Experimental characterization of behavior laws for titanium alloys: application to Ti5553

The aim of this paper is to study the machinability of a new titanium alloy: Ti-5AL-5Mo-5V-3CR used for the production of new landing gear. First, the physical and mechanical properties of this material will be presented. Second, we show the relationship between material properties and machinability. Third, the Ti5553 will be compared to Ti64. Unless Ti64 is α+β alloy group and Ti5553 is a metastable, we have chosen to compare these two materials. Ti64 is the most popular of titanium alloys and many works were been made on its machining. After, we have cited the Ti5553 properties and detailed the behavior laws. They are used in different ways: with or without thermal softening effect or without dynamic terms. The goal of the paper is to define the best cutting force model. So, different models are compared for two materials (steel and titanium alloy). To define the model, two methods exist that we have compared. The first is based on machining test; however the second is based on Hopkinson bar test. These methods allow us to obtain different ranges of strain rate, strain and temperature. This comparison will show the importance of a good range of strain rate, strain and temperature for behavior law, especially in titanium machining

Experimental study of coated carbide tools behaviour: application for Ti-5-5-5-3 turning

The goal of this paper is to study the relation between the input data (conditions and geometry of cut) and answers (wear of tool, forces and cutting temperatures) when machining the Ti-5-5-5-3 alloy treated. This study has shown that the cutting process is different and that the slip forces are preponderates. Compared with other materials, the specific cutting pressure is higher and does not vary according to the cutting speed but depend on feed rate. Moreover, both edge preparation and feed rate have an influence on cutting force direction. Besides, cutting temperatures are high and almost similar to those provided by high speed machining with low cutting speed. Finally, we have shown that failure modes are different from those obtained when machining other titanium alloys. Built-up edge is the most deteriorating phenomenon and no flank wear was met in our study context

Identification of influent factors on surface integrity in nickel-base superalloy drilling

For the critical rotating components in aeronautical industry, the metallurgical quality achieved after machining conditions could determine their mechanical behaviour in fatigue. To guarantee this quality, the tools, materials and cutting conditions are frozen during the validation process by a cutup part following by an acceptable surface integrity. Even with the fixed parameters, perturbations can occur during the process and may have a direct impact over the metallurgical quality through the apparition of anomalies, which could reduce the calculated fatigue life. The aim of this study is to define a Process Monitoring technique able to detect the thickness affected by the machining taking into account the flank wear effect

An Experimental Investigation of Hot Machining with Induction to Improve Ti-5553 Machinability

The manufacturing of aeronautic parts with high mechanical properties requires the use of high performance materials. That’s why; new materials are used for landing gears such as the titanium alloy Ti-5553. The machining of this material leads to high cutting forces and temperatures, and poor machinability which requires the use of low cutting conditions. In order to increase the productivity rate, one solution could be to raise the workpiece initial temperature. Assisted hot machining consists in heating the workpiece material before the material removal takes place, in order to weaken the material mechanical properties, and thus reducing at least the cutting forces. First, a bibliography review has been done in order to determine all heating instruments used and the thermal alleviation that exists on conventional materials. An induction assisted hot machining was chosen and a system capable to maintain a constant temperature into the workpiece during machining (turning) was designed. Trails permit to identify the variation of cutting forces according to the initial temperature of the workpiece, with fixed cutting conditions according to the TMP (Tool-Material-Pair) methodology at ambient temperature. Tool life and deterioration mode are identified notably. The results analysis shows a low reduction of specific cutting forces for a temperature area compatible with industrial process. The reduction is more important at elevated temperature. However, it has consequences on quality of the workpiece surface and tool wear

The relationship between the cutting speed, tool wear, and chip formation during Ti-5553 dry cutting

Over the past several years, titanium alloys have been increasingly used in aeronautics. However, they are considered to have poor machinability. The Ti-5553 near-beta titanium alloy is used in aeronautics to replace Ti-64 and for the production of structural parts, such as landing gears. Due to the low thermal properties and the high mechanical properties presented in this work, this alloy is considered difficult to machine. This work is devoted to understanding the relationship between the chip formation, the cutting process, and the tool wear. The first section studies the evolution of the tool wear. The tests show that tool wear occurs in three steps mainly due to the cutting process and the chip formation. To clarify these points, a section is dedicated to the chip formation and cutting processes. An analytical model is also used to quantify stresses, temperatures, and friction inside the workpiece material and at the tool/chip interface. Chip formation is commonly studied using a tool without wear, which can affect the cutting tool geometry. To verify chip formation and the cutting process during machining, a section describes the chip formation and the cutting processes using worn tools

Identification of tool failure modes in drilling Udimet® 720 superalloy

The ACCENT Project (FP7- AAT- 2007- RTD-1) will allow the European Aero Engine manufacturers to improve their competitiveness by applying adaptive control techniques to the manufacturing of their components. For the critical rotating parts of aircraft engines, the surface integrity generated after machining is a key factor on the life cycle. In this context, one particular attention has to be carried on tool condition. The aim of this paper is to identify the main failure modes characterizing this particular Nickel base drilling. By experimental techniques, cartography of failure modes was realized. The results show that flank wear and notching are the main failure modes limiting the tool life. For some cutting conditions, the tool failure arrives after the first hole due to the important cutting forces. Some interesting associations are made between the spindle current/accelerometers/ thrust force and flank wear, tool breakage and notching

Behaviour laws comparison for titanium alloys machining: Application to Ti5553

The aircraft industry uses materials more and more efficient. This trend affects the majority of parts such as structure parts. Titanium alloy (Ti-5AL-5Mo-5V-3CR) is now used for the production of landing gear. There are many goals in this paper. First, the physical and mechanical properties of the material will be presented. Secondly, we show the relationship between material properties and machinability. Third, the Ti5553 will be compared to Ti64. The Ti64 is a+b alloy group and Ti5553 is a metastable beta but we have chosen to compare these two materials. Ti64 is the most popular of titanium alloys and many of works were been made on its machining. After, we have cited the Ti5553 properties and detailed the behaviour laws. They are used in different ways, with or without thermal softening effect or without dynamic terms. We have to define the best model to use in cutting force model. Differents models are compared for two materials (steel and titanium alloy). To define the model, two methods exist that we have compared. The first is based on machining test however the second on Hopkinson bar test. These methods allow us to obtain different ranges of strain rate, strain and temperature. This comparison will show the importance of a good range of strain rate, strain and temperature for behaviour law, especially in titanium machining

Influence de la température sur l’usinabilité du Ti-5-5-5-3

The realization of aeronautic parts with strong mechanical properties requires the use of high performance materials. That’s why, some new materials are used for landing gears as refractory titanium (as Ti-5-5-5-3). The machining of this material leads to high cutting forces and temperatures. So, it is necessary to use low cutting conditions on the industrial machining process. In order to increase the productivity, it is possible to increase the initial temperature of the workpiece. Hot machining is a new research track. The principle consists in heating material before machining it, in order to take advantage of its mechanical properties reduction. First, studying the state of the art permit us to determine all heating instruments used and the thermal alleviation that exists on conventional materials. A heating by induction was chosen and a system capable to maintain a constant temperature into the workpiece during machining (turning) was conceived. The measure of the temperature is achieved in the setup of the workpiece by thermocouples and by thermography camera. Trails permit to identify the variation of cutting forces according to the initial temperature of the workpiece, with fixed cutting conditions according to the TMP (Tool- Material-Pair) methodology at ambient temperature. Tool life and deterioration type are identified notably. The results analysis shows a low reduction of specific cutting forces for a temperature area compatible with industrial process. The reduction is more important at elevated temperature. However, it has bad consequences on quality of the workpiece surface (oxidation, problem on surface integrity and mechanical properties degradation). In perspective, different ways of heating are studied to permit a localized and more effective heath compatible with the industrial application

Determination of Sphingosine-1-Phosphate in Human Plasma Using Liquid Chromatography Coupled with Q-Tof Mass Spectrometry

Evidence suggests that high-density lipoprotein (HDL) components distinct from cholesterol, such as sphingosine-1-phosphate (S1P), may account for the anti-atherothrombotic effects attributed to this lipoprotein. The current method for the determination of plasma levels of S1P as well as levels associated with HDL particles is still cumbersome an assay method to be worldwide practical. Recently, a simplified protocol based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the sensitive and specific quantification of plasma levels of S1P with good accuracy has been reported. This work utilized a triple quadrupole (QqQ)-based LC-MS/MS system. Here we adapt that method for the determination of plasma levels of S1P using a quadrupole time of flight (Q-Tof) based LC-MS system. Calibration curves were linear in the range of 0.05 to 2 µM. The lower limit of quantification (LOQ) was 0.05 µM. The concentration of S1P in human plasma was determined to be 1 ± 0.09 µM (n = 6). The average accuracy over the stated range of the method was found to be 100 ± 5.9% with precision at the LOQ better than 10% when predicting the calibration standards. The concentration of plasma S1P in the prepared samples was stable for 24 h at room temperature. We have demonstrated the quantification of plasma S1P using Q-Tof based LC-MS with very good sensitivity, accuracy, and precision that can used for future studies in this field

Design for additive manufacturing including machining constraints: A case study of topology optimization including machining forces

Metal additive manufacturing is a major field of study and innovation. In aerospace industry a lot of effort is made to modelise and optimize the designs. In this context, despite all efforts, metal additive manufacturing (especially SLM) still produce part generally considered as raw parts which still have some surfaces to be machined in order to obtain the required geometrical quality. Despite sometimes, great complexity and cost related to the finishing process, the machining stage is never taken into account in the design process, especially using the topological optimization approach. In this paper, a new Design for Additive Manufacturing (DFAM) method is proposed in order to optimize the design stage including topological optimization, machining, geometrical and mechanical constraints. It is shown on a typical aeronautical part that cutting forces may be the greatest forces during all the part life-time. Using 2 different topological optimization software (Inspire / Abaqus Tosca) it is shown that it is possible to consider most of the machining constrains to only slightly modify the initial design and thus simplify the machining stage and reduce possible failure during machining. Finally, machining test, geometrical accuracy control and pressure test validate the approach