Cryogenic Milling: Study of the Effect of CO2 Cooling on Tool Wear When Machining Inconel 718, Grade EA1N Steel and Gamma TiAl

David Fernández,Ion Bengoetxea,Alejandro Sandá

doi:10.3390/lubricants7010010

Abstract

The need for machining advanced materials has increased exponentially in recent years. Ni-based alloys, Ti-based alloys or some steel grades are commonly used in transport, energy generation or biomedicine industries due to their excellent properties that combine hardness, high temperature strength and corrosion resistance. These desirable properties make such alloys extremely difficult to machine, inducing a quick cutting tool wear that must be overcome. In the last decade, cryogenic machining has emerged in order to improve the machining of these materials. By means of cryogenic fluids such as cutting coolants, significant improvements in the life of cutting tools are obtained. However, most studies on this new technology are focused on turning processes, because of the difficulty of introducing cryogenic fluids through a rotary tool in processes such as drilling and milling. In this study, a cryogenic milling system integrated within the tool holder is used for milling Gamma TiAl, Inconel 718 and grade EA1N steel using carbon dioxide as a coolant. This system has been compared with the traditional cooling method (emulsion) in terms of tool life to check if it is possible to improve the machining operation in terms of efficiency by supplying the cryogenic coolant directly to the cutting zone. The results show that by replacing traditional pollutant cooling fluids with other more ecologically-friendly alternatives, it is possible to improve tool life by 100% and 175% in the cases of Gamma TiAl and grade EA1N steel, respectively, when using the new delivery system for the coolant.

Highlights

The growth of industry in developed countries comes with scientific and technological challenges in order to advance in sectors such as the aeronautical industry, biomedical components and the extraction of gas and petroleum
The aim of this paper is to present a new design for cryogenic milling that presents the particularity of driving the CO2 “through the tool holder”
This paper describes the experimental tests made in these materials that have not been tested to date by an internal cryogenic machining device, to determine the efficiency of each tested cooling method in terms of cutting tool wear

Summary

Introduction

The growth of industry in developed countries comes with scientific and technological challenges in order to advance in sectors such as the aeronautical industry, biomedical components and the extraction of gas and petroleum. Industries of this kind have, as a common denominator, the use of advanced materials with excellent mechanical properties. Grade EA1N steel is another example; it is an alloy often used in the railway industry which has special properties to meet the demands of train axles These functional benefits entail a difficult challenge in terms of machinability. The high resistance of these materials, even at high temperatures, increases the mechanical load in the machining process and their low thermal conductivity produces heat accumulation in the cutting zone

Objectives

Results

Conclusion