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In abrasive waterjet (AWJ) process, abrasive properties are of critical factors that influence machining performances. Abrasive process parameters including abrasive material, size and flow rate, exert a significant impact on cutting ability and quality of AWJ. In this paper, monolithic abrasive material (garnet, alumina and silicon carbide) and corresponding mixing abrasive materials are adopted to evaluate the effect of abrasive process parameters on the cutting ability and quality, respectively. Two kinds of cutting experiments are conducted with a monolithic abrasive to explore the influence of variation in abrasive material, size and flow rate on the machining performance. The cutting depth experiments for evaluating the cutting ability in terms of cutting depth are conducted with a right trapezoid aluminium alloy block. The kerf cutting experiments are taken to evaluate the cutting quality by the kerf taper angle, kerf width and surface roughness. On this basis, AWJ experiments with mixing abrasive materials are taken to probe into the composition of mixing abrasives’ effect on cutting performance. It is found that the abrasives consisting of 75% alumina and 25% garnet in mass fraction lead to a maximum cutting depth of 41.7 mm and the smallest surface roughness of R a 2.1 μm under the flow rate of 130 g/min.

The abrasive waterjet machining process was introduced in the 1980s as a new cutting tool; the process has the ability to cut almost any material. Currently, the AWJ process is used in many world-class factories, producing parts for use in daily life. A description of this process and its influencing parameters are first presented in this paper, along with process models for the AWJ tool itself and also for the jet–material interaction. The AWJ material removal process occurs through the high-velocity impact of abrasive particles, whose tips micromachine the material at the microscopic scale, with no thermal or mechanical adverse effects. The macro-characteristics of the cut surface, such as its taper, trailback, and waviness, are discussed, along with methods of improving the geometrical accuracy of the cut parts using these attributes. For example, dynamic angular compensation is used to correct for the taper and undercut in shape cutting. The surface finish is controlled by the cutting speed, hydraulic, and abrasive parameters using software and process models built into the controllers of CNC machines. In addition to shape cutting, edge trimming is presented, with a focus on the carbon fiber composites used in aircraft and automotive structures, where special AWJ tools and manipulators are used. Examples of the precision cutting of microelectronic and solar cell parts are discussed to describe the special techniques that are used, such as machine vision and vacuum-assist, which have been found to be essential to the integrity and accuracy of cut parts. The use of the AWJ machining process was extended to other applications, such as drilling, boring, milling, turning, and surface modification, which are presented in this paper as actual industrial applications. To demonstrate the versatility of the AWJ machining process, the data in this paper were selected to cover a wide range of materials, such as metal, glass, composites, and ceramics, and also a wide range of thicknesses, from 1 mm to 600 mm. The trends of Industry 4.0 and 5.0, AI, and IoT are also presented.

The abrasive and rock properties have a significant impact on the performance and profitability of abrasive water jet (AWJ) cutting. In the relevant literature, there is no comprehensive study that investigates the effects of abrasive type on the AWJ cutting of rocks. As a result, in the current study, various abrasives (garnet, white fused alumina, brown fused alumina, glass beads, emery powder, olivine, steel shot, and plastic granule) were used in tests where workpieces prepared from various rock types (igneous, metamorphic, and sedimentary) were cut with AWJ. The cutting parameters were kept constant during the cutting operations. The cutting depth was taken into account when evaluating the AWJ performance. It was revealed that garnet, steel shot, and fused alumina (brown and white) have higher cutting abilities (cutting depth: 39.23–125.94 mm by the rock type). Compared to them, olivine, emery powder, and glass bead produced shallower cuts (21.11–80.00 mm by the rock type). Despite this, effective cutting did not occur with plastic granules. It was demonstrated that there are strong correlations between the cutting depth-abrasive hardness (up to r: 0.82 by rock type) and cutting depth-abrasive density (up to r: 0.87 by rock type). It was determined that the cutting depth increases as the Bohme abrasion loss, effective porosity, and water absorption capacity of the rocks increase. It was also found that the cutting depth decreases as the strength, Schmidt hardness, unit volume weight, and ultrasonic wave velocity of the rocks increase. The most essential rock properties influencing cutting depth were determined as the Bohme abrasion loss, uniaxial compressive strength, and point load strength.

Cutting edge preparation has become more important for tool performance. The micro-shape, radius and surface topography of the cutting edge play a significant role in the machining process. The cutting edge of solid carbide end mills has some micro-defects after grinding. For eliminating aforementioned problem, this study investigates drag finishing (DF) preparation for solid carbide end mills to reconstruct cutting edge micro-geometry. This paper is to present the design of DF experimental setup and analyze the characterization of various abrasive media (K3/600, K3/400, HSC 1/300 and HSO 1/100) on the evolution of the surface/roughness along the cutting edge. In parallel, the mechanism of material removal and the kinematics trajectory of the drag finishing are presented. In fact, the form factor (also called as “K-factor”) of the cutting edge micro-geometry is quantified. Comparing with four lapping media, the higher material removal rate (MRR) and the lower surface roughness are obtained by HSO 1/100 abrasive process. The results show that the cutting edge K-factor, MRR and surface topography are influenced by the abrasive particles size, composition and process time.

Multi-particle velocities and trajectories in abrasive waterjet machining are of great value to understand the particle erosion mechanism involved in the cutting process. In this paper, the whole-stage simulation model is established from the high-pressure water and abrasive particles entering the nozzle to the mixed abrasive jet impacting the workpiece based on the SPH-DEM-FEM method. Comparing the simulation results with the experimental results under different process parameters, the capability of the proposed model is systematically validated. The model is applied to study the mixing and accelerating process of abrasive particles, and the results show that a speed difference is existed between the water and abrasive particles after being ejected from the nozzle. In addition, the nozzle wear pattern is also analyzed carefully. It is discovered that the most serious wear happened at the junction of the mixing chamber and the focusing tube. And the focusing tube wear is uneven and spreads downward.

Purpose The surface roughness of additively manufactured parts is usually found to be high. This limits their use in industrial and biomedical applications. Therefore, these parts required post-processing to improve their surface quality. The purpose of this study is to finish three-dimensional (3D) printed acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA) parts using abrasive flow machining (AFM). Design/methodology/approach A hydrogel-based abrasive media has been developed to finish 3D printed parts. The developed abrasive media has been characterized for its rheology and thermal stability using sweep tests, thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The ABS and PLA cylindrical parts have been prepared using fused deposition modeling (FDM) and finished using AFM. The experiments were designed using Taguchi (L9 OA) method. The effect of process parameters such as extrusion pressure (EP), layer thickness (LT) and abrasive concentration (AC) was investigated on the amount of material removed (MR) and percentage improvement in surface roughness (%ΔRa). Findings The developed abrasive media was found to be effective for finishing FDM printed parts using AFM. The microscope images of unfinished and finished showed a significant improvement in surface topography of additively manufactures parts after AFM. The results reveal that AC is the most significant parameter during the finishing of ABS parts. However, EP and AC are the most significant parameters for MR and %ΔRa, respectively, during the finishing of PLA parts. Practical implications The FDM technology has applications in the biomedical, electronics, aeronautics and defense sectors. PLA has good biodegradable and biocompatible properties, so widely used in biomedical applications. The ventilator splitters fabricated using FDM have a profile similar to the shape used in the present study. Research limitations/implications The present study is focused on finishing FDM printed cylindrical parts using AFM. Future research may be done on the AFM of complex shapes and freeform surfaces printed using different additive manufacturing (AM) techniques. Originality/value An abrasive media consists of xanthan gum, locust bean gum and fumed silica has been developed and characterized. An experimental study has been performed by combining printing parameters of FDM and finishing parameters of AFM. A comparative analysis in MR and %ΔRa has been reported between 3D printed ABS and PLA parts.

As an advanced precision machining process, magnetic abrasive finishing (MAF) technology can be applied to grind complex workpieces. However, it is not conducive to formulate an appropriate processing that MAF processing on tubular workpiece has a severe lack of a well-defined material removal rate model. In order to solve this problem, the contact form between the magnetic abrasive and the workpiece surface was simplified, and the force analysis of the magnetic abrasive in the magnetic field was performed. Furthermore, an ideal predictive model on material removal rate was proposed, which was based on both the quantity of active abrasives in the processing area and the depth at which magnetic abrasive was pressed into the workpiece. The correction factor 'k' was determined based on the comparison and analysis of experimental results and theoretical predictions. What is more, the accuracy of the revised model on material removal rate was confirmed. The surface roughness of the workpiece was reduced from 0.213 to 0.058 μm after undergoing 19 cycles of processing under the conditions of spindle speed of 104.7 rad/s, abrasive mass of 3.5 g, processing distance of 2 mm, and a feed rate of 3 mm/s. The material removal rate was 0.140 μm/min, which exhibits an absolute error of 7.675% in comparison to the predicted value of 0.152 μm/min. The results indicate that the model can meet the prediction requirements of material removal rate in the MAF process, and MAF technology can effectively achieve finishing on the inner surface of the tube.

Flow field simulation of abrasive media in a constrained passage in abrasive flow machining (AFM) plays a decisive role in optimising process parameters and designing the core of a fixture. Based on the experimental rheological characterisation of various types of abrasive media, a model of flow field simulation of abrasive media was constructed by combining with the continuous medium hypothesis. Moreover, a pressure detection platform was built for the constrained passage and test and simulated data were compared and analysed. The results demonstrate that the diameter of abrasives slightly affects the rheological characterisation of abrasive media under the same mass fraction, and rheological characterisation of abrasive media before and after use obeys a power-law constitutive model. Simulated pressures in the flow field show a completely consistent trend with measured pressures although they deviate significantly in the inlet region. Pressure in the constrained passage increases with increasing extrusion pressure and gradually attenuates along the flow direction, so that abrasive finishing marks become shallower along the flow direction. In addition, the increased extrusion pressure increases the final surface roughness of the polished surface and extends the processing time required to stabilise the final surface quality.

Molecular dynamics simulation of double-grits interacted grinding of GaN crystals is performed. Interacted distance with both radial and transverse directions is better than that with only one direction or single-grit grinding. Girt-interactions decrease force, friction coefficient, stress, damage depth, and abrasive wear. Amorphous, phase transition, dislocation, stacking fault and lattice distortion dominate plastic damage. Elucidating the complex interactions between the work material and abrasives during grinding of gallium nitride (GaN) single crystals is an active and challenging research area. In this study, molecular dynamics simulations were performed on double-grits interacted grinding of GaN crystals; and the grinding force, coefficient of friction, stress distribution, plastic damage behaviors, and abrasive damage were systematically investigated. The results demonstrated that the interacted distance in both radial and transverse directions achieved better grinding quality than that in only one direction. The grinding force, grinding induced stress, subsurface damage depth, and abrasive wear increase as the transverse interacted distance increases. However, there was no clear correlation between the interaction distance and the number of atoms in the phase transition and dislocation length. Appropriate interacted distances between abrasives can decrease grinding force, coefficient of friction, grinding induced stress, subsurface damage depth, and abrasive wear during the grinding process. The results of grinding tests combined with cross-sectional transmission electron micrographs validated the simulated damage results, i.e. amorphous atoms, high-pressure phase transition, dislocations, stacking faults, and lattice distortions. The results of this study will deepen our understanding of damage accumulation and material removal resulting from coupling between abrasives during grinding and can be used to develop a feasible approach to the wheel design of ordered abrasives.