Links Between Machining Parameters and Surface Integrity in Drilling Ni-Superalloy

In aerospace industry, the manufacturing of critical parts (high energy components) requires an important validation process to guarantee the quality of the produced parts, and thus their fatigue lifecycle. Globally, this validation consists in freezing the cutting conditions using metallurgical analysis or fatigue trials, and a test on the first article. This process is extremely complex and expensive. In this way establishing the correlation between the cutting conditions and the surface integrity will help us to optimize the manufacture of those parts. In this article, by the means of an experimental method, we define a domain of validation by combining the cutting conditions according to the classic criteria established by AFNOR E66-520 norm (Couple-Tool-Material) and the criteria of surface integrity for the drilling of a Nickel-base superalloy. The experimental device consists in drilling a Ø15.5 mm hole on a 3-axis milling centre instrumented by a 4 components Kistler dynamometer (Fx, Fy, Fz and Mz), a spindle power sensor “Watt-pilote” and three accelerometers placed following the directions X, Y and Z. Scanning Electron Microscopy (SEM) observations, micro-hardness tests and topographic measurements with an optical profilometer, are carried out to characterize the metallurgical state of the holes manufactured. Finally, correlations were respectively made between the cutting conditions, the recorded signals and the metallurgical state of the holes

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

Vibrations d'usinage en tournage intérieur fortement interrompu, d'une pièce produite en grande série

Dans une production grande série de pièces automobiles, des vibrations d’usinage ont été observées. Les modèles spécifiques au tournage intérieur de pièces cannelées étant rares, un modèle de broutement a été développé. De plus, les défauts de concentricité ont été pris en compte. Suite à l’analyse du process actuel, il est développé ici quelques modèles simples permettant d’estimer les efforts de coupe en jeu et les fréquences propres de vibration de la pièce, avec ou sans effet gyroscopique. Le modèle dit de «semi-discrétisation» est utilisé afin d’estimer l’influence de l’amplitude et de l’orientation angulaire de l’excentration par rapport aux cannelures. Les résultats obtenus par les modifications réalisées sur le process actuel sont ensuite présentés. Enfin, des modélisations supplémentaires ont été réalisées afin de prédire l’influence sur les vibrations d’une modification de la forme de la pièce et de l’utilisation de conditions UGV

A diffusion model decomposition of the effects of alcohol on perceptual decision making

RATIONALE: Even in elementary cognitive tasks, alcohol consumption results in both cognitive and motor impairments (e.g., Schweizer and Vogel-Sprott, Exp Clin Psychopharmacol 16: 240-250, 2008). OBJECTIVES: The purpose of this study is to quantify the latent psychological processes that underlie the alcohol-induced decrement in observed performance. METHODS: In a double-blind experiment, we administered three different amounts of alcohol to participants on different days: a placebo dose (0 g/l), a moderate dose (0.5 g/l), and a high dose (1 g/l). Following this, participants performed a "moving dots" perceptual discrimination task. We analyzed the data using the drift diffusion model. Model parameters drift rate, boundary separation, and non-decision time allow a decomposition of the alcohol effect in terms of their respective cognitive components, that is, rate of information processing, response caution, and non-decision processes (e.g., stimulus encoding, motor processes). RESULTS: We found that alcohol intoxication causes higher mean RTs and lower response accuracies. The diffusion model decomposition showed that alcohol intoxication caused a decrease in drift rate and an increase in non-decision time. CONCLUSIONS: In a simple perceptual discrimination task, even a moderate dose of alcohol decreased the rate of information processing and negatively affected the non-decision component. However, alcohol consumption left response caution largely intact

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

Analyse et réduction des vibrations d'usinage d'une pièce automobile produite en grande série

Dans un contexte industriel de production grande série de pièce automobiles il a été observé qu'apparaissaient de façon sporadique, mais persistante, des problèmes de vibration. Cela a imposé un contrôle systématique des pièces produites. Les phénomènes en question ici, dit de vibrations forcées et auto-entrenues, a déjà fait l'objet de publications scientifiques, mais peu de modèles proposés sont adaptés à notre cas précis : il s'agit du tournage intérieur avec coupe fortement interrompue. De plus, la présence, inévitable en production grande série, de défauts répartis plus ou moins aléatoirement, représente un facteur majeur ici dans l'apparition du phénomène. Le travail présenté ici consiste en premier lieu à identifier par des mesures les nombreux facteurs susceptibles de contribuer à l'apparition du phénomène de vibration. Des modélisations vibratoires adaptées à notre cas, ont été ensuite réalisées afin de préciser certaines hypothèses issues de l'analyse des mesures. En conclusion, il est montré l'importance fondamentale des défauts (outils, pièce, machine) et de leurs cumuls sur l'apparition des phénomènes. Des améliorations du process d'usinage ont été mises en œuvre industriellement et des pistes d'amélioration ont été mises à jour

Impact of disturbed drilling conditions on the surface integrity of a Nickel-base superalloy

Manufacturing critical parts for aerospace industry requires an important validation process to guarantee the quality of the produced components, and thus their fatigue life. Even with the best cutting conditions, disturbances can occur during the process and may have a direct impact on metallurgical quality. Through an experimental approach, this work presents the impact, during machining, of a lubricant interruption on the surface integrity and on the Process Monitoring signals. Finally a correlation between the thickness of the thermo-mechanically affected layer and the cutting power is made

Investigation of tool failure modes and machining disturbances using monitoring signals

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 out on tool condition. The aim of this paper is to define a monitoring approach able to detect the tool condition and machining disturbances. The main failure modes characterizing this particular Nickel base drilling and the apparition of embedded chips over the machined surface were identified. By experimental techniques, cartography of failure modes was performed. The results show that flank wear and notch are the main failure modes limiting the tool life. For some cutting conditions, the tool failure occurs after the first hole due to the important cutting forces. Some interesting combinations are made between the spindle current/accelerometers/ thrust force and flank wear, tool breakage and notch. Before these correlations, a detailed signal analysis was performed, considering different disturbing phenomena, such as chips evacuation problem. Finally, a “synopsis” for process monitoring is proposed, considering the analyzed phenomena

Two different Oenococcus oeni lineages are associated to either red or white wines in Burgundy: genomics and metabolomics insights

Oenococcus oeni is the bacterium most often associated with spontaneous malolactic fermentation (MLF) of wine. During MLF, malic acid is transformed into lactic acid and several metabolites are modified, modulating wine’s total acidity and improving its sensory properties. Previous works have suggested that certain genetic groups of O. oeni strains are associated to different kinds of products. In the present study we have spotted two groups of strains isolated mainly from Burgundy wines, one associated to red wines and the other to white wines. Sequencing 14 genomes of red and white wine strains revealed that they share a common ancestor that probably colonised two different substrates –red and white wine-associated environments–, diverging over time and disseminating to various regions. Their capacity to perform MLF and modify the volatile profile of wine was determined by fermenting a chardonnay wine and analysing its volatile fraction with a non-targeted metabolomics approach by GC-MS. The strains had a different impact on the volatile composition depending on their group of origin. These results show for the first time a correspondence between the product of origin of the strains and the volatile profile of the wines they produce. Furthermore, the genetic features that might be implied in these different phenotypes are examined

Testing theories of post-error slowing

People tend to slow down after they make an error. This phenomenon, generally referred to as post-error slowing, has been hypothesized to reflect perceptual distraction, time wasted on irrelevant processes, an a priori bias against the response made in error, increased variability in a priori bias, or an increase in response caution. Although the response caution interpretation has dominated the empirical literature, little research has attempted to test this interpretation in the context of a formal process model. Here, we used the drift diffusion model to isolate and identify the psychological processes responsible for post-error slowing. In a very large lexical decision data set, we found that post-error slowing was associated with an increase in response caution and—to a lesser extent—a change in response bias. In the present data set, we found no evidence that post-error slowing is caused by perceptual distraction or time wasted on irrelevant processes. These results support a response-monitoring account of post-error slowing