Abrasive Water Jet Process Research Articles

Influence of the damage generated by abrasive water jet texturing on the tensile static and fatigue behaviour of 3D woven composite in the context of repair

Abrasive water jet (AWJ) process has been certified in some aerospace companies for repair applications. However, there is no information in the literature on the influence of the induced damage on the mechanical behaviour of complex materials such as 3D woven CFRP composite. To fill this gap, three texturing levels have been produced and quantified using both surface roughness (Ra) and “crater volume” (Cv) criteria. The specimens have been subjected to tensile static and tension-tension fatigue tests. Contrarily to Ra measurements, a linear correlation was highlighted between the increase in Cv and the degradation of the specimens’ mechanical performances (ultimate tensile stress and fatigue limit). The damage scenario of the textured specimens has been identified via acoustic emission activity, thermal maps and X-ray tomography pictures. Wider cracks and a more intense acoustic activity leading to a greater rise in temperature have been observed when Cv increases (worse quality). However, the small alterations in mechanical properties consecutive to AWJ texturing prove that this technique can be used for surface preparation of 3D woven CFRP parts prior to bounding without damaging them. Moreover, an innovative method, based on the damage accumulation, has been proposed and accurately estimates the endurance limit of the specimens.

Experimental Study of Abrasive Waterjet Cutting for Managing Residues in No-Tillage Techniques

A laboratory investigation of abrasive waterjet cutting of wheat straws was conducted. The work was aimed at a systematic characterization of the abrasive waterjet cutting capability of wheat straws, as a potential alternative to cutting discs currently adopted in no-till drills and planters for crop residue management. A two level 2IV7−3 fractional factorial design was applied to investigate the influence of abrasive waterjet process parameters on the cutting efficiency of wheat straws. Straw coverage thickness, water pressure, and orifice diameter were found to be the most significant ones. Experimental results suggest that straw cutting mechanism is mostly related to the hydraulic power of the jet. A multiple logistic regression was performed to model the relationship between the cutting efficiency and the jet power. The logistic model was then applied to estimate the average water and power consumption for wheat straw cutting during a no-tillage seeding operation. An average jet hydraulic power of 6400 W would be sufficiently high to guarantee 90% cutting efficiency in presence of heavy residue distribution. The experimental study shows that a small quantity of abrasive powder (50 g·min−1) allows one to increase the jet cutting capability of wheat straws, and to reduce the required maximum hydraulic power, compared to pure waterjet cutting. Results show are potentially relevant for field validation in agriculture based on no-tillage.

Multi-scale characterization of material and surface integrity of Inconel 718 when milling by Abrasive Water Jet process: Context of repair application

Inconel 718 (IN718) is a precipitation hardened nickel-base super-alloy exhibiting poor machinability and used in the hot section of aircraft engines. These components are subjected to severe thermo-mechanical loads in a highly corrosive environment, limiting their service life due to cracks and wear. Due to their high added-value, repair of damaged IN718 components is an interesting alternative instead their replacement. Repair process involves material removal of the damaged zone and subsequent cavity refill. Nevertheless, material removal of IN718 by conventional methods is a challenging task. Abrasive Water Jet (AWJ), a non-conventional machining process, offers a potential alternative to mitigate IN718 machining problems. However, research on the impact of AWJ process parameters during IN718 milling on the surface and material integrity is limited in the literature. Furthermore, in repair context, no study proposes AWJ machining as material removal process. The present work focuses on a multi-scale characterization of the influence of AWJ process parameters (pressure, traverse speed, step-over distance and abrasive size) on surface roughness, depth of cut, abrasive embedment and residual stress, during milling of untreated IN718. Surface integrity characterization on the milled surfaces was conducted through 3D optical microscopy, profilometry and SEM techniques. Residual stress measurements were performed in longitudinal and transverse directions with respect to the machining path using XRD technique. The results showed that all milled surfaces presented abrasive embedment and a compressive residual stress state with similar values in both directions. Up to 15% of the area of a milled surface consisted of abrasive embedment. The tool path has not influenced the residual stresses. Furthermore, surface roughness is dependent on pressure and traverse speed; depth of cut is influenced by pressure, traverse speed and grit size; abrasive embedment depends on pressure, step-over distance and grit size; whilst, residual stresses are influenced by traverse speed and grit size.

Influence of abrasive water jet parameters on the surface integrity of Inconel 718

Inconel 718 (IN718) is a precipitation hardened nickel-base super-alloy exhibiting high strength and good corrosion resistance at elevated temperatures and on the downside; it is characterized by poor machinability. Abrasive water jet (AWJ) process offers a potential method to machining difficult-to-cut materials such as IN718. The present work investigates the influence of AWJ parameters on surface roughness, topography, depth of cut, and residual stress when milling IN718. Surface characterization was conducted through 3D optical microscopy and SEM techniques. Residual stresses were measured in longitudinal and transverse directions with respect to the machining path using X-ray diffraction (XRD) technique. The obtained results showed that milled surfaces have a homogeneous texture with embedded abrasive particles and high surface roughness. AWJ process introduced high compressive residual stresses with similar order of level in both directions (X and Y). In addition, it was observed that jet pressure is the most influencing parameter on roughness and depth of cut, whilst traverse speed and step-over distance had a significant effect on the residual stress. Based on the experimental analysis, an empirical model to predict the depth of cut was proposed. The validation of the proposed model has shown around 5% error in the predicted and actual pocket depth.

Plain water jet cleaning of titanium alloy after abrasive water jet milling: Surface contamination and quality analysis in the context of maintenance

Abrasive water jet (AWJ) milling process, though being an effective alternative to conventional machining for difficult-to-machine materials, induces abrasive embedment which is an issue for repair application by structural bonding. In this context, the effectiveness of cleaning Ti6Al4V specimens by Plain Water Jet (PWJ) post AWJ milling is studied. For this, Ti6Al4V specimens are milled by AWJ process with varying parameters to create several levels of surface quality and contamination. Different characterization techniques have been used to perform a multi-scale analysis of the machined surfaces and surface quality has been quantified by an innovative criterion called “crater volume” (Cv). Then the specimens are subjected to PWJ cleaning operation (using a single set of parameters chosen after preliminary study). Finally, surface texture analysis and contamination quantification is performed and compared with the AWJ milled surfaces. The results revealed that PWJ cleaning reduced the surface contamination by 65% without any significant change in Cv, surface texture and topology. However, it was found that it was impossible to dislodge deeply embedded particles. The comparison of pre and post-cleaning contamination levels also revealed that PWJ cleaning process efficiency depends on the AWJ milling parameters (mainly pressure).

The effect of machining processes on the physical and surface characteristics of AA2024-B4C-SiC hybrid nanocomposites fabricated by hot pressing method

In this study, an attempt was made on the AA2024 alloy based hybrid nanocomposites reinforced with different weight percentage of SiC and B4C particles to investigate their physical and machinability characteristics including surface morphology. The Material Removal Rate (MRR), Surface Roughness (SR) of the nanocomposites machined by various machining processes namely Abrasive Water Jet (AWJ) machining, Wire Electrical Discharge (WED) machining and Computer Numerical Controlled (CNC) turning processes were studied comparatively. The machined surface formed by the each machining process is examined and its surface quality was discussed for each hybrid nanocomposite. Results show that the hardness is increased to 101.6 BHN from 179.4 BHN, when 2 wt.% of B4C and SiC particles is added to AA2024 matrix. Observed from the results that the addition of 2 wt.% of B4C and SiC particles produces the highest porosity of 3.36% for nanocomposite samples. The experimental results revealed that the addition of particulates in to the matrix reduces the MRR and increases SR. MRR results showed that hybrid nanocomposites machined by AWJ technique has minimum MRR of 0.0221 mm3/min. The surface roughness of the nanocomposites machined with AWJ process was 3.2 µm and increased to 6.81 µm for the AA2024-B4C-SiC hybrid nanocomposites machined with CNC process.

Optimization of SiC Abrasive Parameters on Machining of Ti-6Al-4V Alloy in AJM Using Taguchi-Grey Relational Method

In this research, multi response Taguchi-grey relational approach was employed to optimize the machining parameters of Ti-6Al-4V alloy in abrasive water jet process. The main aim of this present investigation was to explicate the role of adding SiC super hard ceramic into the garnet and to find out the optimal input variable, which is influencing the material removal rate and surface finish in the process. The specific input variables such as SiC volume, SiC size and abrasive flow rate were accounted as potential process variables for this present investigation. It is observed that the SiC along with garnet improves the material removal rate. According to the analysis the SiC addition of 0.5 wt.%, SiC size of 80mesh and abrasive flow rate of 2 g/s (A2B1C1) was found to be producing MRR of 48.81 mm3/s and lower surface roughness of 3.72 μm. From study the particle size was the most influential parameter for producing high MRR with low surface roughness. The confirmation study reveals the improvement of 1.91% in MRR and surface roughness on comparing with predicted mean value.

Evaluation and Optimization of Geometric Deviations in Abrasive Water Jet Profile Cutting of Inconel 617

Abstract Inconel 617, an extremely hard-to-machine nickel-based superalloy, is used for high-temperature applications in ultra-supercritical power plants for components like headers, pipes, and turbine blades. Conventional machining of superalloys has been widely explored and is plagued by productivity and quality issues. Nontraditional processing is seen as an effective alternative, and abrasive water jet is a capable method. Optimization involving weighted principal components and a genetic algorithm is detailed for the abrasive water jet process. Water pressure, abrasive mass flow, stand-off distance, and traverse speed are the predominant factors affecting the process. Performance characteristics are material removal rate and surface roughness. Geometric deviations like circularity, cylindricity, perpendicularity, and parallelism, which are mostly neglected, have been investigated. Analysis of variance has been reported indicating the predominant factors. Geometric deviations are consolidated into a geometric index using weighted principal components. Simultaneous multiresponse optimization is performed using multi-objective genetic algorithm and a Pareto-front. From the Pareto-front a geometric index of 0.02036 was obtained at water pressure of 266.03 MPa, standoff distance of 4.27 mm, abrasive mass flow of 0.41 kg/min, and traverse speed of 58.98 mm/min. Material removal rate of 495.42 mm3/min was obtained at water pressure of 266.29 MPa, standoff distance of 4.48 mm, abrasive mass flow of 0.40 kg/min, and traverse speed of 63.11 mm/min. Surface roughness of 6.6364 μm was obtained at water pressure of 266.43 MPa, standoff distance of 4.43 mm, abrasive mass flow of 0.42 kg/min, and traverse speed of 57.48 mm/min. The sets obtained are a compromise between the different output values and provide an optimal parameter setting for the abrasive water jet process. This tool is essential when a large database is available, and it could be used to obtain a set of solutions based on the different machining characteristics that are required from the process.

Empirical Modeling of Abrasive Waterjet Process for Controlled Depth Machining of Dense Segmented Ceramic Thermal Barrier Coatings

Abrasive waterjet (AWJ) controlled depth machining shows promise to be one of the most efficient non-conventional structuring techniques for dense segmented Thermal Barrier Coatings (STBC) on turbomachinery hot gas components made of Yttria-Stabilized Zirconia. Exemplary applications in the field of gas turbine technology are engraving of structures to optimize gas turbine performance and the stripping process of TBC within the repair process chain. As there are no comprehensive process models available, the development of an appropriate AWJ machining process is demanding. Thus, deeper process understanding and modeling need to be investigated.This paper shows an empirical modeling of AWJ process for controlled depth machining of dense segmented TBC material. The practical trials are based on a Design of Experiments (DoE). The investigated influencing parameters are water pressure, abrasive mass flow, feed rate, hatch distance and machining angle. The considered target variables are ablation depth and surface roughness. Furthermore, the process stability is investigated. The developed empirical model results in an acceleration of process parameter determinations.

Quantitative analysis on the surface topography of Ti-6Al-4V machined by abrasive suspension jet

Surface topography is the intrinsic determinant of the roughness that is a significant evaluation standard for the machining quality of the abrasive suspension jet (ASJ). To achieve quantitative analysis on the surface topography machined by ASJ, this paper measured the roughness and the scratch size of the cutting surface with an ultra-deep three-dimensional microscope. Ti-6Al-4V (TC4), a typical hard machining material widely used in aviation industry, was chosen as the cutting target. From a macroperspective, the cutting surface is divided into four zones from top to bottom including the initial zone, the smooth zone, the transition zone, and the rough zone. With 1.6-μm set as the standard roughness, the length of the initial zones and the smooth zone were analyzed and determined. From a microperspective, there are a large number of particle scratches with micron scale size laid on the cutting surface. The experimental results showed that the length of the scratches in the initial zone was less than the one in the smooth zone, while it was opposite in the scratch depth and width, and that the initial zone is larger than the smooth zone in surface roughness could be explained. The abrasive particle size is the only influent parameters of the scratch size, and small abrasive particles can be used for reducing the roughness in the initial zone and smooth zone. The conclusions can provide theory guidance for abrasive water jet processing titanium alloys precisely.

Modelling surface quality of abrasive water jet processing at multi-objective optimization criteria

Al–Mg alloys belong to high mechanical properties aluminum alloys. They are used for different industries such as: automotive, and ship building, etc. Most of these industries depend on large sheet processing. Productivity of the used conventional processing techniques is considered a drawback specially for large plates cutting. High processing temperature can deteriorate the cut material properties. Abrasive water jet process (AWJ) is one of the modern nontraditional machining processes. It can be used for cutting most of materials with approximately zero thermal effect and relatively high cutting speed. Despite the high productivity of this technique, however quality of the cut surface is considered a challenge. During this study AWJ technique will be investigated for understanding the cutting quality behavior at high cutting speed without forfeiting the cutting quality. A control model is developed to understand the interactive relation between the control factors and output responses of the cutting process. It can be used for: prediction the surface behavior at different control parameters combinations, and recommend the control parameters which satisfy a certain surface quality. Cutting speed, main stream pressure, and (stand-off distance) were employed as control factors. Quality of cutting process will be assessed in terms of surface roughness, striation forming, kerf width, and cut taper angel. Model is optimized and verified experimentally at different conditions to evaluate the accuracy of the model prediction. The model validation shows a very good correlation between the experimental and optimization results.

Influence of Variable Radius of Cutting Head Trajectory on Quality of Cutting Kerf in the Abrasive Water Jet Process for Soda-Lime Glass.

The main innovation of this article is the determination of the impact of curvature of a shape cut out in a brittle material using an abrasive water jet (AWJ) process as an important factor of the machined surfaces. The curvature of a shape, resulting from the size of the radius of the cutting head trajectory, is one of the key requirements necessary for ensuring the required surface quality of materials shaped by the abrasive water jet process, but very few studies have been carried out in this regard. An important goal of the experimental studies carried out here and presented in this work was to determine its influence on the quality of the inner and outer surfaces of the cutting kerf. This goal was accomplished by cutting the shape of a spiral in soda–lime glass. For such a shape, the effect of radius of the trajectory of the cutting head on selected parameters of the surface texture of the inner surface of the cutting kerf (IS) and the outer surface of the cutting kerf (OS) was studied. The obtained results of the experimental studies confirmed that the effect of the curvature of the cut shape is important from the point of view of the efficiency of the glass-based brittle material-cutting process using AWJ. Analyses of the surface textures of the areas located in the upper part of the inner and outer surfaces separated by the use of AWJ machining showed that the OS surfaces are characterized by worse technological quality compared with IS surfaces. Differences in the total height of surface irregularities (given by St amplitude parameter), determined on the basis of the obtained results of the measurements of both surfaces of the cutting kerf, were as follows: ΔStr = 50 = 0.6 μm; ΔStr = 35 = 1 μm; ΔStr = 15 = 1.3 μm. The analysis of values measured in areas located in the more sensitive zone of influence of the AWJ outflow proved that the total height of irregularities (St) of the OS was higher. Differences in the total heights of irregularities for inner and outer surfaces of the cutting kerf were as follows: ΔStr = 50 = 2.1 μm; ΔStr = 35 = 3 μm; ΔStr = 15 = 14.1 μm, respectively. The maximum difference in the total heights of irregularities (St), existing between the surfaces considered in a special case (radius 15 mm), was almost 20%, which should be a sufficient condition for planning cutting operations, so as to ensure the workpiece is shaped mainly by internal surfaces.

Multi-scale analysis of the generated damage when machining pockets of 3D woven composite for repair applications using abrasive water jet process: Contamination analysis

Repair of damaged aircraft structural parts is a regular maintenance activity carried out to preserve airworthiness while being economically viable. Conventional repair techniques used have negative impact on the repair quality and environment due to dust emission. For eliminating aforementioned problem, this study investigates controlled depth abrasive water jet (AWJ) milling for repair procedure of 3D woven CFRP composite structures used in the new aircraft engine developed by Safran Aircraft Engines. The aim is to identify and quantify the damage and surface contamination induced by AWJ milling. For this, the influence of milling parameters on the damage and surface contamination is investigated through full factorial experimental study. Several characterisation techniques like 3D optical profilometry, Scanning Electron Microscopy and X-ray tomography combined with image processing were used for a multi-scale analysis of the machined surface damage and contamination. In fact, the machining quality was quantified using an innovative criterion called “crater volume” (Cv). The obtained results have shown surface contamination by embedded abrasive particles and presence of bare and broken fibres, cracks, craters. The results show that the rate of contamination is influenced by the jet pressure and the scan step and the Cv is influenced by the jet exposure time.

Analysis of the initial damage region in agate plates cut by abrasive waterjet (AWJ) process

The abrasive waterjet (AWJ) cutting process has been widely used in the gemstone processing industry due to its versatility and accuracy characteristics. The influence of the parameters involved in the AWJ process has been investigated by many authors, and it can be seen that in each application different responses are reported. In agate processing via AWJ, the final quality of the piece depends on the properties of the initial damage region (IDR), such as width and depth. The present study has purpose to investigate the influence of the standoff distance, traverse speed, working pressure, and abrasive mass flow rate on the depth and width of the IDR when cutting agates through AWJ. A set of 80 samples were analyzed, and the measurement of the depth and width of the IDR was performed through three-dimensional scanning using X-ray computed microtomography (XCM). This technique allows assessing the IDR in an accurate and reliable way. The results showed that, within the investigated range of parameters, the width and depth of the IDR vary between 0.3 and 0.7 mm. Also, the IDR in the agate plates is strongly influenced by the standoff distance.

Modeling of cutting of stainless steel AISI 304 by abrasive water jet

Abrasive water jet (AWJ) has distinct advantages in machining stainless steel, titanium alloy and other metals because of its high machining ability and cold working characteristics. In this paper, the depth of cutting stainless steel AISI 304 by abrasive water jet was studied, so as to provide guidance for reasonable setting of process parameters. Firstly, the effect mechanism of main process parameters on cutting depth was analyzed. Then, the simulation model was built by the method of SPH coupled FEM to simulate the erosion process of abrasive water jet. Then, the material removal volume was studied from the micro and macro perspectives. Based on the essential equivalent relationship between the two aspects, the parametric model of cutting depth was deduced. Finally, the two models were compared and verified. The results show that the parametric model can be used to predict the cutting depth of AISI 304 and guide the setting of process parameters.

Study on the breaking process and damage characteristics of abrasive water jet impacting concrete based on acoustic emission

The breaking process and damage distribution characteristics of concrete are the theoretical basis for improving the quality and safety of concrete impacted by abrasive water jet (AWJ) technology. Therefore, the process of AWJ impacting concrete is monitored online based on acoustic emission (AE) technology in this paper. The results show that the AE signals of AWJ impacting concrete have two peaks in frequency domain, the low frequency signals are generated by AWJ and the high frequency signals are generated by concrete breaking. The autoregressive (AR) model is used to estimate the power spectrum of AE signals. The variations of AWJ signals and concrete crushing signals in the impact process are analyzed based on the power of AE signal defined by the area under the power spectral density (PSD) curve. Through monitoring the development process of erosion hole inside the transparent materials impacted by AWJ, it is verified that the power of the concrete crushing signals after the formation of the erosion hole can reflect the penetration rate well. In addition, the damage characteristics of concrete specimens impacted by AWJ are studied in this paper by measuring the transverse ultrasonic velocity of the specimens before and after impact.

Performance evaluation of the submerged abrasive water jet turning process for improving machinability of castamide

In this study, the submerged abrasive water jet turning (AWJT) system was used for improving machinability of castamide material and process parameters have been investigated comprehensively. Optimum parameters were determined as to minimize the surface roughness and maximize the material removal rate in the submerged turning process of castamide. 3-level traverse speed (TS), abrasive flow rate (AFR) and spindle speed (SS) were taken as the input parameters, and the experimental design was made as a full factorial design. The effect ratios of the input parameters were analyzed statistically by ANOVA and graphical methods, and their interactions were examined by 3D surface images. Optimum test condition was determined by TOPSIS and VIKOR methods. Experimental results were compared with conventional abrasive water jet process. In addition, regression equations were obtained for the explanation of the experimental results mathematically to show the relationships between the variables. According to the experimental results, submerged AWJT increased the surface roughness of castamide material by 15% compared to conventional AWJT and decreased the metal removal rate by 5.22%. ANOVA results showed that the traverse speed is the most effective parameter on the machinability of castamide. Traverse speed was found to be 83.11% effective on surface roughness and 85.56% on material removal rate. According to TOPSIS and VIKOR optimization results, 40 mm/min TS, 310 g /min AFR and 300 rpm SS values were determined as the optimum test conditions.

Integration of quality characteristics models as a software-based graphical interface for machining of AA6351 aluminum alloy using abrasive water jet process

In this paper, semi-empirical models of the performance characteristics, i.e., material removal rate, average surface roughness, kerf top width and taper angle in abrasive water jet machining (AWJM) of AA6351 aluminum alloy are reported. These models are developed using the dimensional analysis based on Buckingham ∏ theorem, and the proposed models for the considered performance parameters are analyzed both qualitatively and quantitatively using experimental data. Likewise, artificial feed forward neural network has been attempted to predict the considered performance parameters of AWJM process. For this purpose, different numbers of neurons have been tried at the hidden layer to obtain the best neural network. The validity of semi-empirical models and artificial neural network is verified using the experimental results. Furthermore, software prototype graphical user interface (GUI) is developed which allows user to interact with the models to predict the considered performance characteristics. The GUI is tested and validated through the experimental results. The results proved the functional capability and effectiveness of the GUI in predicting the performance characteristics.

Study on cutting speed and energy utilization rate in processing stainless steel with abrasive water jet

Cutting speed and energy utilization rate are two very important technical indexes for judging metal processing with abrasive water jet (AWJ). Cutting speed is related to the time benefit, while energy utilization rate is related to the economic benefit of AWJ processing. Based on theory of inelastic impact mechanics and hydrodynamics, the mathematical model of cutting speed and energy utilization rate in processing stainless steel with AWJ was established. And the discrete numerical analysis of the mathematical model was carried out. The effects of different jet parameters on cutting speed and energy utilization rate were explored. Cutting experiments were carried out to verify the model. The results show that with the increase of outlet pressure, the cutting speed increases linearly. With the increase of outlet pressure of 5 MPa, the cutting speed increases by 0.075 mm/s. When the outlet pressure increases from 10 to 46 MPa, the energy utilization rate decreases from 137 to 51.2 MJ/mm3. With the increase of mass fraction of abrasive, the cutting speed and energy utilization rate will increase first and then decrease. When the mass fraction increases from 5 to 25%, the cutting speed increases from 0.1504 to 0.2024 mm/s then decreases to 0.1308 mm/s, and the energy utilization rate increases from 35.13 to 43.93 MJ/mm3 then decreases to 23.73 MJ/mm3. The change of size of abrasive particle has no significant effect on cutting speed and energy utilization rate.

Experimental investigation into the effect of abrasive process parameters on the cutting performance for abrasive waterjet technology: a case study

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 Ra 2.1 μm under the flow rate of 130 g/min.