Estimation of Fatigue Life of Cold Work Tool Steel Machined by Electrical Discharge Turning

Year 2021, Volume: 24 Issue: 2, 495 - 502, 01.06.2021

Ramazan Cakıroglu , Mustafa Günay

https://doi.org/10.2339/politeknik.705903

Cited By: 3

Abstract

In this study, it was aimed to determine the effects of machining parameters on the surface integrity and fatigue life of the machined part in electrical discharge turning (EDT). Initially, a mechanism was designed and manufactured to ensure rotation of the workpiece. EDT experiments were carried out on AISI L2 tool steel using three different discharge currents, pulse on time, pulse off time and constant rotational speed. The experiments were carried out according to the L9 orthogonal array, and Rz, Sm and hardness values were measured as processing performance outputs. Finally, the fatigue life of the machined parts was estimated by applying the √area model and the change of theoretical fatigue life according to the machining parameters was investigated. According to experimental results, an increase in Rz and Sm parameters was determined with increasing the discharge current and pulse on time. The lowest Rz and Sm values were obtained at 3 A discharge current, 3 µs pulse on time and 5 µs pulse off time. Based on Taguchi analysis, the optimum theoretical fatigue stress was calculated as 643.932 MPa with √area model for the machined workpiece in the A1Ton1Toff3 experiment sequence.

Keywords

Electro erosion, turning, surface roughness, fatigue life, tool steel

Elektro Erozyonla Tornalama Yöntemiyle İşlenen Soğuk İş Takım Çeliğinin Yorulma Ömrünün Tahmini

Abstract

Bu çalışmada, elektro erozyon ile tornalamada (EET) işleme parametrelerinin yüzey bütünlüğü ve işlenmiş parçanın yorulma ömrüne etkilerinin belirlenmesi amaçlanmıştır. İlk olarak, iş parçasının dönmesini sağlamak amacıyla bir mekanizma tasarlanarak imal edilmiştir. EET deneyleri, AISI L2 takım çeliği üzerinde üçer farklı boşalım akımı, vurum süresi ve bekleme süresi ile sabit devir sayısı kullanılarak yapılmıştır. Deneyler, L9 dikey dizisine göre yapılmış olup, işleme performans çıktıları olarak Rz, Sm ve sertlik değerleri ölçülmüştür. Son olarak, √area modeli uygulanarak işlenen parçaların yorulma ömrü tahmin edilmiş ve işleme parametrelerine göre teorik yorulma ömrünün değişimi araştırılmıştır. Deneysel sonuçlara göre, boşalım akımı ve vurum süresinin artmasıyla Rz ve Sm parametrelerinde bir artış belirlenmiştir. En düşük Rz ve Sm değerleri 3 A boşalım akımı, 3µs vurum süresi ve 5 µs bekleme süresinde elde edilmiştir. Taguchi analizine göre optimum teorik yorulma gerilmesi A1Ton1Toff3 deney dizisinde işlenen parça için √area modeli ile 643.932 MPa olarak hesaplanmıştır.

Keywords

Elektro erozyon, Tornalama, Yüzey pürüzlülüğü, Yorulma ömrü, Takım çeliği

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