Helmi Attia

Helmi Attia
McGill University / National Research Council of Canada · Mechanical Engineering / Aerospace Structure, Materials and Manufacturing Laboratory

Ph.D.

About

200
Publications
28,683
Reads
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5,267
Citations
Introduction
Additional affiliations
January 2002 - May 2015
McGill University
Position
  • Adjunct Professor of Mechanical Engineering

Publications

Publications (200)
Article
Full-text available
Cryogenic machining gained interest as a clean, and effective cooling technique for machining hard-to-cut materials. Hardened H13 steel is widely used in tool and die applications due to its superior properties at high temperatures. However, its low machinability and post machining tensile residual stress remains a major challenge. A comparative...
Article
Full-text available
The fifth Industrial revolution (I5.0) prioritizes resilience and sustainability, integrating cognitive cyber-physical systems and advanced technologies to enhance machining processes. Numerous research studies have been conducted to optimize machining operations by identifying and reducing sources of uncertainty and estimating the optimal cutting...
Preprint
Full-text available
The fifth Industrial revolution (I5.0) prioritizes resilience and sustainability, integrating cognitive cyber-physical systems and advanced technologies to enhance machining processes. Numerous research studies have been conducted to optimize machining operations by identifying and reducing the sources of uncertainty and estimating the optimal cutt...
Article
Full-text available
In the current study, Ti-6Al-4V (Ti64) and Ti-6Al-7Nb (Ti67) alloys were prepared by vacuum arc melting. The produced samples were then subjected to different heat treatment regimes. The evolved microstructures and their corresponding hardness were investigated. Computerized drilling tests using TiAlN-coated high-speed steel bits were performed to...
Article
Full-text available
Tool Condition Monitoring systems are essential to achieve the desired industrial competitive advantage in terms of reducing costs, increasing productivity, improving quality, and preventing machined part damage. A sudden tool failure is analytically unpredictable due to the high dynamics of the machining process in the industrial environment. Ther...
Article
Full-text available
Abstract: A comparative study was conducted for the machining of two α/β titanium alloys, namely Ti-6Al-4V (Ti64) and Ti-6Al-7Nb (Ti67), using wire electric discharge machining (WEDM). The influence of cutting speed and cutting mode on the machined surfaces in terms of surface roughness (Ra), recast layer (RL), and micro-hardness have been evaluate...
Article
Full-text available
Titanium alloys, due to their distinctive properties, are used in a wide range of modern applications. However, because these alloys are challenging to machine using traditional methods, nonconventional processes are more often utilized. One of the unique thermal machining techniques that offers an effective choice for creating components with the...
Article
Chip segmentation results in a cyclic variation of machining forces, leading to vibration, accelerated tool wear, and surface integrity change. In this paper, experimental and numerical studies were carried out to investigate the effect of chip segmentation on machining-induced residual stresses during the turning of Ti6Al4V. A finite element-based...
Article
Full-text available
The performance of membranes relies on their surface characteristics which degrade due to complex loading during operation. Available studies examine surface properties under uniaxial loading, and limited, if none, are available under various loading conditions. We assess the surface integrity of thin film composite membranes under static and dynam...
Article
Grinding-wheel wear is a critical factor affecting grinding performance and tool cost. Unfortunately, wear tests – particularly with superabrasives – can be notoriously time-consuming. Therefore, a novel lapping-based method is proposed for investigating wear behaviour of the grit-bond system. Wear tests were performed in (i) lapping, (ii) surface...
Article
Full-text available
In the era of the “Industry 4.0” revolution, self-adjusting and unmanned machining systems have gained considerable interest in high-value manufacturing industries to cope with the growing demand for high productivity, standardized part quality, and reduced cost. Tool condition monitoring (TCM) systems pave the way for automated machining through m...
Article
This paper is concerned with an experimental study on grinding titanium alloys using electroplated diamond wheels with focus on wheel wear and its effects on forces, power, and surface roughness. Straight surface grinding experiments were conducted to measure forces, power, surface roughness, and wheel wear. Specific energy values ranging from abou...
Chapter
Hole making represents the majority of the machining operations of composites and hybrid stacked aerospace-structures. Conventional drilling induced part defects, such as delamination of layers and thermal damage of the matrix, are of major economic and safety concerns for aerospace manufacturers. This chapter discusses selected emerging non-conven...
Article
Full-text available
In this paper, the tool wear mechanisms for low-frequency vibration-assisted drilling (LF-VAD) of carbon fiber-reinforced polymer (CFRP)/Ti6Al4V stacks are investigated at various machining parameters. Based on the kinematics analysis, the effect of vibration amplitude on the chip formation, uncut chip thickness, chip radian, and axial velocity are...
Article
A sensor-based hybrid processing approach for tool wear monitoring is presented to overcome the practical limitations of implementing state-of-the-art tool condition monitoring systems in milling processes. It extracts features from vibration signals that are insensitive to the variations in cutting conditions, tool path and interfering noises. A m...
Article
Conventional sinusoidal excitation is commonly used for investigating oscillatory fretting wear. However, in real life applications, the excitation force is random. This work provides a methodology for analyzing random fretting wear damage accumulation. The proposed wear energy characterization is based on the identification of the root mean square...
Article
Fretting wear damage in nuclear power plants is a safety and economic concern. Therefore, understanding the effect of operating conditions on the wear mechanism is essential for optimum design. Fretting tests were performed on a nickel-based alloy 718 against a zirconium alloy in the range 25oC < T < 315oC. The effect of temperature was investigate...
Preprint
Full-text available
In this paper, the tool wear mechanism in low-frequency vibration-assisted drilling (LF-VAD) of carbon fiber reinforced polymer (CFRP)/Ti6Al4V stacks has been proposed using variably machining parameters. Based on the kinematics analysis, the effect of vibration amplitude on the chip formation, uncut chip thickness, chip radian, and axial velocity...
Article
Grinding forces and power are important parameters for evaluating grinding process performance, and they are typically measured in grinding experiments. Forces are typically measured using a load cell or a dynamometer, whereas power is measured using an electrical power sensor to monitor the power of the spindle motor. Direct readings of the measur...
Article
Full-text available
Cryogenic machining is an effective, sustainable cooling approach in machining hard-to-cut materials. In this work, two multi-objective optimization techniques, namely; non-dominated sorting genetic algorithm, and grey relational analysis, were used to optimize the cutting performance during turning Ti-6Al-4V alloys under flood and cryogenic coolin...
Article
Full-text available
Undetected tool wear during drilling of woven composites can cause laminate damage and fiber pull-out and fuzzing, causing subsurface damage. This diminishes the life of the produced part under fatigue loads. Thus, the producing of proper and reliable holes in woven composites requires accurate monitoring of the cutting tool wear level to safeguard...
Article
Superalloys are extensively used in the design of combustor components of aero engines because they can withstand high temperature oxidizing environments, while maintaining their strength. This investigation aims at assessing the tribological characteristic of some combustor components candidate cobalt-based and nickel-based superalloys. Three comb...
Article
Full-text available
A new approach is proposed to predict the thermally-activated dissolution-diffusion wear of carbide tools. Departing from the iterative procedure used for such nonlinear processes, a direct response surface approach that correlates the cutting conditions and wear level to the interface temperature is presented. For prediction of wear evolution, a c...
Article
A new cyber-physical adaptive control system (CPACS) is presented for drilling hybrid stacks. A generalized approach for features recognition, and learning, of spindle power signals was developed for real-time detection of tool wear level. Subsequently, a high fidelity model predicts the drilling forces and the damage at the layers and interfaces o...
Article
Full-text available
Vibration-assisted drilling (VAD) of Ti6Al4V is typically used in the aerospace industry to enhance the performance of the machining process. A mix of continuous and saw-tooth chip formation is associated with VAD of Ti6Al4V. In this paper, a comprehensive experimental study is developed to examine the effect of process parameters on the dominant c...
Article
Full-text available
The superior physical and mechanical characteristics of CFRP/Ti6Al4V stacked structures explain their widespread use in the aerospace industry. However, the unacceptable machining-induced tensile surface residual stresses and reduced surface integrity are the main challenges that are faced in the conventional drilling process. These types of damage...
Article
In nuclear power plants, wear of steam generators, fuel rods and assemblies can have serious economic and safety impact. To reproduce realistic oscillatory fretting wear in laboratory, a novel accelerated random vibration fretting wear test methodology, using Gaussian excitations, is proposed. A new experimental device and protocol were also develo...
Article
Full-text available
The use of lightweight material such as CFRP/Ti6Al4V in stacked structures in the aerospace industry is associated with improved physical and mechanical characteristics. The drilling process of nonuniform structures plays a significant role prior to the assembly operation. However, this drilling process is typically associated with unacceptable CFR...
Article
Full-text available
A continuous curled chip formation with a high thermal load is a critical challenge during conventional drilling process of Ti6Al4V. In addition, adverse side effects will take place on the drilled hole quality, as well as the drill tool performance, which is not acceptable in the aerospace industry. Chip segmentation using low-frequency vibration-...
Presentation
Numerical and experimental investigations for microstructure transformations in the laser surface heat treatment (LSHT) of AISI H13 steel are discussed. The LSHT process is typically used to obtain hardened, wear resistant surface layers with a depth of 0.5 to 1.5 [mm]. In the LSHT process, a laser beam is focused on the workpiece to rapidly heat t...
Article
Recent trends aim at efficient and sustainable cooling strategies for machining hard-to-cut materials. This research is concerned with combining cryogenic cooling and minimum quantity lubrication to benefit from their respective cooling and lubrication capabilities. Fundamental understanding of the flow characteristics of the two jets, their intera...
Article
Full-text available
Carbon fiber-reinforced polymers (CFRP) are widely used in the aerospace industry. A new generation of aircraft is being built using CFRP for up to 50% of their total weight, to achieve higher performance. Exit delamination and surface integrity are significant challenges reported during conventional drilling. Exit delamination influences the mecha...
Article
Tool condition monitoring (TCM) is crucial for manufacturing systems to maximize productivity, maintain part quality, and reduce waste and cost. Available TCM systems mainly depend on data-driven classical machine learning methods to analyze different sensors’ feedback signals for tool condition prediction. Despite their applicability for high proc...
Article
A hybrid modeling approach based on computational fluid dynamics (CFD) and finite element method (FEM) is presented to simulate and study cryogenic machining (CM) of Ti-6Al-4V alloy. CFD analysis was carried out to study the characteristics of the fluid flow and heat transfer process of liquid nitrogen (LN2) jet used as a coolant in turning operati...
Article
Full-text available
The drilling of carbon fiber-reinforced polymers (CFRP) and Ti6Al4V alloy stacked materials play a significant role in the aerospace industry’s ability to achieve improved machinability and assembly. Conventional drilling has resulted in various challenges such as CFRP delamination, unacceptable hole accuracy, and high tool wear. In addition, high...
Article
Full-text available
Pattern recognition techniques have been implemented in real-time tool condition monitoring (TCM) systems to improve their robustness and reliability. The performance and accuracy of these techniques vary depending on their algorithm and the dataset properties. This research benchmarks six pattern recognition techniques to optimize the learning eff...
Article
An integrated tool condition monitoring system, based on a novel signal processing approach, for online prediction and prevention of tool chipping in intermittent turning is presented. It identifies the unstable crack propagation features of the prefailure phase, independent of the cutting parameters and workpiece material. A correlation between th...
Article
Unmanned manufacturing systems has recently gained great interest due to the ever increasing requirements of optimized machining for the realization of the fourth industrial revolution in manufacturing ‘Industry 4.0’. Real-time tool condition monitoring (TCM) and adaptive control (AC) machining system are essential technologies to achieve the requi...
Article
Full-text available
Titanium alloys are widely used in aerospace applications due to their physical and mechanical properties. However, their poor machinability remains the main challenge to improve the productivity and the surface quality. Cryogenic machining recently gained interest as a clean and economical cooling technique. It becomes a promising candidate for ap...
Article
Full-text available
Titanium-based metal matrix composite (T-MMC) is a relatively new material with increasing demand in different industries particularly in aerospace. Yet, there is a significant lack of knowledge regarding its machinability. Tool wear mechanisms of cBN inserts during turning of TiMMCs including adhesion, abrasion, chemical interactions, and their ef...
Article
In high-speed cutting processes, late replacement of defective tools may lead to machine breakdowns and badly affect the product quality, which subsequently lead to scrap parts and high process costs. Accurate tool condition detection is essential to achieve high level of competitiveness via increasing process productivity and standardizing the qua...
Article
Full-text available
Minimum quantity lubrication has gained recent importance in high speed machining. However, more understanding and optimization of the MQL parameters remains a challenge to improve its performance. The main objective of this paper is to study the environmental impact and the machining performance of Minimum Quantity Lubrication (MQL) in milling of...
Article
This paper reports an experimental study on grinding of chromium carbide coatings using electroplated diamond wheels. The work was motivated by machining carbide coatings in gas turbine engine applications. The objective is to explore the process conditions and parameters satisfying the ground surface quality requirements. Surface grinding experime...
Article
This paper reviews recent advances in constitutive and friction data and models for simulation of metal machining. Phenomenological and physically-based constitutive models commonly used in machining simulations are presented and discussed. Other topics include experimental techniques for acquiring data necessary to identify the constitutive model...
Conference Paper
Titanium alloys are widely used in aerospace and medical applications due to their physical and mechanical properties. However, they are classified as difficult-to-cut materials due to their high strength, low thermal conductivity and chemical reactivity at elevated temperatures. Their machinability is characterized by poor surface integrity and sh...
Article
Orbital drilling of composites was investigated to observe hole surface integrity in terms of surface roughness, delamination, surface burning, and geometric accuracy. Experiments were conducted with a brazed single layer diamond tool of ball-end geometry to drill 220 holes. Cutting forces and temperatures were measured. Micro-observations were mad...
Article
Residual stresses (RS) induced by machining control a component's resistance to progressive failure. It is crucial to identify favorable cutting conditions that promote fatigue-inhibiting compressive RS while preserving other aspects of surface integrity. An extensive investigation was performed in the finish turning regime for two aerospace grade...
Conference Paper
Tool failure remains one of the most challenging phenomena in machining that affects the productivity and product quality, and hence the cost. In high feed rough milling operations of hard-to-cut materials, chipping and breakage have been observed as the dominant failure modes of the end mill cutters. Most of the work in the open literature is focu...
Conference Paper
Full-text available
Drilling of stacks poses great challenges due the heterogeneity and abrasiveness of the composites, the chip evacuation through the stack, in addition to the difference in properties between the metallic and the composite materials. The objective of this paper is to investigate the effect of drilling conditions such as tool material and geometry an...
Conference Paper
An analysis for a robotized grinding process of aerospace Titanium high pressure compressor blades was performed. In this process, the blade was grabbed on the robotic arm. A Scotch-Brite grinding wheel, on a pneumatic actuator, was used to grind the edges of the blades. The objective of this research work was to identify the major factors that inf...
Article
Titanium Metal Matrix Composite (Ti-MMC) is a relatively new class of material, which has high potential applications in the aeronautical and biomedical sectors. Similar to titanium alloys, Ti-MMC produces segmented chips, which are characterized by Adiabatic Shear Bands (ASB). Transmission Electron Microscopy (TEM) observations were performed and...
Article
Cryogenically assisted manufacturing processes are emerging as environmentally-benign, toxic-free, hazardless operations, producing functionally superior products. This paper presents an overview of major cryogenic manufacturing processes, summarizing the state-of-the-art and significant developments during the last few decades. It begins with a su...
Article
The heat transfer from rotating workpieces in dry and laser-assisted machining turning operations has significant effect on the part temperature field and consequently the cutting forces, microstructure evolution and the thermoelastic behaviour of the workpiece. Process modelling and simulation require knowing the convective coefficient of heat tra...
Article
A new hybrid oscillatory orbital process, using superabrasive diamond tools, was developed for drilling FRP composites. Effects of grain size and tool geometry on forces, temperatures, and surface integrity were experimentally investigated. With proper selection of cutting conditions and process variables, the limitations of conventional orbital dr...
Article
A survival analysis methodology is employed through a novel approach to model the progressive states of tool wear under different cutting conditions during machining of titanium metal matrix composites (Ti-MMCs). A proportional hazards model (PHM) with a Weilbull baseline is developed to estimate the reliability and hazard functions of the cutting...
Article
Full-text available
Utilizing the full tool life capacity of cutting tools has always been a concern, due to the considerable costs associated with suboptimal replacement of tools. Reliable reuse of worn inserts could significantly reduce machining costs. This study aims at estimating the remaining useful life of worn cutting inserts under multiple cutting parameters...
Article
A process for grinding deep profiled slots in a nickel-based alloy with electroplated cubic boron nitride (CBN) wheels and straight oil is presented. These slots were prepared by this process for further grinding with electroplated CBN quills to generate the final fir-tree slots in gas turbine disks. Fir-tree slots are usually machined using broach...
Conference Paper
A recent and promising technique to overcome the challenges of conventional drilling is vibration-assisted drilling (VAD) whereby a controlled harmonic motion is superimposed over the principal drilling feed motion in order to create an intermittent cutting state. Two additional variables other than the feed and the speed are introduced, namely the...
Article
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, titani...
Article
Full-text available
Reliable force and temperature prediction in drilling of fibre-reinforced polymers (FRPs) is the key to controlling drilling-induced damage. A novel hybrid analytical-numerical model is developed to capture time-varying forces and temperatures during transient and steady-state drilling of FRPs. Although the generalized force model is calibrated usi...
Article
Cobalt-based superalloys are used in aero-engine combustor components due to their high strength and wear resistance at elevated temperatures. The objective of this investigation is to study the role of the surface oxide formed during the fretting process on the tribological behavior of this class of materials, at temperatures up to 550 °C. The inv...
Article
Full-text available
Little practical results are known about the cutting tool optimal replacement time, specifically for machining of composite materials. Due to the fact that tool failure represents about 20% of machine down-time, and due to the high cost of machining, in particular when the work piece’s material is very expensive, optimization of tool replacement ti...
Conference Paper
Full-text available
Force is considered to be one of the indicators that best describe the machining process. Measured force can be used to evaluate the quality and geometric profile of the machined part. In this paper, a combinatorial optimization approach is used to characterize the effect of force on the quality of a machined part made of Carbon Fiber Reinforced Po...
Article
Full-text available
Limited information is available on the effect of Minimum Quantity Lubrication (MQL) parameters (oil flow rate OFR, air flow rate AFR, nozzle orientation and distance from the cutting zone) on flow characteristics. ‘Particle Image Velocimetry’ and ‘Phase Doppler Anemometry’ flow visualization methods were used to define the optimal MQL jet for bett...
Article
Composite materials are widely used in the aerospace industry. It is a great challenge to achieve high-quality parts with reduced damage level when drilling the faces of composites. This is due to several factors including the heterogeneity of the material, its sensitivity to heat, and its abrasiveness. The objective of this study was to characteri...
Article
1Defects associated with drilling of fiber reinforced polymers (FRPs) are of major economic and safety concerns for aerospace manufacturers. Delamination of layers and thermal damage of the matrix are the most critical defects associated with drilling of FRP laminates, which can be avoided by keeping the drilling forces and temperatures below some...
Article
1Conventional drilling of modern super alloys and composite material induces high stresses in the vicinity of drilled holes along with high thrust forces which lead to problems in terms of hole quality and accuracy as well as increased tool wear. A recent and promising technique to overcome these challenges is to introduce vibration assistance in t...
Article
Full-text available
Carbon fiber reinforced polymer (CFRP) is an important composite material. It has many applications in aerospace and automotive fields. The little information available about the machining process of this material, specifically when routing process is considered, makes the process control quite difficult. In this paper, we propose a new process con...
Article
An experimental study was undertaken to explore the conditions and performance on rough and finish grinding fir-tree root forms of turbine blades made of a nickel-based alloy using vitrified CBN wheels and water-based grinding fluid. This work was motivated by switching the grinding of fir-tree root forms from grinding with conventional abrasive wh...
Article
Optimum selection of cutting conditions in high-speed and ultra-precision machining processes often poses a challenging task due to several reasons; such as the need for costly experimental setup and the limitation on the number of experiments that can be performed before tool degradation starts becoming a source of noise in the readings. Moreover,...
Conference Paper
Full-text available
This paper is concerned with the reliable calibration of the grinding power model. The power model used in the present paper is expressed by formulae with grinding parameters as input arguments, and a number of model constants representing a given wheel, workpiece, and grinding fluid combination. The model constants are calibrated using measured gr...
Conference Paper
Full-text available
Metal matrix composites (MMCs), as a new generation of materials; have proven to be viable materials in various industrial fields such as biomedical and aerospace. In order to achieve a valuable modification in various properties of materials, metallic matrices are reinforced with additional phases based on the chemical and/or physical properties r...