White Layer and Surface Roughness in High Speed Milling of P20 Steel

Abstract

Using solid carbide straight end mills with TiAlN coating, A P20 steel at 41HRC is machined in the cutting speed range of 301 to 754m/min. The workpiece subsurface are examined using scanning electron microscope (SEM) and surface roughness tester. The results show that the white layer is produced in all of the cutting conditions tested, and the white layer thickness and surface roughness are dependent on the cutting conditions. The result obtained by analysis of variance analysis shows that feed rate and cutting speed are the most significant effects on the white layer thickness and surface roughness. Furthermore, the mathematical models for the white layer thickness and the surface roughness in high speed side milling of hardened P20 steel are proposed, respectively.

Microstructural Alteration and Microhardness at Near-Surface of Aisi H13 Steel by Hard Milling

“…Elbestawi et al (1997) found the white layers formation in HSM of hardened AISI H13 using PCBN ball-nose end mills, which was dependant on edge preparation and tool wear. Pang et al (2007) pointed out that the white layer is produced in all of the cutting conditions tested and the white layer thickness and surface roughness are dependent on the cutting speed and feed rate during high-speed machining P20 steel at 41 HRC with TiAlN coated solid carbide straight end mills.…”

“…The thin hard layer is benefit to improving wear resistance of contact surfaces; however, the white layer is brittle and often possesses a tensile compressive stress and causes crack permeation, which seem to be detrimental to the machined component's performance, such as fatigue life, stress corrosion and wear resistance (Aramcharoen and Mativenga, 2008;Pang et al, 2007), and therefore need a post-finishing process. The above-mentioned effects are a direct consequence of the mechanical and physical characteristics of the white layer.…”

Genetic Evolutionary Approach for Cutting Forces Prediction in Hard Milling

“…With the advances in cutting tool technologies, hard milling has been recently employed to machine hardened steels (> 30 HRC) in making dies and molds for various automotive and electronic components as well as plastic molding parts [2]. Previous research in hard milling has focused on tool life [3], surface smoothness [4], white layer effect [5], cutting force modelling [6], machine stability [6], and optimum cutting parameters [7]. In milling, cutting forces are one of the basic parameters for selecting cutting parameters, and in many cases the most important [8].…”