Abstract Abrasive Water Jet Research Articles

Research on Abrasive Water Jet Milling of the Planar Surfaces, Slots and Profiles

Abrasive Water Jet is an innovative process which proves to be a good solution for cutting, drilling, polishing and milling, for various materials. Abrasive Water Jet milling has some advantages, compared with classical technologies, such as: high flexibility and machining versatility, no thermal distortion. In this paper the authors proposed a few strategies for water jet milling manufacturing. Using the correct processing strategies and proper process parameters, water jet milling is a good solution to manufacture plan surfaces, profiles and slots.

An exploration of an abrasive water jet cutting front profile

Abrasive water jet (AWJ) now is used as a precision cutting tool. With this tool, dimension tolerance less than 0.1 mm is expected in the cutting process. This dimension tolerance is enough for some applications. However, higher precision is necessary in order to use AWJ in some other applications. To get higher precision in an AWJ cutting process, controlling AWJ beam more accurately is needed, and this further leads to understanding AWJ cutting front more accurately. This paper compared the current cutting front profile exploration methods and then provided a new method to collect AWJ cutting front information accurately. With this new method, a better understanding of the cutting front profile is possible, which further leads to higher precision cutting of AWJ. This paper also demonstrated that the AWJ cutting front profile could be fitted by parabolic curves accurately.

Effect of workpiece heat treatment on surface quality of AWJ kerf

Abrasive water jet (AWJ) can be effectively employed on a broad selection of work materials, ranging from polymers to lapideous materials and high grade steels. The AWJ cutting process involves several variables, including hydraulic, abrasive, mixing and cutting parameters. Moreover workpiece properties, mainly modulus and hardness, affect material removal type (cutting and deformation wear mode). This paper concentrates on the influence of the mechanical properties of the workpiece on kerf roughness that is achieving more and more attentions from manufacturers, aiming towards near net shape production. In particular, the same carbon steel (C40 UNI EN 10083-2) was used for all tests; two heat treatments were performed on different specimen sets. AWJ cuts on 'as is' (normalised) and hardened specimens (water-quenched) were realised using different traverse speed. The surface roughnesses of the kerfs at different depths were measured to evaluate process performance. A statistical analysis was carried out to assess the significance of the results. It was found that workpiece hardness affects surface finish in different ways, depending on water pressure, traverse rate and depth of measurement across the kerf. Such results support the theory about two different material removal mechanisms, activated at different levels of jet erosive power.

An SPH Simulation on Vibration Assisted Abrasive Erosion of Hard Brittle Material in Abrasive Waterjet Machining

Abrasive waterjet machining (AWJ) is one of the fastest growing non-conventional machining methods. However, low pressure and fine abrasive implemented in AWJ precision machining for reducing the surface damage reduce the efficiency. Therefore ultrasonic vibration is considered to apply on the workpiece to improve the machining efficiency. In order to analyze the effect of the vibration on erosion in AWJ machining, smoothed particle hydrodynamics (SPH) is used to simulate the erosion process for avoiding the mesh distortion in finite element method (FEM) when simulating large deformation and high strain rate problems. The results show that the application of ultrasonic vibration can effectively improve the erosion rate due to the dynamics variation of the erosion process.

The Metal Sheets Processed by AWJ. Analysis of the Surface Quality

Abrasive water jet (AWJ) is a nonconventional machining process in which abrasive grains in a high-speed water jet collide with the sample and erode it. This technology has been developed as an alternative to the conventional processes in order to facilitate the processing of hard materials as stainless steel, titanium alloys, composite materials, etc. However, it is not limited only to hard materials, since it has been successfully applied to process softer materials as aluminum, copper, plastics. Also, the abrasive water jet technology can be used both, to process thin metal sheets and plates since it offers many advantages such as: good surface quality, no thermal distortions, minimal burrs, low machining force, high flexibility. The aim of the current paper was to study the surfaces quality of samples made by aluminium, A1050, processed by AWJ in case of using different working regimes. The experimental tests have been performed on the Hydro-jet Eco 0615 water jet cutting machine. The parameters that have been varied were pressure, feed rate, abrasive quantity, distance between the cutting head and working sample while the diameter of focusing tube and diameter of water nozzle have been kept constant. The parameters taken into account to quantify the quality of the processed surface were those defined in the ISO/WD/TC 44 N 1770 standard (fig. 1): width of the processed surface at the jet inlet (Li), width of the processed surface at the jet outlet (Lo), deviation from perpendicularity (u), inclination angle (α) and roughness (Ra).

The Influence of the Feed Rate on the Quality of Surfaces Processed by AWJ at High Pressures

Abrasive water jet processing is one of the newest unconventional technologies. It can be used to cut different metallic materials (steel, titanium alloys, aluminium alloys, brass) or non-metallic materials (wood, plastics, glass, stone, granite etc.). Therefore, this technology can be successfully applied in different industries as: food industry, wood industry, aeronautic industry, automobile industry, mining industry. Between the advantageous of abrasive water jet processing technology it is worth noticing the following: it is rapid, very small processing forces are generated, it is silent, no thermal distortions occur. The aim of the current paper was to determine the influence of the feed rate on the quality of surfaces processed by AWJ at high pressure. The parameters that quantified the quality of the processed surface were those defined in the ISO/WD/TC 44 N 1770 standard: width of the processed surface at the jet inlet (Li), width of the processed surface at the jet outlet (Lo), deviation from perpendicularity (u), inclination angle (α) and roughness (Ra).

An Experimental Research on Abrasive Water Jet Polishing of the Hard Brittle Ceramics

Abrasive water jet (AWJ) technology, due to its potential advantages, is a promising machining method for precision machining brittle materials. In this research, the AlN ceramics was polished using an AWJ machining system. A considerable processing quality has been achieved and a reduction up to 62% of the surface roughness has been obtained. Effects of different process parameters on the surface roughness of the polished workpiece were analyzed. Under the current conditions of the experiments, using a lower impact angle, smaller abrasives and a lower nozzle traverse speed may be appropriate for polishing AlN ceramics.

Impact Erosion of Quartz Crystals by Micro-Particles in Abrasive Waterjet Micro-Machining

Abrasive waterjet (AWJ) micro-machining is a precision processing technology with some distinct advantages. To understand the machining process, the erosion mechanism is presented and discussed when micro-particle impacting on a quartz crystal specimen. It is found that three types of impressions are formed which are craters, micro-dents and scratches. Small-scale craters including crashed zones and radial cracks are associated with plastic flow and subsurface micro-cracks that decrease the material strength, but cause little material removal, while large-scale craters including conchoidal fractures caused by the propagation of lateral cracks dominate the volume change of the specimen. Micro-dents are produced by the impact of particles possessing small kinetic energies, and scratches are generated by particle sliding or rolling over the target surface and make a negligible contribution to material removal. The crater volume generated by the impact of individual particle is then discussed with respect to particle impacting velocity and impact angle. It shows that an increase in particle impact angle or particle velocity increases the crater volume due to the increased conchoidal fractures during the impact process.

Study on the Effect of Standoff Distance on Processing Performance of Alumina Ceramics in Two Modes of Abrasive Waterjet Turning Patterns

Abrasive waterjet (AWJ) turning is an emerging technology, which plays an important role in machining cylindrical parts with the distinct advantages of negligible thermal effects and extremely low cutting force. This paper presents an experimental study of abrasive waterjet turning (AWJT) of Al2O3ceramics. The machining process and performance in terms of the depth of penetration (DOP), surface roughness (Ra) and actual impact angle (β) are discussed to understand the effect of standoff distance (SOD) on the processing performance at two different turning modes. Based on the results of these investigations, there is a significant change ofDOPandRaat differentSODin radial mode turning and the optimalSODof gaining maximumDOPand the minimumRais about 5.5mm.However, theDOPis nearly independent on theSODin offset mode turning. SmallerRaandDOPcan be obtained in offset mode. Furthermore, the results indicate that the roundness error of cylinder parts is probably improved with the properSODinterval in radial mode turning and it is suitable for machining cylinder part with considerably different radial size. The offset mode turning as the next operation after radial mode turning is recommended to process workpiece with excellent roundness. In this way, by understanding the effect ofSODon processing alumina ceramics, the paper establishes a good basis for developing strategies for optimizing processing parameters in order to generate the desired part geometry and achieve better surface quality.

AN EXAMINATION OF ABRASIVE WATERJET PEENING WITH ELASTIC PRE-STRESS AND THE EFFECTS OF BOUNDARY CONDITIONS

Abrasive Waterjet Peening (AWJP) has emerged as a potentially viable method of surface treatment for components requiring compressive residual stress and a rough surface texture. In the present investigation the residual stress distributions resulting from AWJP of Ti6Al4V with load and displacement control flexure pre-stress were compared. An experimental evaluation was conducted to quantify the variations in the residual stress characteristics (magnitude and depth) as a function of boundary conditions over a pre-stress ranging from 0 to 75% of the material's yield strength. In addition, a finite element model for indentation-based surface treatments was developed to investigate the mechanisms contributing to the observed trends in experimental results. Overall, AWJP of the Ti6Al4V resulted in a surface residual stress ranging from approximately 800 to 1600 MPa. Load control pre-stress resulted in a larger surface residual stress (up to 50% greater) than that achieved under displacement control treatments. Although the maximum surface residual stress was obtained at the largest applied pre-stress, the difference between load and displacement control treatments decreased with pre-stress magnitude. Boundary conditions had limited influence on the depth of residual stress achieved, but were important to the depth of plasticized zone beneath the treated surface.

A Cross-Sectional TEM Study of Abrasive Water Jet Cut Surface

Abrasive Water jet cutting (AWJ) is a process used to cut materials using a jet of pressurized water. These water jets are capable of cutting a variety of materials like superalloys, titanium alloys, stainless steel, tool steels, ceramics, armor tool and granite. In the present study an attempt has been made to investigate microstructural changes taking place in the sub-surface as a result of AWJ cutting using cross-sectional Transmission Electron Microscopy (TEM). TEM analysis shows that the sub-surface of the AWJ machined sample surface experienced severe deformations. The surface microstructure is observed to contain extremely fine sized grains, going down from sub-micrometer to nanometer range. The selected area diffraction pattern analysis also confirms the presence of extremely fine grained microstructure.

Capability of Advanced Abrasive Waterjet Machining and its Applications

Abrasive waterjet machining has been recently considered as a promising, emerging non-conventional technology with an extensive growth in its market share and research activities. In this paper, a Europe’s first 5-axis AWJ system established at the University of Nottingham will be introduced followed by some of the research works explored on the capability of AWJ machining (e.g. AWJ cutting, AWJ drilling, AWJ milling, AWJ turning) on exotic materials such as Ti-based alloys at different niche applications. Thanks to advances in the complementary AWJ technology (e.g. ultra-high pressurized pump) and advanced machine designs (e.g. multi-axis machine movement), it was found that the machining capability of abrasive waterjet (even plain waterjet) can be extended if innovative strategies are applied.

Determination of rotary cutting depth on steel pipes with the abrasive water jet technique

Abrasive water jet (AWJ) cutting is a green machining and processing technology that has found extensive applications. In this study, a well-designed cutting tool with multiple AWJ nozzles has been developed to determine the rotary multi-pass cutting depth on steel pipes that are used in petroleum industries. Experimentally, the multi-pass AWJ cutting depth is found to increase with pump pressure, nozzle diameter, and number of nozzles, but decrease with standoff distance. Also, the multi-pass cutting depth initially increases with rotation speed of the AWJ cutting tool or volumetric concentration of abrasive, and then begins to decline when rotation speed or volumetric concentration reaches a certain value. Mathematically, an empirical model is formulated to determine the rotary cutting depth initiated by multiple cutting passes based on the energy conservation theory. There exists a good agreement between the experimentally measured and theoretically calculated cutting depths with a percentage average absolute deviation of 7.0 per cent.

An Evaluation of Abrasive Waterjet Peening With Elastic Prestress

Abrasive waterjet peening (AWJP) has been conceived as a new surface treatment process capable of achieving desired changes in surface texture, chemistry, and residual stress simultaneously. In the present investigation, the influence of elastic prestress on the residual stress resulting from AWJP was studied. Treatments were conducted on steel, as well as nickel and titanium alloy targets subjected to an elastic prestress ranging from 0% to 75% of the material’s yield strength. The results showed that a tensile elastic prestress increases the surface residual stress and the depth of the compressive stress zone. The surface residual stress in each metal increased nonuniformly with magnitude of prestress; the maximum surface residual stress was obtained at an applied prestress between 45% and 60% of the substrate yield strength. Overall, the increases in surface stress and depth that were obtained reached 100% and 50%, respectively. There were no changes to the surface texture caused by the prestress. According to results of this study, application of an elastic prestress can serve as an effective method for improving characteristics of the residual stress field in components treated using AWJP.

Neural network parametric modelling of abrasive waterjet cutting quality

Abrasive Waterjet (AWJ) can provide very effective means for shape cutting of difficult-to-machine materials. One of the principal deficiencies of AWJ cutting process is the wavy striation on the generated cut surface in relatively thick workpieces or high traverse speed. It is therefore essential to predict the main AWJ processing parameters to achieve a desired cutting quality. But many aspects about this technology are neither fully understood nor have they been accurately modelled. In this paper, based on the experimental data, an Artificial Neural Network (ANN) parametric model of AWJ cutting process was developed and used in CNC machines. The predicted results indicated that the model could identify the cutting quality to a high desirable accuracy, and the ANN can be used as an appropriate method for prediction of cutting parameters in AWJ systems.

Recent Development of Abrasive Water Jet Machining Technology

Abrasive waterjet (AWJ) machining is a new non-conventional machining technology. Compared with other conventional and non-conventional machining technologies, AWJ offers the following advantages: no thermal distortion, small machining force, high machining versatility, etc. Therefore this technology is regarded as a high potential technology in the field of machining difficult-to-cut materials. In this paper, a comprehensive review of research situation about the cutting performance, the cutting mechanism and the measures to improve the cutting quality is given. The application of abrasive waterjet machining in turning, milling and drilling is reviewed finally.