Investigation of vibratory bed effect on abrasive drag finishing: a DEM study

Purpose The purpose of this paper is to investigate the effect of a vibratory bed, as an assistant agent, on the improvement of the drag finishing process. The dynamics and kinematic of the process were surveyed in microscale for different frequencies and amplitudes and the results were compared to the basic process. Design/methodology/approach The discrete element tool was used to find out the effect of the vibratory bed on the drag finishing process. To this end, the Hertz-Mindlin model was used to investigate the contact of abrasive particles and workpiece. At the first stage, the numerical model was validated with the experimental results, and then the effect of different parameters on the finishing process was evaluated and compared with the basic case. Findings The chosen numerical model was in good agreement with the results measured in the previous literature. Moreover, the results show that not only vibrated bed enhances the contacts of abrasive particles to the workpiece, but it also increases the uniformity of the finished surface. Originality/value In comparison to the experiments, the discrete element technique consumes lower cost and time to estimate the optimum conditions of the finishing process, as well as it provides a good understanding of this phenomenon on the micro-scale.

Professional Mechanical Tooth Cleaning Method for Dental Implant Surface by Agar Particle Blasting

Oral dysfunction due to peri-implantitis and shortened life of implants has become a major concern. Self-care and removal of oral biofilms by professional mechanical tooth cleaning (PMTC) are indispensable for its prevention. However, if the surface roughness of the implant is increased, it may result in the adhesion of biofilm in the oral cavity. Therefore, the PMTC method can serve for long-term implant management. Calcium carbonate (CaCO3) has been used as a cleaning method for implant surfaces; however, there is concern that the implant surface roughness could increase due to particle collision. Therefore, in this study, to establish a blasting cleaning method that does not adversely affect the implant surface, a new blasting cleaning method using agar particles was devised and its practical application examined. When the simulated stains were blasted with white alumina (WA) abrasive grains and CaCO3 particles, the simulated stains were almost removed, the surface roughness changed to a satin-finished surface—which was thought to be due to fine scratches—and the surface roughness increased. Most of the simulated stains were removed on the surface of the sample blasted with glycine particles and agar particles. Conversely, the gloss of the sample surface was maintained after cleaning, and the increase in surface roughness was slight.

Multi-objective optimization of magnetic abrasive finishing by desirability function with genetic algorithm

Thermal stability and Surface hardness of the super-finished surface is a very important aspect to preserve the surface texture of workpiece in the MAF process. In this present study, the multi-objective optimization of EN-31 finished through the MAF process. “Increase in Temperature” and “Increase in Hardness” are considered for optimization to diminish their impact on the super-finished surface of EN-31. In present work Desirability function analysis (DFA) has been used to optimize the desired responses of the MAF process. Experiments were designed according to Taguchi L9 orthogonal array for the finishing of EN-31. The experiment results are processed using DFA and Desirability fitness function is established to convert the single response to multi-response. Genetic Algorithm (GA) is used to enhance the results of DFA and the regression model was developed to obtain the objective function of Genetic algorithm. Smaller-the-best criteria were used for ‘Increase in Temperature’ and ‘Increase in Hardness’ for obtaining favorable process parameters. The best optimal parametric combination is obtained by using the GA-DFA hybrid approach is at 2.5 mm (working gap), 20 gm (abrasive weight), and 2.0 A (Current) and 300 rpm (rotational speed).

Surface integrity in machining of AZ91/SiC composites

Use of metal matrix composites (MMC) is growing due to their high strength-to-weight ratio, resistance to wear, creep, etc. Machining of metal-matrix composites (MMC) faces many challenges, especially with regard to obtaining a finished surface with high quality. In this research, AZ91/SiC samples with different volume fractions are machined at different cutting conditions with respect to feed rate, cutting speed, and depth of cut. Surface integrity of the machined samples is analyzed by different methods such as tactile profilometer and 3D surface topography to investigate the SiC effects on the finished surface. Additionally, sample surfaces are evaluated by scanning electron microscope (SEM) and with energy-dispersive X-ray (EDS) to assess the surface defects formed around reinforcement materials. Results indicate SiC particles decline the surface quality and uniformity due to the formation of some defects such as micro cracks, holes, and undesired deformations when the cutting process. Also, subsurface SiC particles close to the machined surface are cracked after machining.

Multi-factor influence on the roughness of the finished surface

The aim of this work is to develop a novel approach for ensuring the quality of the finished surface based on a multi-factor model. The proposed model can take into account most of the machining process parameters. The main parameters include cutting conditions, dynamic stability of the cutting process, thermal effects in the cutting area. The development of a multi-factor model was based on a literature review and experimental data obtained from the cutting force analysis and colour pyrometry. The data obtained were summarised into a unified multi-factor model. We analysed the key literature sources and summarised the experimental data and findings to assure finished surface quality when controlling one of the input parameters of the machining process. It was shown that the surface quality (roughness) can be achieved by applying different machining parameters. They include the rational cutting conditions, a change in the geo m-etry of a cutting tool, reducing the relative spacial dynamic vibrations of the tool relative to the working surface of the raw part, using the methods influencing the physical and mechanical properties of the processed materials. It was established that the process dynamic stability, the cutting conditions or the chip formation process can be used as an input parameter. The proposed scheme of multi-factor influence of processing parameters on the output parameter - the surface roughness - applies to any materials under processing. The created model takes into account all input parameters of mechanical processing. It aims at the quality management of the finished surface based on the required performance characteristics of the items. Based on the proposed multi-factor scheme, we plan to create an adaptive system capable of controlling the mechanical processing based on a computer numeric control machining centre.

WAVE FORMATION AT THE SUPER-FINISHING DISCS CERAMIC

The phenomenon of wave formation on the super-finished surface of ceramic disks made of ceramic materials with different machinability is considered. The General nature of wave formation during superfinishing and other machining processes (grinding, runningin) due to the loss of stability of the technological system is shown. Reviewed the condition of wave generation, including higher cutting speeds, it is necessary to increase the performance of the super-finishing, and changes sizes of diamond bar height on the buckling and wave generation on the treated surface of the ceramic disk. The influence of the processing time and the interaction force of the bar and the workpiece on the frequency of self-excited vibrations and wave formation is revealed. It has been experimentally established that with a decrease in the workability of ceramics, the rate of increase in the waviness amplitude decreases. Recommendations for reducing the rate of increase in the height of undulation are given.

Development of Resin Fibrous Grinding Wheels Using Twin Nozzle PELID and Analysis of Their Grinding Performance

The development of grinding wheels that are capable of improving the grinding accuracy and the finished surface roughness via the grinding process is increasingly sought in industries. The refinement of grinding wheels comprising abrasive grains is an effective means of improving the ground surface quality. The general methods used for fabricating grinding wheels tend to facilitate the aggregation of fine abrasive grains, resulting in poor abrasive distribution. Therefore, we focused on the electro-spinning mode of Patterning with Electrostatically Injected Droplet (PELID), which is capable of forming micro resin fibers. Subsequently, we attempted to fabricate fibrous grinding wheels containing abrasive grains by using the twin nozzle PELID technique that applies this mode. We confirmed through experiments that resin fibers containing abrasive grains can be manufactured efficiently using PELID and succeeded in manufacturing fibrous grinding wheels containing abrasive grains.

Influence Structures of The Machine Tools on Roughness in Turning

The final quality of machining is directly a function of the type of machine used. The geometrical and micro quality geometrical of finished surface are one of the principal goals of machining. During the operation of turning, in particular, the elastic behaviour of the pin controls the surface quality machined. To say that the rigidity of the machine must be largest possible is not sufficient. The design of the axes of movement of the machine must take account of the effects static, kinematics, dynamic of the mass. The rigidity and the conditions of maintenance by the stages must be qualified in comparison with the results sought in term of machined surface quality. To characterize the effect of the vibrations of the machine tools on the quality of the machined surfaces a study was undertaken on two different lathes, a conventional turn and a turn with numerical control. The results of roughness show that the machine tool exploits a great role the machined surface quality. The rigidity of the machine and its capacities damping are prevalent factors to have a good surface quality.To this end the choice of a thing rigid and damping tool is essential for any trial run and any industrial machining in series.

Exploration of Desirability Function Analysis-Based Particle Swarm Optimization for Magnetic Abrasive Finishing of Mild Steel

Analysis of surface roughness, temperature and hardness of the finished surface is beneficial to retain the desired surface finish of the workpiece via the magnetic abrasive finishing (MAF) process. In this work, “change in roughness” ([Formula: see text]Ra), “raise in temperature” ([Formula: see text]) and “change in hardness” ([Formula: see text]) were opted for the multi-objective meta-heuristic optimization to minimize their impact on the finished surface of mild steel. Taguchi [Formula: see text] orthogonal array was used to obtain the experimental data on mild steel. The desirability fitness function (DFF) was developed to convert multi-responses to a single response. Finally, particle swarm optimization (PSO) was used for a higher-level decision-making and a meta-heuristic optimization approach, i.e. desirability function analysis-based PSO (PSO-DFA), was developed to obtain the best performance condition for surface finish. The best optimal setting obtained by using PSO-DFA included a working gap of 1.5[Formula: see text]mm, an abrasive weight of 15[Formula: see text]g, a voltage of 6[Formula: see text]V and a rotational speed of 50[Formula: see text]rpm. This setting has been selected based on the highest PSO-DFA value predicted by the meta-heuristic optimization approach and improved by 38.20% in comparison with DFA, that shows a satisfactory performance.