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The present article addresses solidification parameters, and includes analyses of the macrostructure and microstructure in the light of the results obtained from the thermal analysis, from which it is possible to conclude that undercooling (TS) and recalescence (TR) temperatures increase with the initial increase in titanium (Ti) concentration. If the concentration reaches approximately 0.25%, a rapid decrease in these temperatures is observed. Thereafter, the temperatures increase again with the further increase in Ti concentration, and eventually become constant. These temperatures also vary depending on the superheating and casting temperature. The ∆T parameter (i.e., TS − TR) decreases with the Ti concentration and, from a concentration of around 0.20% Ti, this parameter becomes zero. The grain size decreases with the Ti concentration. If the concentration exceeds about 0.20%, the grain size becomes the minimum. Another parameter to be considered is the interaction between the grain refiner and the traces of other metals in the base Al alloy. For example, Al-4%B can react with traces of Ti that may exist in the base alloy, leading to the reaction between boron (B) and Ti to form TiB2. Grain refinement is achieved primarily with TiB2 rather than AlB2, or both, depending on the Ti content in the given alloy.

The residual stresses state that a mechanical part obtained after machining is a crucial factor that impacts its in-service performance. This stress state is influenced by the thermomechanical loads exerted on the parts during the machining process, which are, in turn, determined by the tool parameters, process, and machining conditions. The aim of the present research was to anticipate how the cutting tool’s edge radius, rake angle, and clearance angle would affect the forces, temperature, and residual stresses induced while orthogonally cutting aluminum AA6061-T6. To achieve this, two-dimensional DEFORM™ software was utilized to develop a finite element model. The residual stresses trend results obtained demonstrated that rake angles of 0° and 17.5–20° values with a small edge radius (5 to 10 µm) and clearance angles of 7 and 17.5° values gave higher compressive stresses. The obtained simulated results were in good agreement with the experiments. The cutting forces, the temperature, and the maximum and minimum machining-induced residual stresses were found to be influenced more by the tool edge radius and the tool rake angle. The influence of the clearance angles on the above-mentioned machining responses was the least. Residual stresses can have a significant impact on the in-service performance of machined parts. The obtained results will help engineers select or design tools that promote a desired surface integrity during machining. This task is not obvious in practice because of difficulties in measuring residual stresses and also because the machining parameters and the tool geometry parameters have different and opposite impacts on thermo-mechanical loads, productivity, and on machining induced residual stresses.

PurposeThis paper studies the integration of production and maintenance planning for an unreliable production system subject to gradual deterioration. The goal of this planning is to optimize production and maintenance while reducing workers' exposure to silica dust. The objective will therefore be to offer manufacturers a production strategy that minimizes the total cost of production while considering the health of employees.Design/methodology/approachAdequate prevention methods are determined and integrated into the granite transformation production system, which evolves in a stochastic environment. With the failure rate of the dust reduction unit being a function of its degradation state, the authors solve the optimization problem using stochastic dynamic programming in the context of nonhomogeneous Markov chain.FindingsThe resulting planning strategy shows that one can manage stock optimally while ensuring a healthy environment for workers. It ensures that crystalline silica prevention equipment is available and effective and defines the production rate according to a critical threshold, which is a function of the age of the dust reduction unit.Research limitations/implicationsThis article illustrates that it is possible to integrate silica dust reduction measures into production planning while remaining optimal and ensuring the health of operators. In the present study, the machined granite was assumed to be a natural granite, and production takes place in a closed environment.Originality/valueThe originality of this work lies in its development of an optimal joint production and maintenance strategy, which considers limits of exposure to crystalline silica. An optimal production and maintenance control policy considering employees' health is therefore proposed.

The first part of this work was to explore the development of residual stresses in I-4 and V-6 engine blocks made of B319.1 alloy using the sectioning technique. The results suggest that there is refinement in the microstructure due to an increase in cooling rate along the cylinder. The developed residual stresses were found to be tensile for both I-4 and V-6 engine blocks. Furthermore, the variation in the developed residual stresses was found to be insignificant. The results also indicate that air cooling produced the highest residual stresses compared to warm water and cold water quenching. Solution heat treatment and freezing (−30 oC) led to the maximum amount of residual stress relaxation where 50% of the residual stresses were reduced after the solution heat treatment step. Aging time and aging temperature are directly proportional to the residual stress relaxation. Correlations between alloy hardness and the evolved residual stress have been established. In the second part, residual stresses were obtained from the milled surface of a rectangular workpiece (30 × 172 × 302 mm, five blocks/alloy for five studied alloys). Thirteen layers of material were removed from each block, where each layer consisted of ten paths, and the depth of cut was 1.35 mm, using fresh and dull inserts. In this case, measurement of residual stresses was carried out on the blocks at the end of the milling process, using the X-ray technique. All stresses were of tension-type compared to compression type in the un-machined shoulders. Due to the high applied forces required when using dull inserts, the resulting residual stresses were almost twice that generated by new inserts in spite of the large difference in the machining distance.

The present research study aimed to investigate the influences of turning environments and parameters on machining temperature (MT), machining forces (MFs), and axial surface residual stresses (ASR...

In this study, the results pertaining to the influence of various metallurgical parameters on the tensile properties of Al–Si–Cu–Mg 354-type casting alloys are presented. This is discussed with an emphasis on acquiring an insight regarding the mechanical limits of Al–Si–Cu–Mg 354-type alloys in the context of these parameters, and to obtain an understanding of the effects of the addition of nickel and/or zirconium on alloy 354 with respect to the mechanical properties obtained at high temperature (155 °C and 300 °C for holding times at temperature ranging from 10 to 100 h). Based on an analysis of the results obtained, the following conclusions may be drawn. The results show that additions of Zr and Zr + Ni increase the high-temperature tensile properties, in particular for the alloy containing 0.2 wt% Zr + 0.2 wt% Ni, which exhibits an increase of more than 30% in the tensile properties at 300 °C compared with the base 354 alloy. In other words, the addition of 0.4 wt% Ni + 0.4 wt% Zr to the 354 alloy is not sufficient to resist softening at 300 °C/100 h (cf. UTS: 52 MPa, YS: 45 MPa, %El: 23% with UTS: 361 MPa, YS: 343 MPa, %El 1.23%, observed after T6 treatment). The addition of 0.4 wt% Ni to alloy 354 leads to a decrease in the tensile properties, compared to the base alloy. This decrease may be attributed to a Ni–Cu reaction which could interfere with the formation of the Al2Cu strengthening precipitates, thereby affecting the age hardening process. As a consequence, percentage elongation increases with the testing temperature, from as-cast to T6-treated samples tested at high temperature (155 °C and 300 °C, respectively). In summary, the best high-temperature tensile properties are displayed by the alloy containing 0.2 wt% Zr + 0.2 wt% Ni.

The present research work aimed at evaluating the effect of Ce and La rare earth (RE) additions on the formation of intermetallics in an Al-8.0Si-2.4Cu-0.4Mg-0.4Fe-0.6Mn-0.15Ti alloy (coded D0). These alloys were solidified at a rate of ~0.7°C/s. Microstructural analyses revealed the presence of two types of RE-containing intermetallic phases: (i) a gray phase with a fixed composition of Al21Ti2RE(Ce/La) and (ii) a white RE-containing intermetallic phase stemming from the reaction of the RE (Ce/La) with Si, Fe, and Cu. The present study aimed as well at studying the influence of the additions of Ce and La elements (0–1.0%) on the high-temperature (250 °C) tensile properties of the Al-8.0Si-2.4Cu-alloys. The results showed that T6-treated alloys, Sr-modified alloys, or those containing Ce/La exhibited UTS values comparable to the solution heat-treated, T5, and T7 alloys.

In the current study, a series of forty-two cast Al–Si–Cu–Mg -based alloys with additions of transition metals (V, Cr, Ni) and rare earth (RE) metals (La, Ce) were prepared and mechanically tested in the as-cast, T5, T6 and T7 heat treatment conditions. The microstructures were investigated using optical microscopy, scanning electron microscopy (SEM) and electron probe microanalysis (EPMA). The volume fraction, aspect ratio, and roundness of second phase constituents were determined by ImageJ analysis software. The microstructural observations show that the RE elements have a greater impact on the microstructure of cast alloys, resulting in the formation of new types of intermetallic phases containing RE, Al–Si–Cu–RE and Al–Ti–RE. With regard to the mechanical properties, it was found that the highest strength of the casting alloys was found with 0–0.2 wt% addition of Ce/La. However, the addition of more than 0.2 wt% induced a detrimental effect on the mechanical properties due to precipitation of a high volume fraction of insoluble intermetallic compounds containing RE. Excessive addition of RE elements leads to the formation of a coarse intermetallic compound along the grain boundary. Besides, RE elements have a marginal modification effect in terms of changing the morphology of the eutectic Si particles.

The present study was performed on A356 and A413 alloys containing (6–11) %Si. Measured amounts of high-purity La and Ce were added to the molten metal that was allowed thereafter to solidify at a slow rate (~ 0.8 °C/s). The results show that the addition of RE metals (La + Ce) up to 3 wt% leads to an increase in the freezing range through an increase in the melting point of the non-modified alloys by 12 °C, with a decrease in the Al–Si eutectic temperature, by 8 °C, respectively, at 3 wt% addition, regardless of the alloy Si content. Although 0.2% Ce is sufficient to drop the Te2 by about 6 °C, 1.5% Ce is required to raise the Tα2 by about 8–10 °C, regardless of the alloy composition. In the case of A413 alloy, eutectic undercooling was only observed in the non-modified base alloy. In the case of alloys modified with Sr, the presence of Sr neutralizes the effect of RE on the freezing range due to its reaction with RE. Addition of La up to 1.5% has no significant effect on the increase in either Tα2 or Te2 compared to that caused by the addition of the same amount of Ce. The increase in the freezing range with the addition of RE metals leads to the formation of a marked amount of shrinkage porosity, in particular in modified alloys. Due to the high affinity of Sr for oxidation, the porosity observed in Sr-modified alloys is twice as much as that in the non-modified alloys, on account of the porosity resulting from the presence of SrO films, in addition to that from shrinkage porosity resulting from the RE metal addition. The main RE-based intermetallics are: Al–RE–Ti, Al–RE–Si, Al–RE–TR–Si (TR = transition metals). In high Si-containing alloy, i.e., 413 alloy, Al–Re–Si compound was frequently observed.

Biocomposites are increasingly being applied in the automotive industry. For assembly purpose, drilling process is often performed in these biocomposites parts to produce holes. The machining behavior of biocomposites is affected by the matrix, the reinforcements (nature and size), by the cutting conditions and the mechanical properties of biocomposites. Some of the newly developed biocomposites are made of a polypropylene/polyolefin blend matrix, which has low thermal conductivity and low softening temperature. Therefore, the selection of cutting parameters should be done with care to avoid thermal-induced damages occurred during drilling biocomposites. Also, due to the heterogeneous and anisotropic properties of biocomposites, it is essential to develop models for predicting the effects of these factors on the machining process performance indicators. In this research work, a full factorial design is used to investigate the effects of machining parameters (feed rate, drill diameter, spindle speed, and reinforcement type) on machinability indicators during the drilling of the three new biocomposites: Polypropylene/Polyolefin matrix reinforced with biocarbon particles and/or miscanthus fibers. The regression and ANFIS-based models are established for predicting thrust force (Ft) and surface roughness (Ra) based on empirical data. The results obtained show that, for each tested biocomposite, the proposed ANFIS models have better predictive accuracy for thrust force and surface roughness than the regression-based models. Furthermore, the drilling parameters and reinforcements used in these biocomposites considerably affect their machinability.

Referring to extensive use of aluminum alloy (AA) 6061 in various types of industrial divisions, adequate knowledge of factors governing machinability aspects of AA 6061 under different heat treatment conditions (T6, T4, and T651) is important. This subject has received limited attention in the literature. Therefore, surface roughness, cutting force, tool wear as well as burr formation morphology, and chip shape were considered as the main machinability attributes during dry drilling tests. Under specific conditions, the bio-lubricant was used, and the obtained results were compared with those recorded under dry condition. Although heat treatment conditions may increase the hardness of the work parts, consequently higher cutting force and more built up edge were observed under dry condition. Although better machinability was observed under lubricated tests, however, due to interaction effects between cutting parameters, an adequate selection of cutting tool material and geometry as well as lubrication strategy and flow rate are of prime choice in order to improve the machinability of heat treated work parts.

The main objective of this review is to analyze the equations proposed for expressing the effect of various parameters on porosity formation in aluminum-based alloys. These parameters include alloying elements, solidification rate, grain refining, modification, hydrogen content, as well as the applied pressure on porosity formation in such alloys. They are used to establish as precisely as possible a statistical model to describe the resulting porosity characteristics such as the percentage porosity and pore characteristics, as controlled by the chemical composition of the alloy, modification, grain refining, and the casting conditions. The measured parameters of percentage porosity, maximum pore area, average pore area, maximum pore length, and average pore length, which were obtained from statistical analysis, are discussed, and they are supported using optical micrographs, electron microscopic images of fractured tensile bars, as well as radiography. In addition, an analysis of the statistical data is presented. It should be noted that all alloys described were well degassed and filtered prior to casting.

Particles emitted during manufacturing processes such as polishing can represent a serious danger for the environment and for occupational safety. The formation mechanisms responsible for these dust emissions include chip formation, friction at the tool/workpiece and chip/tool interfaces, shearing and cutting. These mechanisms thus depend on workpiece and tool properties, as well as the polishing conditions. In the case of granite polishing, particle emissions during polishing can contain chemical compounds such as silica, which represent harmful health risks for the worker. It is therefore important to characterize the particles emitted and to search for possible interactions between the particles (size and composition) and the machining conditions in order to find ways of reducing emissions at the source. In this study, an investigation was undertaken to characterize the particles emitted during granite polishing as a function of polishing conditions, type of granite, and abrasive grit sizes used. Scanning electron microscopy (SEM) was employed for particle morphology characterization and particle grain size and chemical composition were evaluated using X-ray diffraction (XRD) and energy dispersive X-ray (EDX) techniques, respectively. Results show that the influence of polishing speed and feed rate on particle emission depends mainly on the granite type used, providing useful information for controlling the polishing procedure, and thereby dust emission.

In this research, an experimental investigation was carried out to investigate the interaction between various turning parameters and different Minimum Quantity Lubrication (MQL) flow rates and compare their effects on chip shape and surface integrity characteristics in low speed turning and high speed turning of AA6061-T6. The turning parameters included cutting speed, feed rate, and depth of cut. The flow rates comprised 3.5, 10, and 15 ml/min, and the surface integrity characteristics consisted of average arithmetic surface roughness, height peak from the valley, axial and hoop surface residual stresses. The results showed that cutting conditions including cutting speed, feed rate, and depth of cut affected chip shape, while MQL flow rate had no impact on chip shape. The lowest values of cutting speed, feed rate, and depth of cut, equal to 145 m/min, 0.07 mm/rev, and 0.66 mm, respectively, resulted in the smallest residual stresses for all the flow rates. Moreover, the smallest surface roughness parameters were obtained at the lowest feed rate (0.07 mm/rev) for all the flow rates, whereas there were high interaction effects between cutting speed and flow rate and depth of cut and flow rate. Finally, turning with the minimum quantity lubrications of 3.5 and 10 ml/min, respectively, are suggested to obtain the best overall surface integrity characteristics. These lower values of flow rate are suitable to reduce machining costs, protect the environment, and preserve machinist’s health. Since most of the previous research studies focused on the comparison of the turning environments including dry, MQL, wet, and cryogenic and only a few research works on the comparative analysis of MQL turning with different flow rates were carried out, the results of the present research can be utilized as a reference for future works in this field.

In the manufacturing industry, cutting tool failure is a serious event which causes damage to the cutting tool and reduces the quality of the product, which increases the cost of production. A reliable, intelligent, tool wear monitoring system is required in the metal cutting manufacturing process to mitigate these negative effects. This study presents a model-based approach for tool wear monitoring based on an adaptive neuro-fuzzy inference system (ANFIS) for a cold-finished steel bar 1215 turning process. A three-input cutting force (Fx, Fy and Fz) and single-output (tool flank wear) model was designed and implemented using the ANFIS approach. The forces were measured using a piezoelectric dynamometer and data acquisition system. Flank wear was also monitored using a tool maker’s microscope. The model prediction results show that it is accurate enough to perform online monitoring of the turning process and can detect wear while operating.

New biocomposites are increasingly being developed and applied in engineering and manufacturing. The reinforcement type used in biocomposite is one of the major factors that greatly affect the machinability of biocomposite. This study investigated the drilling of two biocomposites (polypropylene-based biocomposite reinforced with biocarbon M1 (30 wt% biocarbon + PP/POE/MAPP) and chopped miscanthus fibers M2 (30 wt% miscanthus + PP/POE/MAPP)). A full factorial design was used for this study. The effects of drilling parameters and reinforcement types on surface roughness, thrust force, specific cutting energy, fine particles, and ultrafine particle generation were measured and analyzed. The results show that the thrust force and specific cutting energy during drilling of biocomposite M1 is bigger than that of biocomposite M2 under the same cutting conditions. However, the surface roughness and fine dust emitted when drilling biocomposite M1 are smaller than those from biocomposite M2, respectively. The reinforcement types of biocomposite, cutting parameters and drill diameter greatly affected fine particles emission. Meanwhile, the cutting conditions are not statistically significant for ultrafine particle generation during dry drilling of both biocomposites.

The present research investigates the effect of turning environments and parameters on surface integrity induced by turning of AA6061-T6. Specifically, the evolution of turning parameters of cutting speed, feed rate, and depth of cut was studied under dry, minimum quantity lubrication (MQL), and wet environments and their impact on surface roughness and residual stresses, as critical parameters for surface integrity, were quantified. Machining tests were carried out using a design of experiment (DoE) based on central composite design (CCD) under the three turning environments. The most effective turning parameters were identified for each environment using analysis of variance (ANOVA). Response surface method (RSM) was used to predict effective regression models for each turning environment for the average arithmetic surface roughness, the height peak from the valley, the axial surface residual stress, and the hoop surface residual stress. Then, using the predictive regression models, a multi-objective optimization study was performed to determine optimal turning parameters in each environment for improved surface integrity in low speed turning (LST) and high speed turning (HST) of AA6061-T6. The results showed that feed rate and cutting speed were the most effective parameters on surface integrity. It was also found that better surface integrity and higher material removal rate (MRR) were achieved using MQL mode, which is an environmental friendly and cost-saving turning environment.

The aluminium alloy 7050-T7451 is generally considered as the principal choice in aeronautical applications demanding adequate strength, stress corrosion cracking resistance, and toughness. Surprisingly, despite extensive research works on machining and machinability of aluminium alloys, including aluminium alloy 7075-T6, limited information was found on machining and machinability evaluation of 7050-T7451, which belongs to a similar family as 7075-T6. To remedy the lack of knowledge determined, dry ball-end milling operations were performed with coated end milling tools on both materials. Experimental characterization and cutting force measurements were performed to measure/evaluate the cutting forces, burr formation morphology, insert performance (wear/breakage), and surface quality attributes. According to experimental studies, 7050-T7451 was found more machinable than 7075-T6. Less burr formation and better surface quality were observed on 7075-T6. Machining attributes are influenced by different experimental factors. However, other machinability attributes, including residual stress, vibration modes, as well as particle emission, must be studied under various lubrication modes and machining operations in subsequent studies. This also recalls further studies on simultaneous multiple response optimization.

In this study, the effects of cutting speed, feed rate, and hardness of workpiece material on the particle number concentration ultrafine of particles in the face milling were experimentally investigated. AISI 1045 steel was hardened to 17, 38, and 48 HRC, machining using ceramic insert (honed, T-land edge preparation). Three factors (cutting speed, feed rate, and workpiece hardness) and three levels fractional experiment designs completed (L27) with statistical analysis of variance (ANOVA) were performed. The analysis of the results shows that workpiece hardness has the greatest influence on ultrafine particle (UFP) emission for both tools and that the feed rate and the cutting speed should be selected wisely for each tool edge preparation. Overall, it is shown that the use of honed edge at moderate speed and higher feed rate reduces UFP emission during milling.

Under certain conditions, dry machining has been known to offer improved efficiency. To determine the effectiveness of dry machining in the production of steel, it is necessary to identify optimal ...

Die-sinking electrical discharge machining (EDM) is the principal method used to machine critical components made of Al6061 alloy for space applications. Geometrical precision and surface roughness are among the most important acceptance criteria for these machined parts. The purpose of this research work is to identify the most significant parameters affecting the material removal rate (MRR), the electrode radius wear rate (EWR), and the surface roughness (Sa) when machining Al6061-T6 aluminum alloy by die-sinking electrical discharge machining and to use this knowledge in future work to generate accurate predictive models. To this end, ten universal machining parameters were selected, and using a Plackett–Burman Design of Experiments (DOE) approach, their influence and relative impact on MRR, EWR, and Sa were calculated and validated using experiments. A comprehensive Analysis of Variance (ANOVA) was then conducted based on the obtained results. It was found that the discharge current, the discharge duration, and the system voltage significantly affect the MRR, while these same three parameters plus the delay between two series of discharges significantly affect the EWR. The surface roughness was affected by the discharge current, the discharge duration, the voltage, the delay between two discharges, and the delay between two series of discharges. The obtained results were analyzed in terms of the relationship between energy input during machining and the surface modification of the material.

The present study was conducted on the machinability of 396 alloy (containing approximately 11% Si) and B319.2 alloy mainly to emphasize the effects of Fe-intermetallics, i.e., α-Fe, β-Fe, and sludge. The results demonstrate that the presence of sludge in the form of hard spots has a significant effect on cutting forces and tool life, in that it decreases drill life by 50% compared to the base alloy. The formation of the α-Fe phase in the M1 base alloy has a beneficial effect on tool life in that this alloy produces the highest number of holes drilled compared to alloys containing sludge or β-Fe; this result may be explained by the fact that the formation of the α-Fe intermetallic, with its rounded Chinese script morphology and its presence within α-Al dendrites, is expected to improve matrix homogeneity via hardening of the soft α-Al dendrites. Increasing the Fe-content from 0.5% to 1% in the 396-T6 alloy containing 0.5% Mn produces a distinct improvement in alloy machinability in terms of cutting force and tool life. The addition of Fe and/or Mn appears to have no discernible effect on the build-up edge area (BUE) and chip shape.

This study was undertaken to emphasize the influence of Sn and Bi addition on the machinability of Sr-modified, grain-refined, and heat-treated Al–Si B319 and 396 alloys. Drilling and tapping tests were conducted to examine the cutting forces, tool life, tool wear, built-up edge evolution, and chip shape. Microstructures were examined using optical and electron microscopy. Drilling test results show that the B319.2 alloy with 0.15%Sn yields the longest drill life, i.e., twice that of the B319.2 alloy containing 0.5%Bi, and one-and-a-half times that of the B319.2 alloy containing 0.15%Sn + 0.5%Bi. The presence of 0.5%Bi in the B319.2 alloy causes a deterioration of drill life (cf., 1101 holes with 2100 holes drilled in the B319.2 alloy containing 0.15%Sn). The α-Fe phase in the 396 alloy produces the highest number of holes drilled compared with alloys containing sludge or β-Fe. The presence of sludge decreases the drill life by 50%. Built-up edge (BUE) measurements and optical photographs show little change in the BUE width for different numbers of holes except for the B319.2 alloy containing 0.5%Bi, which shows a slightly lower width (0.166 mm) compared with that containing 0.15% Sn (0.184 mm) or 0.15%Sn + 0.5%Bi (0.170 mm).

The present work was performed on three versions of a newly developed alloy coded T200 containing 6.5% Cu, 0.1% Fe, 0.45% Mg, and 0.18% Zr in addition to A319 and A356 alloys (grain refined and Sr-modified). Tensile bars were subjected to 13 different heat treatments prior to testing at either 25 °C or 250 °C. The tensile data were analyzed using the quality index method. The results obtained showed that, due to the high copper content in the T200 alloy coupled with proper grain refining, the alloy possesses the highest quality as well as improved resistance to softening when tested at 250 °C among the five alloys. The results also demonstrate the best heat treatment condition to maximize the use of the T200 alloy for automotive applications. Grain-refined alloy B, treated in the T6 temper and tested at 250 °C, exhibited the best combination of the four tensile parameters, i.e., UTS, YS, %El, and Q-values: 308 MPa, 304 MPa, 2.3%, and 352 MPa, respectively, which are comparable with those obtained from the 356 alloy: 309 MPa, 305 MPa, 2.8%, and 375 MPa in the same order.

Aerosol transport is a fundamental phenomenon in many environmental and industrial applications. The study of the dispersion of aerosols, such as contaminants, in the workplace and the search for solutions to capture them are the biggest challenges currently faced in the field of occupational safety and health. In addition, laws and regulations that limit the level of worker exposure to contaminants in workplaces are becoming stricter. The aim of this study was to help reduce exposure to dust, including crystalline silica dust, emitted during the granite polishing process. During this process, the ultrafine particles generated are more difficult to capture than the fine ones, especially in rotational polishing, which causes the worst cases of dust exposure. An experimental test bench was set up to simulate ultrafine particle dispersion and assess three solutions for reducing worker exposure during the rotational polishing process. The use of the test bench allowed experiments to be performed while avoiding human exposure. Results showed that the test bench efficiently simulated the dispersion of ultrafine particle dust. Three solutions designed to reduce dust emissions, based on local exhaust ventilation, were evaluated on the test bench: a push–pull system, a dust shroud and a tool with integrated suction slots. They proved to be more than 95% effective. The results of this work highlight that the performance of local exhaust ventilation systems is very sensitive to the suction flowrate and the speed of the rotating disc, thus illustrating the complexity of dust removal associated with polishing processes in industrial environments.

This article presents the influence of machining conditions on typical process performance indicators, namely cutting force, specific cutting energy, cutting temperature, tool wear, and fine dust emission during dry milling of CFRPs. The main goal is to determine the machining process window for obtaining quality parts with acceptable tool performance and limited dust emission. For achieving this, the cutting temperature was examined using analytical and empirical models, and systematic cutting experiments were conducted to assess the reliability of the theoretical predictions. A full factorial design was used for the experimental design. The experiments were conducted on a CNC milling machine with cutting speeds of 10,000, 15,000, and 20,000 rpm and feed rates of 2, 4, and 6 µm/tooth. Based on the results, it was ascertained that spindle speed significantly affects the cutting temperature and fine particle emission while cutting force, specific cutting energy, and tool wear are influenced by the feed rate. The optimal conditions for cutting force and tool wear were observed at a cutting speed of 10,000 rpm. The cutting temperature did not exceed the glass transition temperature for the cutting speeds tested and feed rates used. The fine particles emitted ranged from 0.5 to 10 µm aerodynamic diameters with a maximum concentration of 2776.6 particles for those of 0.5 µm diameters. Finally, results of the experimental optimization are presented, and the model is validated. The results obtained may be used to better understand specific phenomena associated with the milling of CFRPs and provide the means to select effective milling parameters to improve the technology and economics of the process.

The Al-B4C metal matrix composite (MMC) is characterized by its ability to absorb neutrons which makes it the most suitable shielding material for nuclear reactors. The present work was performed on two series of Al-B4C metal matrix composites made using a powder injection apparatus. In one series, commercially pure aluminum (A5) served as the matrix. For the second set, 6063 alloy was used. In all cases the volume fraction of B4C reinforcement particles (grit size 400 mesh, purity 99.5%) was approximately 15%. The volume fraction of the injected B4C particles was determined using a computer driven image analyzer. Measured amounts of Ti, Zr, and Ti + Zr, were added to the molten composites of both series. Microstructural characterization was carried out employing a field emission scanning electron microscope operating at 20 kV and equipped with an electron dispersive x-ray spectroscopic system (EDS). The same technique was applied to characterize the fracture behavior of the tested composites. Mechanical properties of these composites were investigated using impact testing, and ambient and high temperature tensile testing methods. Almost 1000 impact and tensile samples were tested following different heat treatments. The obtained results from these investigations are reported in this Chapter.

This paper presents a numerical investigation of the effects of chamfered and sharp cemented carbide tools using finite element method-based DEFORM-2D software and cutting parameters on different machining characteristics during the orthogonal cutting of AISI 1045 steel. The objective is to study the interactions between chamfer width, chamfer angle, sharp angle and the cutting speed and feed rate on the cutting temperature, effective stress and wear depth. These effects were investigated statistically using the analysis of variance (ANOVA) test. The obtained numerical results showed that for the chamfer tool, high values of temperature, stress and wear depth were obtained for chamfer widths of 0.35 mm and 0.45 mm. In terms of combined influences, for the cutting temperature and stress, a strong interaction between the cutting speed and chamfer width was obtained. For the sharp tool design, and in terms of temperature, strong interactions are mostly observed between cutting speeds and feed rates. The ANOVA showed that for both chamfer and sharp tools, the feed rate, the cutting speed and their interactions are the most significant parameters that influence temperature and stress.

The effect of tramp elements, mainly Bi and Ca, on the thermal characteristics of Sr-modified Al–Si–Cu and Al–Si–Cu–Mg alloys has been investigated using thermal analysis, X-ray radiography, and field emission scanning electron microscopy (FESEM) techniques. The high affinity of Bi to interact with Sr results in an increase in the Al-Si eutectic temperature, and hence an increase in the size of eutectic silicon particles. In contrast, the Ca–Sr interaction seems to have no significant effect on the alloy thermal behavior. The effect of these interactions on porosity formation has been discussed. Hot zones may be formed in thin cavities, in particular, near the bottom of the mold, leading to formation of unexpected coarse porosity, mostly shrinkage type. The study also highlights the significance of other parameters on porosity formation, such as no melt degassing, SrO, Al2O3 (strings or bifilms), as well as the presence of iron-based intermetallics.

The present research work aimed to study the effects of cutting environments and conditions on tool wear and residual stresses induced by orthogonal cutting of AA6061-T6. Cutting environments included dry- and flood-coolant modes and cutting conditions consisted of cutting speed and feed rate. A 2D finite element (FE) model was developed to predict tool wear and residual stresses and was validated by experimental measurements including machining forces, tool wear, and residual stresses. This was obtained by exploring various magnitudes of the shear friction factor and heat transfer coefficient and choosing proper coefficients using the calibration of the predicted results with the measured ones. The experimental results showed that the effect of cutting environment including dry and flood-coolant modes was negligible on machining forces. The experimental investigation also demonstrated that increasing feed rate raised machining forces, tool wear and residual stresses in both cutting environments. Low Speed Cutting (LSC) led to the highest value of tool wear and High Speed Cutting (HSC) provided the lowest values of resultant machining forces and residual stresses in both modes. Flood-coolant mode reduced tool wear and slightly decreased tensile residual stresses in comparison with dry mode. As a result, low feed rate and high-speed cutting under flood-coolant mode were proposed in order to improve tool wear and residual stress in orthogonal cutting of AA6061-T6.

The aim of this article is to understand the surface quality, as well as the emission and dispersion of dust particles generated during dry polishing of granite, with a view to minimizing both surface roughness and dust particles emission by optimizing the parameters of the industrial process. The optimized polishing parameters found must have a good influence on both the surface quality and the dust particles emission. Investigating dust particle dispersion will help with the design of ventilation solutions to capture dust during the polishing process. Results show that the spindle speed and the feed rate of the polishing tool have important influence on the surface quality and the dust particles emission during the dry polishing process. Choosing a spindle speed of approximately 1500 rpm and an average feed rate of 17 mm/s to perform the dry polishing of granite is a good compromise, which leads to minimize dust particles emission while achieving a good surface finish. It is also shown that the dust emitted contaminates in the same way the vicinity and near the polishing tool. The dust particles, emitted during dry polishing of granite, belong to PM2.5 (particles less than 2.5 μm in diameter). These particles, once inhaled, easily reach the lung alveolar region and cause serious injuries.

Today’s metal matrix composites are widely used due to their excellent properties, which are useful for high-performance applications in the automotive and aerospace industries. Furthermore, improving the machinability of these composites is vital for improving product quality in the manufacturing process. In this research, various adaptive network-based fuzzy inference systems (ANFISs) were introduced to evaluate the effect of the feed rate, the cutting speed and the particle size on the machinability of Al–20 Mg2Si metal matrix composite. Two ANFIS models were selected as the most precise models for predicting surface roughness and cutting force. Results show that the proposed ANFIS models have an adequate accuracy in predicting the machinability of metal matrix composites.

Titanium metal matrix composite (Ti-MMC) has excellent features and capabilities which can be considered a potential candidate to replace commercial titanium and superalloys within an extensive range of products and industrial sectors. Regardless of the superior features in Ti-MMC, however, referring to several factors including high unit cost and existence of rigid and abrasive ceramic particles in the generated matrices of the work part, the Ti-MMC is grouped as extremely difficult to cut with a poor level of machinability. Furthermore, adequate process parameters for machining Ti-MMCs under several lubrication methods are rarely studied. Therefore, adequate knowledge of this regard is strongly demanded. Among machinability attributes, ultrafine particles (UFPs) and fine particles (FPs) have been selected as the main machinability attributes and the factors leading to minimized emission have been studied. According to experimental observations, despite the type of coating used, the use of higher levels of flow rate led to less UFPs, while no significant effects were observed on UFPs. Under similar cutting conditions, higher levels of FPs were recorded under the use of uncoated inserts. Moreover, cutting speed had no significant influence on UFPs; nevertheless, it significantly affects the FPs despite the type of insert used.

Machining burrs are formed at all machined workpiece edges. One useful solution to decrease machining time and cost, in particular for milling parts, is to generate machined parts edges with minimum burr. This article proposes burr edge occupancy ηs as an index to evaluate deburring difficulty and, consequently, adequate selection of suitable deburring methods. Initially the sensitivity of ηs to cutting parameters must be evaluated. We investigated the main governing factors on ηs when slot milling two types of aluminium alloys (from different families) that are used in the automotive and aerospace industries. The cutting parameters that led to edges with minimum ηs are presented. It was found that, unlike most burr size attributes, ηs is sensitive to variation of the cutting parameters used: cutting speed, family of material, and cutting tools. Lower ηs means less time and effort for deburring and edge finishing of machined parts. Furthermore, ηs measurement is more convenient than the procedures used to measure other burr size attributes, including burr height (bh) and burr thickness (bt).

Hard turning technology was proven effective in enhancing the surface finish and dimensional accuracy of hardened steel. For this reason, it is used for finishing operations in the manufacturing of some critical aircraft landing gear components where bulk material hardness exceeds 45 HRC such as 300M ultra-high-strength steel. Nonetheless, the selection of cutting conditions remains critical to ensure generated surface characteristics meet the performance requirements. In this context, this study focuses on the optimization of hard turning cutting conditions to reduce surface roughness, increase compressive surface residual stresses, and reduce surface white layer thickness of 300M ultra-high-strength steel (55 HRC). To this end, a design of experiments (DoE) is used to investigate the effects of cutting tool (T), cutting speed (V), feed rate (f), and depth of cut (D) during hard turning. The cutting tool materials investigated include physical vapor deposited AlTiN–coated cemented carbide, mixed ceramic, and polycrystalline cubic boron nitride (PCBN), all commonly used in hard turning. Three different optimization approaches are evaluated and compared, namely the single-response Taguchi method, the multi-response grey relational analysis (GRA), and the proportion quality loss reduction (PQLR) methodologies. Because responses were found to be correlated, the selected multi-response optimization approaches were combined with the principal component analysis (PCA) method to transform correlated parameters into uncorrelated ones. The effect of cutting parameters and their interactions on surface roughness (Ra) and white layer thickness (WL) were considered in detail, particularly the effect of cutting tool material. Results demonstrate that the PCA-based GRA approach is a very suitable optimization technique for hard turning of 300M steel. Under those optimized conditions, Ra was decreased by 50%, and WL was decreased by 6% while compressive axial surface residual stress (ASRS) and hoop surface residual stress (HSRS) were increased by 307% and 74%, respectively.

An original approach is introduced to discriminate the effects of residual stress and surface roughness on turned Inconel 718 alloy parts. This could be used for assessing or studying the performance of these specimens during fatigue tests. This method consists of building surface integrity maps in terms of surface roughness parameters and residual stress in order to select specific turning conditions with adequate machining parameters. The surface integrity maps were generated by using response surface methodology based empirical models and precision turning tests on coupons. The proposed approach was therefore successfully applied to manufacture rotating bending fatigue specimens with the surface axial residual stress varying from − 239 to 446 MPa while keeping the arithmetic average roughness and the surface hoop residual stress constant. The effect of the surface axial residual stress on the fatigue life could thus be discriminated from the other surface integrity characteristics effects. The proposed methodology is independent of the manufacturing process and can be extended to other machining processes such as milling, grinding, and broaching.

The granite manufacturing industry is an environment in which workers are exposed to high levels of ultrafine particles (UFPs) and crystalline silica dust. Overexposure to crystalline silica can cause health problems, in particular silicosis. This fatal lung disease persists worldwide despite knowledge of methods to control it. One way to partially overcome the problem of subjectivity and try to achieve objective experimental results is to run field crystalline silica dust surveys with trained human assessors (panelists). Such field inspections allow the determination of ambient air concentrations and are now seen as being a more convenient method for UFP impact assessment in the field. One drawback of field inspections is that they can get rather expensive, especially if the survey is conducted for an extended period of time involving a high number of panelists. This paper reviews the techniques that can be adopted to measure UFPs in the field and discusses how such techniques can be used as an alternative to, or in combination with, gas tracer dispersion methods for UFP impact assessment purposes, and how the results of field UFP measurements and model outputs can be related and compared to each other. Two simulation methods were used to study crystalline silica dust exposure during the granite polishing process (experimental and numerical). This study presents a method to measure UFP dispersion during granite manufacturing processes. A computational model was constructed to simulate the physical problem. The numerical study was carried out, on a simplified configuration (bench), modeling particle distribution near a rotating tool. CFD simulation results were compared to the experimental data using NaCl particles, a tracer gas (CO2), and UFP dispersion from granite polishing. The results showed good agreement between the two methods.

The present work investigated the effect of aging treatment on the microstructure and tensile properties of an Al-2%Cu base alloy containing various additions of Zr and other alloying elements. Aging was carried out at temperatures of 180–300 °C for different aging times at each temperature. The tensile properties indicated that Zr additions improved the strength of the base alloy, especially at high Zr levels at 180 °C. At the 220 °C aging temperature, however, while Zr addition did not have a beneficial effect on the alloy strength, the ductility was found to improve. Zr-Ti combined additions had a significant effect on the microstructure of the base alloy, as the morphology of the α-Al grains transformed into a non-dendritic morphology, and the grain size decreased sharply. These effects were at their maximum at 180 °C and 0.5 wt% Zr addition. Moreover, the Zr-containing alloys aged at higher temperatures, such as 220 °C and 240 °C, maintained a noticeably higher level of strength over the base alloy aged at the same temperatures. Quality index charts based on the tensile test data also reflected an improvement in alloy quality and strength with Zr-Ti combined additions.

The present article reviews a large number of research publications on the effect of mischmetal (MM), rare earth metals (RE), La or Ce, and combinations of La + Ce on the performance of Al-Si cast alloys mainly 319, 356, 380, 413, and 390 alloys. Most of these articles focused on the use of rare earth metals as a substitute for strontium (Sr) as a eutectic silicon (Si) modifier if added in low percentage (< 1 wt.%) to avoid precipitation of a significant amount of insoluble intermetallics and hence poor mechanical properties. Other points that were considered were the affinity of RE to react with Sr., reducing its effectiveness as modifier, as well as the grain refining efficiency of the added RE in any form. None of these articles mentioned the exact composition of the RE used and percentage of tramp elements inherited from the parent ore. Using high purity La or Ce proved to have no effect on the Si shape, size or distribution, in particular at low solidification rates (thick sections). However, regardless the source of the RE, its addition to Sr-modified alloys reduced the modification effect. As for grain refining, apparently a high percentage of RE (> 1 wt.%) is required to achieve a noticeable reduction in grain size, however at the cost of alloy brittleness.