Progressive Tool Wear in Cryogenic Machining: The Effect of Liquid Nitrogen and Carbon Dioxide

Yusuf Kaynak,Armin Gharibi

doi:10.3390/jmmp2020031

Yusuf Kaynak, Armin Gharibi

Open Access

https://doi.org/10.3390/jmmp2020031

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Abstract

This experimental study focuses on various cooling strategies and lubrication-assisted cooling strategies to improve machining performance in the turning process of AISI 4140 steel. Liquid nitrogen (LN2) and carbon dioxide (CO2) were used as cryogenic coolants, and their performances were compared with respect to progression of tool wear. Minimum quantity lubrication (MQL) was also used with carbon dioxide. Progression of wear, including flank and nose, are the main outputs examined during experimental study. This study illustrates that carbon dioxide-assisted cryogenic machining alone and with minimum quantity lubrication does not contribute to decreasing the progression of wear within selected cutting conditions. This study also showed that carbon dioxide-assisted cryogenic machining helps to increase chip breakability. Liquid nitrogen-assisted cryogenic machining results in a reduction of tool wear, including flank and nose wear, in the machining process of AISI 4140 steel material. It was also observed that in the machining process of this material at a cutting speed of 80 m/min, built-up edges occurred in both cryogenic cooling conditions. Additionally, chip flow damage occurs in particularly dry machining.

Highlights

In hard turning, high hardness of workpieces, large cutting forces, and high temperatures at the tool–workpiece interface impose extreme requirements for tool rigidity and tool wear resistance [1,2]
It is possible to reduce the cost of the cutting tools used in the process by using a carbide cutting tool when machining hardened steel
High temperature in the machining process of such steel limits the usage of carbide cutting tools if effective cooling and/or lubrication are not implemented [1]

Summary

Introduction

High hardness of workpieces, large cutting forces, and high temperatures at the tool–workpiece interface impose extreme requirements for tool rigidity and tool wear resistance [1,2]. High temperature in the machining process of such steel limits the usage of carbide cutting tools if effective cooling and/or lubrication are not implemented [1]. As LN2 can be stored in an insulated tank at very low temperature [11], it can be used for cooling during the machining processes. This might negatively influence the machine and equipment [12]. An effective coolant is achieved at −78.5 ◦C because of phase transformation and the Joule-Thomson effect [11,13]

Objectives

Methods