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Purpose Parts created with fused deposition modelling (FDM) have poor surface quality and dimensional accuracy, which limits their applicability in a variety of applications. Therefore, post process of FDM parts seems to be essential to tackle these problems. The purpose of this study is to study the influence of lapping parameters (time, weight and angular velocity) on the surface roughness, material removal rate (MRR) and flexural strength of acrylonitrile butadiene styrene (ABS) parts manufactured by FDM were post processed with the aid of lapping operation. Design/methodology/approach After printing the specimens, parts were lapped according to the Taguchi design of experiments. The surface roughness of the lapped parts was then evaluated by using laser profilometry, and the results were compared to study how lapping parameters affected surface roughness. A digital microscope was used to examine the surface damage of components that were being lapped. After that, the flexural strength of lapped parts was compared with the untreated part to study the effect of lapping process on the flexural strength. Finally, the influence of lapping parameters was investigated on the thickness change and MRR. Findings The results showed that while by increasing lapping time the surface roughness would improve; angular velocity and weight have an optimal value. The results also illustrated that not only the surface roughness of all ABS samples improve significantly but also the antistrophic behaviour of additively manufactured parts is turned to isotropic behaviour without decreasing flexural strength of specimens. MRR is also proportional to these parameters and by rising the value of them, MRR will increase. Originality/value The previous techniques of improving surface roughness whether chemical treatment or mechanical treatment had some disadvantages such as reducing mechanical properties, cost, long time of the process and so forth. As a result, finding a new approach such as lapping process to overcome the problems of previous methods seems to be necessary.

Purpose The purpose of this paper is to investigate the variables of the fused deposition modelling (FDM) process and improve their effect on the mechanical properties of acrylonitrile butadiene styrene (ABS) components reinforced with copper microparticles. Design/methodology/approach In the experimental approach, after drying the ABS granule, it was mixed with copper microparticles (at concentrations of 5%, 8% and 10%) in a single screw extruder to fabricate pure ABS and composite filaments. Then, by making the components by the FDM process, the tensile strength of the parts was determined through tensile strength tests. Taguchi DOE method was used to design the experiments in which nozzle temperature, filling pattern and layer thickness were the design variables. The analysis of variance (ANOVA) and signal-to-noise analysis were conducted to determine the effectiveness of each FDM process parameter on the ultimate tensile strength of printed samples. Following that, the main effect analysis was used to optimize each process parameter for pure ABS and its composite at different copper contents. Findings The study allows the layer thickness and filling pattern had the highest effects on the ultimate tensile strength of the printed materials (pure and composite) in the FDM process. Moreover, the results show that the ultimate tensile strength of the ABS composite containing 5% copper was nearly 12.3% higher than the pure ABS part. According to validation tests, the maximum error of experiments was about 0.96%. Originality/value In this paper, the effect of copper microparticles (as filling agent) was investigated on the ultimate tensile strength of printed ABS material during the FDM process.

The quest for precision in manufacturing sector is continuously evolving with the introduction of modern technologies and new techniques. In this research, the characteristics and influential parameters of a recently developed polishing process, known as electrophoretic deposition-assisted polishing (EPDAP), were investigated in external surface polishing of AISI 316 L stainless steel. The results revealed the improvement of surface roughness with increasing axial load up to the certain value of 11 N. The polishing time between 6 min and 12 min was recommended for polishing surfaces having a moderate initial roughness, close to 0.1 µm. Moreover, the increase of tool rotational speed led to the improvement of surface quality, while the variation of applied voltage had insignificant effects on the surface texture. In the second series of experiments, predictive equations of average surface roughness and material removal rate (MRR) were obtained based on analysis of variance. It was concluded that axial load and tool rotational speed are the most influential parameters on surface roughness and MRR, respectively. By performing a multi-response optimization, the optimum levels of control parameters at the same voltage of 15 V were calculated as axial load of 12 N, polishing time of 10 min, and tool rotational speed of 2000 rpm. This combination reduced the average surface roughness by 54.17% relative to the worst condition, which is characterized by the lowest axial loads, rotational speed, and polishing time at the design space. The maximum MRR of 3.975 mg/min was achieved at this optimum point. Assessment of the surface features indicated that the EPDAP process created uniform roughness profiles and resulted in an enhanced surface reflectance.

This paper presents the analytical and experimental investigations on different factors such as surface integrity, flexural strength and grinding energy and cost of Alumina through the use of various diamond grinding wheels. For obtaining the analytical model for single-grit grinding, the effect of strain rate and grinding temperature are also included in the formulation. Moreover, the experimental tests are conducted with four different diamond grinding wheels to grind Alumina blocks. The applied force during grinding is measured. Then, the other important parameters, including surface roughness, wheel wear, and grinding cost are analyzed. According to the obtained results, a good agreement between the experimental and analytical results were achieved in all cases. Furthermore, it was found that controlling the grinding condition would be resulted in 11% reduction in the subsurface damages (SSD) according to the images of Scanning electron microscope (SEM) results at the distance of 150 μm under the ground surface. A converging improvement trend of the surface integrity and flexural strength was also observed. Also, approximately 29% improvement was attained for the flexural strength in optimum condition. In addition, the optimal condition for grinding was determined, in which 66% decrease in surface roughness and 75% decrease in grinding cost were accomplished.

Knowledge of material removal behavior and generated surface characteristics are crucial to improve grinding performance. A finite element model was developed using a single grit approach with the consideration of uncut chip thick variations along the grain path. It was found that the increase in cutting speed and the decrease in rake angle led to the generation of discontinuous chips in adiabatic shearing conditions. Besides, the larger shear stresses induced by friction in the grain-chip interface contributed to the formation of chips with larger discontinuities. The enlargement of subsurface damage (SSD) depth by 23.86% and 129.42% was caused by the increase in grain edge radius from 0.5 to 2.5 μm and the rise in maximum uncut chip thickness from 0.5 to 1.5 μm, respectively. However, the SSD depth firstly decreased, and then increased with the approach to more negative rake angles and larger cutting speeds. A multi-response optimization based on analysis of variance (ANOVA) and SSD predictive model calculated the optimum combination of influential parameters as maximum uncut chip thickness of 0.719 μm, cutting speed of 80 m/s, cutting edge radius of 0.5 μm, and rake angle of − 30°. This led to the minimum SSD depth of 0.406 μm and the maximum removal rate of 57.493 mm3/mm s. The experimental results confirmed the positive contribution of an eco-friendly nanofluid minimum quantity lubrication (NMQL), containing graphene nanoplatelets with 0.3 wt% concentration within the green nanofluid, to the significant improvement of surface roughness (by 41.09%, relative to dry grinding) and morphology.

In the present paper, the impact of grinding on the surface integrity of the PSZ is investigated through analytical, numerical, and experimental studies. The analytical model of the single grit grinding of the PSZ was developed by taking into consideration the strain rate, the grinding temperature, and the phase transformation of the zirconia. Numerical modeling of the grinding-induced SSD and analysis of the relationship between the parameters of this process and crack formation were performed in the ABAQUS Software via coupled finite element – smoothed particle hydrodynamics (FE-SPH) method. The results showed that, in all cases, the experimental data fall within the ranges calculated via the analytical approach. Moreover, the numerical model revealed that, on average, the numerical results differed from the respective experimental data by less than 15%. Investigation of SEM images of the ground surface indicated more than 17% improvement in the surface integrity together with a reduction in the SSD at 100 μm beneath the ground surface from 3.4% down to 0.9%. The ground surface was further studied using X-ray diffraction (XRD) analysis, with the results indicating the correspondence of the trend of the phase transformation from tetragonal to monoclinic to the increasing trend of the surface integrity and bending strength.

Grinding is one of the most complex and accurate machining processes, and the efficiency of the grinding wheel depends significantly on its surface properties. This work aims to propose an algorithmic manner that reduces the cost and time to conduct grinding of an optimized DIN 1.2080 tool steel (SPK) using a soft computing technique to obtain the best combination of input parameters including depth of cut (20, 40, 60 μ m ), wheel speed (15, 20, 25 m / s ), feed rate (100, 300, 500 m m / s ), and incidence angle (0, 30, 45 d e g r e e s ) with respect to output parameters consisting of average surface roughness and specific grinding energy. According to the input parameters and their levels, an experiment using fractional factorial design of experiment (RFDOE) was designed. Later on, two parallel feed-forward backpropagation (FFBPNN) networks with similar topology made up of 4, 11, and 1 units in their input, hidden, and output layers are trained, respectively. After sensitivity analyses of networks for determination of the relative importance of input variables, a genetic algorithm (GA) adopting linear programming (LP) based on Euclidean distance is coupled to networks to seek out the best combinations of input parameters that result in minimum average surface roughness and minimum specific grinding energy. The findings revealed that RFDOE provides valid data for training FFBP networks with a total goodness value of more than 1.99 in both cases. The sensitivity analyses showed that feed rate (38.97%) and incidence angle (33.94%) contribute the most in the case of average surface roughness and specific grinding energy networks, respectively. Despite the similar surface quality based on scanning electron microscopy (SEM), the optimization resulted in an optimized condition of the depth of cut of 25.23 μ m , wheel speed of 15.02 m m / s , feed rate of 369.45 m m / s , and incidence angle of 44.98 d e g r e e s , which had a lower cost value (0.0146) than the optimum one (0.0953). Thus, this study highlights that RFDOE with a hybrid optimization using FFBP networks-GA/LP can effectively minimize both average surface roughness and specific grinding energy of SPK.

Zirconia has been used in medical applications since last few years and an optimum and cost-effective condition in grinding zirconia has drawn industrial attention. This paper aimed to improve and control the surface integrity, flexural strength and grinding cost in grinding partially stabilized zirconia (PSZ) using a diamond grinding wheel. The phase transition and grindability of PSZ were also evaluated. Ground surfaces analysis shows that all samples subjected to the grinding presented an increase in surface integrity, and the subsurface damages 100 below the surface were reduced from 3.4% to 0.9%. The flexural strength using 3 point bending test (3PB) shows that grinding increased the flexural strength more than 29% which is the result of higher surface integrity. The ground surfaces were analyzed using X-ray diffraction (XRD) and the results shows that T-M phase transition trend is in accordance with the surface integrity. In other words, XRD analyses prove that T-M phase transition results in higher flexural strength and surface integrity. It was also observed that in the best condition, the grinding cost was reduced by 72%. It can be concluded that controlling the grinding condition in grinding PSZ will result in the increase of the surface integrity and flexural strength. A mathematical model was created to find an optimum condition using response surface method (RSM). It is observed that feed rate has greater effect on the outputs rather than depth of cut.

The aim of this study is to evaluate the effect of various grinding parameters on the phase transformation, surface roughness, G-ratio, grinding cost, and specific grinding energy of partially stabilized zirconia (PSZ) using different diamond grinding wheels. The use of PSZ ceramic in dental applications has significantly increased in recent years due to excellent mechanical and biological properties. Considering the extreme hardness and brittleness of PSZ besides achieving dimensional and geometrical accuracies, grinding becomes an essential process. PSZ blocks are ground using four different diamond grinding wheels and grinding forces are measured during the grinding process. Next, PSZ phase transformation is analyzed using X-ray diffraction (XRD) and surface roughness; furthermore, wheel wear and grinding cost analysis are performed. All samples subjected to grinding reveal an increase in monoclinic phase content. From the surface integrity point of view, processing the images of scanning electron microscopy (SEM) from the specimens subjected to the grinding with a metal bond diamond grinding wheel shows 12% higher surface integrity. Additionally, it is shown that grinding in an optimum condition could enhance the surface roughness more than 60%. To find this optimum condition as well as to establish a mathematical relationship between inputs and outputs, response surface method (RSM) is employed. The obtained R-square value for the mathematical model is more than 0.90, which confirms the precision of the model.

Nowadays, in addition to technical efficiency, the demands for environmentally-friendly machining processes have increased. In this context, development of an efficient strategy for machining of ceramic matrix composites (CMCs) has found crucial importance. CMCs exhibit outstanding properties, especially under harsh and severe conditions. Machining of CMCs, however, suffers from several disadvantages such as substantial costs, high tool wear, poor surface quality and low material removal rate, highlighting the need for optimization and development of efficient machining strategies. Due to extreme hardness of the ceramic matrix, grinding with diamond abrasives is inevitable. The grinding variables and the coolant-lubricant medium play significant roles in reduction of the energy dissipation and improving the finishing quality. Among coolant-lubricant types, minimum quantity lubrication (MQL) technique, which is known as an inexpensive and environmentally-compatible grinding process, can give the best results. In comparison with dry grinding condition, 37.95% reduction in cutting force, 75.93% reduction in surface roughness, and 150% increase in grinding efficiency have been achieved by MQL method. Considering MQL as the optimum coolant-lubricant medium, four machining strategies were developed using desirability function method in which efficiency, quality, and productivity were studied. Moreover, microstructure analysis and also cutting mechanism of grinding process for different types of fiber orientation have been investigated.

Subsurface damage (SSD) is a predominant type of damage in grinding process of optical materials with direct effect on the optical components performances. A series of cup wheel grinding trials were carried out on optical glass BK7 under different grinding parameters to evaluate their impacts on SSD and surface roughness. The SSD depths of ground specimens were measured by the wedge chemo-mechanical polishing (W-CMP) method. The modified model of Lambropoulos, proposed by Li, was applied considering the ductile regime effect. Besides, a three-dimensional model was established based on the coupled finite element method (FEM) and smoothed particle hydrodynamics (SPH) to simulate the grinding-induced SSD in optical glass BK7. The experimental results were compared with the theoretical model and simulations which showed a good agreement. Therefore, both the theoretical and simulation models could be used for fast and nondestructive evaluation of SSD. Also, a novel method was applied to calculate the crack length of a SEM micrograph through image processing technique.

Grinding is one of the most complex and precise machining operations, with the performance of the grinding wheel being heavily reliant on its surface conditions. Removed chips tend to be forced back to the wheel surface due to the intense heat generated in the grinding zone. The loaded chips block the wheel's grinding capability, resulting in increased grinding force and temperature, wheel chatter, and workpiece thermal degradation. To solve these problems, this research examines the effectiveness of an auxiliary compressed air jet system during the grinding of spk tool steel with an alumina grinding wheel to clean the wheel surface of lodged chips and then the percentage of wheel loading for different tests will also be evaluated. The compressed air nozzle was examined from a variety of perspectives (0, 30, 45, and 60). Grinding with and without a cleaning system, as well as conventional cutting fluid, were also employed as comparisons. In certain output results, input parameters such as grinding wheel speed (20 m/s), cutting depth (20 m), and feed rate (100 mm/s) were maintained constant. When compared to other experiments with different cleaning nozzles, the optimal inclination angle of 45°, which allows the maximum air to reach the interface between the wheel surface and chips, removed chips by pushing them off the wheel surface. Other cleaning nozzles, such as 0°, 30°, and 60°, were less successful. The incidence angle of 45° produced the best results in terms of surface roughness, diametrical grinding wheel wear, G-ratio, tangential forces, specific energy, and wheel loading analysis. Image processing was used to detect and identify chips accumulated between abrasive grains on the wheel surface. To better understand the structure of the wheel and workpiece surface, optical and scanning electron microscopy pictures were taken and analyzed. This research adds to our understanding of the grinding wheel loading mechanism and its dynamics.

Grinding operation is one of the most complex and accurate machining processes whose performance is highly dependent on the surface conditions of the grinding wheel. As the friction between abrasive grains and the workpiece results in a large amount of heat, the use of coolant can prevent the workpiece surface from burning, microstructure alteration, subsurface damages, and hardness variation. To get better the cleaning of the abrasive grains on the surface of the wheel during the grinding process, this paper is focused on the performance of an auxiliary compressed air jet system during grinding of hard-to-grind materials. Moreover, the wheel loading of the grinding wheel will also be evaluated. Different incident angles of the compressed air nozzle (0˚, 30˚, 45˚, and 60˚) were examined. Furthermore, conventional flood coolant, as well as drying with and without a cleaning system, was applied for comparison purposes. Surface roughness, tangential forces, specific energy, wheel loading analysis, and SEM images were evaluated where the incident angle of 45˚ led to the best results. Wheel loading resulted in the accumulation of chips between abrasive grains to the top of cutting grains. Detection and identification of loading has been operated based on image processing technique.

Ceramic matrix composites (CMCs) are a new class of high-technology materials that can be utilized in hot-zone structures and as a lightweight replacement for metallic superalloys. CMCs offer low density, high hardness, and superior thermal and chemical resistance which make them highly attractive in a vast array of applications. Nevertheless, the high hardness, as well as the inhomogeneous structure of the CMCs, causes unstable processes and high tool wear when machining. In this research, MQL grinding, known as an economical and environmentally friendly grinding process, was accomplished and its efficiency was compared with conventional fluid and dry grinding. Along with obtaining of comprehensive results, the effects of main grinding parameters, such as cutting speed, feed speed, and depth of cut, on the grinding forces, specific grinding energy, wheel wear, surface roughness, and integrity were analyzed. The results showed that MQL grinding reduced the grinding forces and specific grinding energy. As a result, wheel wear was lowered and G-ratio was increased. In addition, the surface generated by MQL grinding was smoother than fluid grinding and significantly better than dry grinding.

The performance of Magnetorheological dampers should be analyzed to study the stability of Magnetorheological fluid and its configuration. To this end, in this study a prototype Magnetorheological fluid is presented. The fluid consists of stabilized Silicone dioxide (SiO2) nanoparticles, Stearic acid, Phosphoric acid and micron-sized soft ferromagnetic carbonyl iron particles. To assure the authentic performance, sedimentation and magneto-rheometry tests are conducted. Also, a prototype of double-tube Magnetorheological damper with double magnetic components is fabricated by using the mentioned magnetorheological fluid characteristics. Damping force measurement test is carried out to measure the damping force in various electrical currents. The Kwok model is employed to examine the analytical model predictions against the experiments. Furthermore, a general evolution is presented using the neural network algorithm. It is demonstrated that the damping force in saturated current is almost five times higher than in the zero current. In addition, the derived evolution for the damping force has a high performance to predict the response of the Magnetorheological damper in other electrical currents.

Wheel loading entails chip accumulation in porosities between grains or welding to the top of cutting grains. It is considered one of the most prevalent problems in grinding nickel-based super alloys. Utilizing separate jet cleaning systems can significantly reduce wheel loading. In this study, a separate high-pressure coolant was supplied through a nozzle towards the wheel surface to flush out the chips. The effects of various wheel cleaning parameters on the loaded area to wheel surface ratio in relation to grinding performance were examined. It was observed that the lowest wheel loading was achieved at a nozzle standoff distance of 70 mm from the wheel’s surface. Nozzle stream direction had no significant effect. Increasing flow rate and jet speed led to a significant decrease in wheel loading and corresponding specific energy until a threshold value was reached. Furthermore, the loaded area to wheel surface ratio was reduced by 100 % and the corresponding specific energy by up to 30 % when the wheel cleaning system was employed.

Wheel surface condition plays an important role in the grinding operation. Grinding wheel loading, meaning chip accumulation in the space between grains, leads to deteriorating wheel cutting ability and causes excessive force and temperature. This paper presents an analytical model of wheel loading phenomena as a function of cutting parameters, wheel structure, and material properties. The model is based on the adhesion of workpiece material to abrasive grain surface. It is validated by experimental results from grinding nickel-based superalloy with cubic boron nitride vitrified wheel. This model considers wheel specifications including abrasive grains size and the number of cutting edges. Cutting parameters and process temperature are the other determinant factors. On the basis of this model and empirical results, the effects of the various process parameters are presented.

Grinding performance is evaluated mainly in terms of specific grinding energy. The number of active grits per unit area and their slope is considered as the two grinding wheel topographical key parameters for studying grinding performance. To provide a view on how various parameters influence specific energy and the importance of wheel topography and grit workpiece interaction, a specific grinding energy model is developed. Inputs to this model are workpiece parameters, grinding process parameters, and, in particular, the grinding wheel topographical parameters. This model has been validated by experimental results. The theoretical values considering the complexity of the grinding process reasonably compare with the experimental results. The effect of number of active grits per unit area and their slope on specific grinding energy and then metal removal mechanism is investigated. The results revealed that the number of active grits per unit area has less effect on specific grinding energy than grits slope.

Wheel loading entails chip accumulation in porosities between grains or welding to the top of cutting grains. It is considered one of the most prevalent problems in grinding Nickel-based super alloys. Identification of wheel loading is an important issue for optimizing the dressing intervals, but it can be a time consuming and an expensive process. A novel technique based on digital image processing to determine the loading areas over the surface of CBN vitrified grinding wheels using the toolbox of MATLAB is presented in this paper. The optical characteristics of the metal chips, the abrasive grains and wheel bond are considered. Experiments were performed to examine the repeatability of the proposed technique. The results were verified by the use of a scanning electron microscope. Based on the proposed technique, the effects of cutting parameters on the loaded area to wheel surface ratio in relation to grinding performance were studied empirically.