al5052

Machines ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 12 ◽  
Author(s):  
Angelos P. Markopoulos ◽  
Emmanouil-Lazaros Papazoglou ◽  
Panagiotis Karmiris-Obratański
Keyword(s):  
Aluminum Alloy ◽  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
Removal Rate ◽  
White Layer ◽  
Machining Parameters ◽  
Machining Processes ◽  
Machining Conditions ◽  
Pulse On Time ◽  
Machined Surfaces

Although electrical discharge machining (EDM) is one of the first established non-conventional machining processes, it still finds many applications in the modern industry, due to its capability of machining any electrical conductive material in complex geometries with high dimensional accuracy. The current study presents an experimental investigation of ED machining aluminum alloy Al5052. A full-scale experimental work was carried out, with the pulse current and pulse-on time being the varying machining parameters. The polishing and etching of the perpendicular plane of the machined surfaces was followed by observations and measurements in optical microscope. The material removal rate (MRR), the surface roughness (SR), the average white layer thickness (AWLT), and the heat affected zone (HAZ) micro-hardness were calculated. Through znalysis of variance (ANOVA), conclusions were drawn about the influence of machining conditions on the EDM performances. Finally, semi empirical correlations of MRR and AWLT with the machining parameters were calculated and proposed.

EDM DISPERSION - ADVANCED TECHNOLOGY

2015 ◽  
Vol 2 (1) ◽  
pp. 314-317 ◽  
Author(s):  
Хардиков ◽  
S. Khardikov ◽  
Агеев ◽  
YEvgyeniy Agyeyev ◽  
Пикалов ◽  
...  
Keyword(s):  
Electrical Discharge ◽  
Bearing Steel ◽  
Advanced Technology ◽  
Research Results

The article presents the research results of the powder-bearing steel produced by the method of electrical discharge dispersion culled a bearing nicks

Study on the White Layer of Hard Turned GCr15 Bearing Steel

2009 ◽  
Vol 69-70 ◽  
pp. 20-23 ◽  
Author(s):  
Dong Hui Wen ◽  
Xian Li Liu ◽  
Tao Hong
Keyword(s):  
Transition Layer ◽  
Flank Wear ◽  
Bulk Material ◽  
White Layer ◽  
Bearing Steel ◽  
Formation Mechanisms ◽  
Tempered Martensite ◽  
Hard Part ◽  
Gcr15 Bearing Steel ◽  
Finishing Process

The formation mechanisms and properties of white layers produced in precision hard part machining of GCr15 hardened steels are not clearly understood to date. Microstructure of white layers formed during machining of GCr15 hardened steel (62±2 HRC) was investigated. Hard turned surface with white layer usually consists of three layers: a white layer (untempered martensite), a transition layer (over-tempered martensite), and the bulk material. Martensite, austenite and carbide are observed in the white layer, hardness of white layer is larger than that of bulk material and transition layer, it was caused by extremely small grain size and high dislocation density. The depth of white layer is about 7-14µm with the flank wear reached 0.1mm, the optimal width of the flank wear which generated low depth of white layer is essential to perform the super-finishing process.

A Comparative Study on the Effect of Surface Topography by Hard Turning vs. Grinding on Frictional Performance at Dry and Lubricated Sliding Contact

2008 ◽  
Author(s):  
R. A. Waikar ◽  
Y. B. Guo
Keyword(s):  
Surface Topography ◽  
White Layer ◽  
Frictional Coefficient ◽  
Solid Lubricants ◽  
Bearing Steel ◽  
Tribological Performance ◽  
Sliding Contact ◽  
Frictional Performance ◽  
Dry Conditions ◽  
Frictional Coefficients

Machining-induced surface topography has a significant effect on tribological performance of machined components in sliding contact. However, the effect of different surface topography by turning versus grinding on tribological performance has received very little attention. In this study four types of surface topography by turning and grinding AISI 52100 bearing steel (62 HRc) were prepared and characterized to study its effect on friction and wear in sliding contact. Dry and lubricated reciprocating sliding wear tests with an on-line acoustic emission (AE) sensor were carried out using a ball-on-disk tribometer. The experimental results have shown that: (i) the turned surfaces, regardless of the presence of a white layer, yield smaller friction of coefficients in sliding along feed marks than across sliding at both dry and lubricated conditions. However, the opposite hold true for the ground surfaces; (ii) friction of coefficients (0.6∼0.8) at dry conditions is higher for both turned and ground fresh surfaces than their white layer counterparts regardless of sliding direction. At lubricated conditions, Friction of coefficients (0.1∼0.12) are smaller for the both turned and ground fresh surfaces than the white layer surfaces in along sliding, while it is equivalent in across sliding; (iii) the trends of acoustic amplitude amplitude are consistent with those of frictional coefficients for the turned or ground surfaces at dry conditions. Similar trends are also true for the turned surfaces at lubricated conditions, but not for the ground surfaces; and (iv) the wear debris on the track may act as solid lubricants to reduce the sliding frictional coefficient. Machining induced white layers leads to a better wear resistance than the fresh surfaces in either along or across sliding.

scholarly journals Optimasi Multirespon Proses Wire Electrical Discharge Machining untuk Pengerjaan Komponen Punch and Dies Bracket Konstruksi Kapal Alumunium

2019 ◽  
Vol 12 (2) ◽  
pp. 107
Author(s):  
Fipka Bisono ◽  
Dhika Aditya P.
Keyword(s):  
Surface Roughness ◽  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
White Layer ◽  
Performance Characteristics ◽  
Machining Process ◽  
Wire Electrical Discharge Machining ◽  
Process Variables ◽  
Relational Analysis ◽  
Wedm Process

Wire electrical discharge machining(WEDM) banyak digunakan untuk proses pembuatan punch and dies. Dimana material yang digunakan memiliki tingkat kekerasan yang sangat tinggi. Parameter pemesinan yang kurang tepat dapat menyebabkan hasil pemotongan yang tidak optimal. Penelitian ini dilakukan untuk mengoptimalkan beberapa karakteristik hasil proses pemesinan secara serentak dengan cara mevariasikan variabel-variabel proses pemesinan WEDM. Karakteristik hasil proses yang diteliti antara lain adalah lebar pemotongan, kekasaran permukaan, dan tebal lapisan white layer. Proses pemesinan dilakukan pada material tool steel SKD 11. Arc on time, on time, open voltage dan servo voltage merupakan variabel-variabel proses yang akan divariasikan. Rancangan percobaan dilakukan menggunakan metode Taguchi dengan matriks ortogonal L18(21x33) dengan dua kali replikasi. Sedangkan langkah yang digunakan untuk mengoptimasi karakteristik hasil proses pemesinan yang diteliti secara serentak adalah menggunakan metode grey relational analysis (GRA). Lebar pemotongan, kekasaran permukaan dan tebal lapisan white layer memiliki performance characteristics “smaller-is-better.” Hasil dari penelitian menunjukkan nilai variabel-variabel proses pemesinan yang menghasilkan kualitas karakteristik yang paling optimum adalah sebagai berikut: arc on time (1A), on time (4?s), open voltage (70V), dan servo voltage (40V). Dengan persentase kontribusi variabel proses dari yang terbesar berturut-turut adalah on time (65,09%), open voltage (11,35%), arc on time (7,71%), dan servo voltage (5,61%). Wire electrical discharge machining (WEDM) process is commonly used to make punch and dies. WEDM services are typically used to cut hard metals. Inappropriate machining parameters can cause suboptimal cutting results. This research was conducted to optimize several characteristics of the machining process simultaneously by varying WEDM machining process variables. Performance characteristics of the WEDM process include the kerf, surface roughness and thickness of the white layer. The machining process is carried out on SKD 11 tool steel material.  Arc on time, on time, open voltage and servo voltage are process variables that will be varied. The experimental matrix design was carried out using the Taguchi method L18 (21x33) orthogonal array with two replications. Then to optimize the performance characteristics of the machining process simultaneously is using the Gray Relational Analysis (GRA) method. Performance characteristics of kerf, surface roughness, and thickness of the white layer is "smaller-is-better". The results of the experiment indicate the value of the machining process variables that produce the most optimum quality performance characteristics are as follows: arc on time (1A), on time (4?s), open voltage (70V), and servo voltage (40V). And the percentage of contribution of the process variables from the largest to smallest are as follows: on time (65,09%), open voltage (11,35%), arc on time (7,71%), and servo voltage (5,61%).

Evolution of White Layer and Residual Stress in Electrical Discharge Machining

2021 ◽  
Author(s):  
Guisen Wang ◽  
Fuzhu Han ◽  
Liang Zhu
Keyword(s):  
Residual Stress ◽  
Surface Roughness ◽  
Fatigue Life ◽  
Layer Thickness ◽  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
White Layer ◽  
Machining Parameters ◽  
Discharge Energy ◽  
White Layer Thickness

Abstract White layer and residual stress are the main reasons for the decrease in fatigue life of electrical discharge machined samples. Therefore, it is important to research the evolution of the white layer and residual stress in electrical discharge machining and explain the influence mechanism of machining parameters on them. In this study, the surface topography, white layer thickness, and residual stress of electrical discharge machined samples under different processing parameters were evaluated. The results indicated that surface roughness, white layer thickness, and residual stress increased as the discharge current (I) and pulse-on time (ton) increased. However, when the ton was short, the effect of I (≤ 9.8 A) on surface roughness is not very obvious. When the discharge energy is similar, surface roughness is high under high I conditions. When the discharge energy is similar and low, the average thickness of the white layer is thin under the low I. The effect of I on surface residual stress was greater than that of the ton. The I and ton affect the white layer and residual stress by affecting the amount of melting and removal of the materials. These results were demonstrated that the input process of discharge energy has an important influence on residual stress and the white layer. Therefore, under the premise of ensuring the processing requirements, they can be controlled by selecting the appropriate combination of the ton and I to improve the fatigue life of the workpiece.

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