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A. Garay

Bio: A. Garay is an academic researcher from University of Mondragón. The author has contributed to research in topics: Machining & Machinability. The author has an hindex of 15, co-authored 30 publications receiving 1078 citations.

Papers
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Journal ArticleDOI
TL;DR: In this paper, the machinability of near-beta titanium alloys like Ti555.3 compared with the commonly used Ti6Al4V was analyzed and a correlation between the mechanical properties of work material, tool wear, and component forces was found.

473 citations

Journal ArticleDOI
TL;DR: In this article, single point turning tests of cylindrical bars were undertaken to analyse and compare the machinability of Ti6Al4V, the most common titanium alloy, and TIMETAL® 54M, a newly developed alloy with similar mechanical properties as Ti6al4V but with better machinsability.

113 citations

Journal ArticleDOI
TL;DR: In this paper, the suitability of replacing conventional cutting fluids by liquid nitrogen cooling + MQL for finishing operations in industry was discussed, and the results show that conventional cooling is the best option from both the machinability and the surface integrity point of view.

87 citations

Journal ArticleDOI
TL;DR: In this paper, a coupled empirical model is proposed to describe the particular behaviour of nickel based alloys at elevated temperatures and high strain rates, for machining FEM simulations with Inconel 718 superalloy.
Abstract: Nickel based alloys are extensively used in the aerospace industry due to the excellent corrosion resistance and high mechanical properties that are maintained up to elevated temperatures (600–800 °C). However, these superalloys are classified as difficult-to-cut and therefore modelling and simulation of the machining processes has become a key in the machinability assessment of nickel based alloys. The reliability of Finite Element Models (FEM) largely depends on the quality of input parameters, one of the most relevant being the constitutive material model representing work material behavior under high strain, strain rate and temperatures. In order to develop a reliable material model, the present work deals with a complete characterization of Inconel 718. Uniaxial compression tests at testing temperatures close to those found in machining (21–1050 °C) and high strain rates (10°−10 2 s −1 ) were performed on the Gleeble 3500 testing machine. Moreover, the microstructural analysis and microhardness measurements of the testing samples were performed, in order to correlate the microstructural state with the mechanical properties of the Inconel 718. Based on this experimental work, a new coupled empirical model is proposed to describe the particular behaviour of nickel based alloys at elevated temperatures and high strain rates. This material behaviour model introduces softening phenomena as well as the coupling between the temperature and the strain rate known to occur experimentally, for machining FEM simulations with Inconel 718 superalloy.

83 citations

Journal ArticleDOI
TL;DR: In this paper, the authors analyzed the machinability of three titanium alloys: Ti6Al4V, Ti-5Al-4V-0.6Mo 0.4Fe (TIMETAL® 54M), and Ti6246.
Abstract: Orthogonal cutting force measurements and single-point tool life tests were conducted in order to analyze the sensitivity to heat treatment on the machinability of three titanium alloys: Ti6Al4V, Ti-5Al-4V-0.6Mo-0.4Fe (TIMETAL® 54M), and Ti6246. The Ti6246 alloy showed the highest tool wear rates and the higher cutting forces in all the heat treatment conditions which could be related to its higher mechanical properties. TIMETAL® 54M alloy, a newly developed alloy with similar mechanical properties to the more commonly used Ti6Al4V, showed the lowest wear rates. Microstructural changes due to heat treatment have some influence in the machinability of the alloys. The β annealed samples of the Ti6Al4V and TIMETAL® 54M alloys, with a very coarse lamellar microstructure, showed considerably shorter tool life and higher cutting forces. The rest of the heat treatments showed no significant influence in the machining behavior of the analyzed alloys as they do not cause important microstructural changes.

56 citations


Cited by
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Journal ArticleDOI
TL;DR: In this paper, the authors focus on the following topics: (1) materials requirements in design of aircraft structures and engines, (2) recent advances in the development of aerospace materials, (3) challenges faced by recent aerospace materials and (4) future trends in aerospace materials.

477 citations

Journal ArticleDOI
TL;DR: In this article, the effect of material constitutive models and elastic-viscoplastic finite element formulation on serrated chip formation for modeling of machining Ti-6Al-4V titanium alloy is investigated.
Abstract: Titanium alloys present superior properties such as high strength-to-weight ratio and resistance to corrosion but, possess poor machinability. In this study, influence of material constitutive models and elastic–viscoplastic finite element formulation on serrated chip formation for modeling of machining Ti–6Al–4V titanium alloy is investigated. Temperature-dependent flow softening based modified material models are proposed where flow softening phenomenon, strain hardening and thermal softening effects and their interactions are coupled. Orthogonal cutting experiments have been conducted with uncoated carbide (WC/Co) and TiAlN coated carbide cutting tools. Temperature-dependent flow softening parameters are validated on a set of experimental data by using measured cutting forces and chip morphology. Finite Element simulations are validated with experimental results at two different rake angles, three different undeformed chip thickness values and two different cutting speeds. The results reveal that material flow stress and finite element formulation greatly affects not only chip formation mechanism but also forces and temperatures predicted. Chip formation process for adiabatic shearing in machining Ti–6Al–4V alloy is successfully simulated using finite element models without implementing damage models.

409 citations

Journal ArticleDOI
TL;DR: In this article, the state-of-the-art on various surface integrity characteristics during machining of nickel-based super alloys are presented, including surface roughness, defects (surface cavities, metal debris, plucking, smeared material, redeposited material, cracked carbide particles, feed marks, grooves and laps).
Abstract: Nickel-based super alloys are gaining more significance, now-a-days, with extensive applications in aerospace, marine, nuclear reactor and chemical industries. Several characteristics including superior mechanical and chemical properties at elevated temperature, high toughness and ductility, high melting point, excellent resistance to corrosion, thermal shocks, thermal fatigue and erosion are primarily responsible for wide domain of application. Nevertheless, machined surface integrity of nickel-based super alloys is a critical aspect which influences functional performance including fatigue life of the component. This review paper presents state-of-the-art on various surface integrity characteristics during machining of nickel-based super alloys. Influence of various cutting parameters, cutting environment, coating, wear and edge geometry of cutting tools on different features of surface integrity has been critically explained. These characteristics encompass surface roughness, defects (surface cavities, metal debris, plucking, smeared material, redeposited material, cracked carbide particles, feed marks, grooves and laps), metallurgical aspects in the form of surface and sub-surface microstructure phase transformation, dynamic recrystallisation and grain refinement and mechanical characteristics such as work hardening and residual stress. Microstructural modification of deformed layer, profile of residual stresses and their influence on fatigue durability have been given significant emphasis. Future research endeavour might focus on development of new grades, advanced processing techniques of the same to ensure their superior stability of microstructure and thermo-mechanical properties along with advanced manufacturing processes like additive manufacturing to achieve highest level of fatigue durability of safety critical components while maintaining acceptable surface integrity and productivity.

403 citations

Journal ArticleDOI
TL;DR: An overview of the recent advances in high performance cutting of aerospace alloys and composite currently used in aeroengine and aerostructure applications is presented in this paper, focusing on the role of hybrid machining processes and cooling strategies (MQL, high pressure coolant, cryogenic) on machining performance.
Abstract: This paper presents an overview of the recent advances in high performance cutting of aerospace alloys and composite currently used in aeroengine and aerostructure applications. Progress in cutting tool development and its effect on tool wear and surface integrity characteristics of difficult to machine materials such as nickel based alloys, titanium and composites is presented. Further, advances in cutting technologies are discussed, focusing on the role of hybrid machining processes and cooling strategies (MQL, high pressure coolant, cryogenic) on machining performance. Finally, industrial perspectives are provided in the context of machining specific components where future challenges are discussed.

388 citations

Journal ArticleDOI
TL;DR: In this article, the underlying mechanisms of basic challenges, such as variation of chip thickness, high heat stress, high pressure loads, springback, and residual stress based on the available literature are investigated.
Abstract: Titanium alloys are known as difficult-to-machine materials The problems of machining titanium are many folds which depend on types of titanium alloys This paper investigates the underlying mechanisms of basic challenges, such as variation of chip thickness, high heat stress, high pressure loads, springback, and residual stress based on the available literature These are responsible for higher tool wear and worse machined surface integrity In addition, many cutting tool materials are inapt for machining titanium alloys as those materials are chemically reactive to titanium alloys under machining conditions To address these problems, latest techniques such as application of high pressure coolant, cryogenic cooling, tap testing, thermally enhanced machining, hybrid machining, and use of high conductive cutting tool and tool holder have also been discussed and correlated It seems that all the solutions are not yet well accepted in the industrial domain; further advancement in those fields are required to reduce the machining cost of titanium alloys

265 citations