Mini symposium on cutting and machining: 25 years of ESAFORM activity

This paper reports on the state of the art in the experimental and numerical investigations of cutting and machining processes. The contributions on the above-mentioned processes and published on the Proceedings of the European Scientific Association for material FORMing (ESAFORM) Conferences are highlighted. In particular, this literature review is an update of a previous one conducted in 2007, after ten years of the ESAFORM activities, and it confirms the crucial role played by the minisymposium on Machining and Cutting in this field. In fact, the research has been quite active even in these last fifteen years, as demonstrated by the number of contributions and their relevant scientific contents. As overall, this review shows as the minisymposium on Machining and Cutting, that has been organized since 2001 with no interruptions, has contributed to the scientific progress on the study of the material removal processes

Tool wear and cutting forces under cryogenic machining of titanium alloy (Ti17)

Titanium alloy is well known for its difficulty to machine, owing to the important “tool wear” phenomenon. Machining assistance is an interesting solution to lengthen the tool lifetime. In this study, we focused on the effect of cryogenic assistance—during machining of Ti17—on the tool wear and cutting forces for different combinations of cutting speed, feed rate and depth of cut. Compared to conventional lubrication, cryogenic support lengthens the tool life for all tested conditions and has no significant influence on cutting force. A comparison of the cryogenic effect and high-pressure water jet assistance is also presented

Effect of supply conditions of liquid nitrogen on the cryogenic assisted machining of the Ti64 Titanium alloy

This study focuses on the optimization of the machining assisted by cryogenic cooling. The main objective is to analyze the effect of the pressure and the flow of liquid nitrogen on tool life when machining titanium alloy Ti-6Al-4V using the cryogenic assisted machining. A nozzle holder has been specially developed for this study to ensure positioning and the replacement of calibrated nozzles of different diameters. Several nozzle diameters have been therefore used in order to vary the pressure and the flow according to tests to be conducted. The flow rate has been varied between 1.2 l/min and 3.4 l/min for two pressure ranges 8-10 bar and 4-5 bar respectively.The machining tests have allowed to highlight the effect of the pressure and flow rate of liquid nitrogen jet on the tool life. Indeed, the results showed that increasing the flow rate increases the tool life. In addition, the increase in pressureslowed down the evolution of the wear and further improves the tool life.Indeed, in all tested cases, the cryogenic assistance improves the tool life but the best results have been obtained for the highest pressure and flow rate. Moreover, surface integrity has been greatly improve

Numerical investigation and modeling of residual stress field variability impacting the machining deformations of forged part

International audienceAluminum alloys are widely used for structural parts in the aerospace industry. Those parts are usually machined from rolled plates or forged blanks, and heat treatments are carried out to reach the necessary mechanical properties. Forming and heat treatments induce residual stresses that generate deformations during and after machining because material removal modifies their balance. One major issue in industry is the important variability of the residual stress field in forged blanks. A better knowledge of the residual stress field will enable the definition of better machining strategy to minimize the deformations. In order to understand and manage this variability, a sensibility analysis was performed to investigate the impact of their different potential sources. It relies on a coupling of 2D-FEM and beam model simulations. Then, this work introduces a model reduction technique (by POD and SVD) to build a model of the variability of a stress field and shows how it could be used on the production line

Influence of the microstructure of a Ti5553 titanium alloy on chip morphology and cutting forces during orthogonal cutting

Titanium alloys, largely used for aeronautical applications, are difficult to machine. High cutting forces, chip serration and important tool wear reflect this poor machinability, limiting productivity. One way of improving the machinability of titanium alloys consists of controlling their microstructure. In the present work, the impact of the microstructure of the Ti5553 alloy on chip formation and cutting forces is investigated. For this purpose, a novel experimental approach is proposed. Orthogonal cutting tests are performed on eight different microstructures, which allows studying the impact of the α-phase fraction as well as the size and shape of α particles. Also, an original post processing method based on machine learning provides chip morphological information from images recorded with two high speed cameras. Such information is completed with the cutting forces measured with a dynamometer. In contrast with commonly used approaches, the proposed method is not limited to the formation of a few segments, but uses the full dataset acquired during a test. The results obtained for the different microstructures indicate that no direct link can be established between the cutting forces and their hardness as minimal cutting forces are obtained for microstructures with an intermediate hardness. For microstructures providing low hardness, high cutting forces result from a significantly thick chip. In opposition, for the microstructures leading to high hardness, an important flow stress generates high cutting forces. This study also suggests that chip morphology is primarily affected by the α-phase fraction while the size and morphology of α-phase particles have little influence