Performance Of Abrasive Waterjet Research Articles

Study on abrasive particle impact modeling and cutting mechanism

AbstractAbrasive water jet impact is widely applied in processing, oil fracturing, coal mining, rock crushing, and other engineering fields. The influence of abrasive particles on cutting performance is one of the main characteristics of this technology, which is different from pure fluid cutting. Therefore, as for improving the cutting performance of abrasive water jet, studying the cutting mechanism of abrasive water jet, and clarifying the mapping relationship between particle parameters and cutting, it is of great theoretical and practical significance to clarify the impact failure mechanism and material removal mechanism of abrasive particles in the process of high‐speed impact. In order to study the effect of abrasive particles on cutting performance, irregular abrasive particles are simplified to angular particles and circular particles in this paper. The impact shooting process of particles in abrasive jet cutting is numerically simulated by using smoothed particle hydrodynamics (SPH) method, and the target impact experiments are carried out. The fracture processes of ductile materials and brittle targets impacted by different shapes of particles are studied. The results are showed as follows. Firstly, the SPH numerical model has high accuracy and successfully reproduces the collision process of particles in the process of abrasive jet cutting, including the deformation mechanisms such as plowing, cracking and crushing of the target, and the error of the dent curve formed by the collision is less than 0.5 mm. Secondly, the impact mechanism of angular and circular particles is different for targets with different material properties. For ductile materials, the process of material accumulating to failure value is slow, mainly by the way of accumulation removal. And for brittle materials, it mainly produces plastic deformation and failure, without obvious material accumulation and extrusion area. Thirdly, different impact angles of particles have great influence on material removal.

Multi-objective Soft Computing Approaches to Evaluate the Performance of Abrasive Water Jet drilling Parameters on Die Steel

In the current manufacturing methods, improvement in process performance will be resulting in huge benefits to the industries. For the improvement in part or product quality, the machining process must be operating with the optimal parameters, and thus, quality attributes can be produced. It applies to one of the modern machining techniques such as abrasive water jet (AWJ) as the use of this technique is growing rapidly in manufacturing industries for needful applications. Therefore, the present work is proposed to find the optimal level of AWJ parameters such as water jet pressure, stand-off distance, abrasive mass flow rate for drilling die steel with the simultaneous minimization of drilled hole features such as surface roughness, circularity, and cylindricity by using an unusual metaheuristic technique, namely harmony search algorithm (HSA). In addition, taguchi grey relational analysis (TGRA) was performed and their results were compared with the HSA technique. The multiple linear regression models were developed for each response, and the same were used in HSA to determine the optimum parameters for the minimization of responses where the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) method was employed to convert the multi-objectives into single objective. In this study, the efficacy of HSA technique was demonstrated with the hole features of die steel. The results proved that the HSA technique had outperformed the TGRA based on the overall improvement in AWJ drilling performance on die steel, and the predicted process attributes such as surface roughness of 1.53625 μm, circularity of 0.04370 mm, and cylindricity of 0.02459 mm were obtained at water jet pressure of 275.4 MPa, stand-off distance of 3.96 mm, and abrasive flow rate as 0.25 kg/min. Also, the percentage deviation error (< 6%) of the predicted hole features of HSA is acceptable and analogous to the experimental results. Hence, it is confirmed that a new metaheuristic algorithm, namely HSA was found suitable for the AWJ drilling process.

Study on perforation performance of abrasive water jet enhanced by percussive drilling

Geothermal energy is abundant and has a high economic development value. Perforation would need to be utilized to establish fluid channels between the borehole and geothermal reservoirs. In the present paper, it is proposed to use percussive drilling to create impact cracks near the borehole to improve abrasive water jet (AWJ) perforation performance. Two groups of the specimen were used for experiments. One was the specimen near the borehole after conventional rotary drilling (G1), the other was the specimen near the borehole after percussive drilling (G2). The optimal parameters of AWJ perforation assisted by percussive drilling were obtained. Through evaluation of AWJ perforation performance, it was found that the perforation depth, diameter and volume of G2 were 1.5 times, 1.3 times and 2 times of the G1, respectively. Besides, there were many internal cracks in G2, which interweave with each other and form a crack network. The results indicated that the impact cracks could change the mechanical properties of the granite near the borehole, then reduce the difficulty of AWJ perforation and improve the perforation performance. All the above merits can provide important technical support for reducing the fracturing pressure, increasing fluid flow and enhancing heat exchange efficiency between geothermal reservoir and borehole.

Fuzzy prediction of AWJ turbulence characteristics by using typical multi-phase flow models

ABSTRACTFor the purpose of improving the working performance of AWJ (Abrasive waterjet) grinding in actual machining, and revealing the unknown influence mechanism of waterjet machining prediction, this research conducted a theoretical and experimental investigation concerning with the influences caused by multi- phase flow models, on the fuzzy prediction of turbulence characteristics. First, typical flow models describing the abrasive waterjet were presented and enunciated; Second, a series of turbulence characteristics were defined to quantitatively demonstrate the waterjet flow, which are responsible for the actual performances of AWJ grinding in the contact zone; Then a new fuzzy prediction system equipped with logic protocols was established and introduced to predict turbulence characteristics based upon the machining parameters by employing different flow models, therefore a set of quantified prediction results generated from the CFD (Computational Fluid Dynamics) simulation, orthogonal experiments and actual measurements can be obtained and distinguished systematically. Through a detailed performance analysis with benchmark indexes and prediction comparisons, the theoretical superiorities and specific applications of these flow models were fully discussed and then an integrated conclusion assessing their inherent influence mechanism was acquired. Based on these innovative achievements, the instantaneous machining inspection or parameter optimization in AWJ grinding process can be facilitated, simultaneously the new research ideas aimed at waterjet monitoring or grinding improvements can be presented as well.

Investigation on performance of abrasive water jet in machining hybrid composites

ABSTRACTFor machining of composites, abrasive water jet machining is widely employed. For assembly of the machine tool structure, production of slots is essential. In this paper, abrasive water jet machining of composite laminates was experimentally investigated for various cutting parameters in terms of average surface roughness (Ra) and kerf taper (Kt). By generating a response surface model, the experimental values obtained for quality characteristics (Ra and Kt) were empirically related to cutting parameters. The effects of cutting parameters on quality characteristics were analyzed by utilizing empirical models and also optimized within the tested range based on desirability approach. The optimum parameter levels were also validated by confirmation test. From this investigation, it is evident that for obtaining a minimum kerf taper, traverse speed, water pressure, and abrasive mass flow rate are significant parameters and for obtaining less surface roughness traverse speed is the significant parameter.

102 水溶性粒子を用いたアブレシブウォータジェットの加工性能の評価及び粒子供給方法の開発(フェロー賞対象講演I)

102 水溶性粒子を用いたアブレシブウォータジェットの加工性能の評価及び粒子供給方法の開発(フェロー賞対象講演I)

Characteristics of abrasive waterjet cut-edges and the affect on formability and fatigue performance of high strength steels

The characteristic surface properties and internal workpiece transformations formed during the Abrasive Waterjet (AWJ) cutting process influences the formability and fatigue performance of steel cut-edges. This relatively established cutting technology is used in industry to generate specialist low production components, which may undergo continual loading cycles under operational service conditions. The fatigue performance of AWJ cut-edges can be critical since individual notch defects produced by the cutting process can act as initiation sites from where fatigue cracks can propagate. Due to the increased sensitivity of high strength structural steels to cut-edge fatigue, AWJ cut-edge defects have an ever more significant influence on fatigue performance. The relationship between the traverse cutting speed and the influence on the resulting properties of the cut-edge has been the critical area of investigation. The affects of traverse cutting speed on the surface roughness properties and cut-edge hardening through a process of plastic deformation of grains in the near edge region were observed to be influenced by the traverse cutting speed. It is these characteristic factors that were determined to influence the cut-edge ductility and fatigue performance of steel components. It is a combination of the AWJ properties that produces cut-edges, which are positive for the Hole Expansion Capacity (HEC) but negative for stress life and cyclic stress strain life fatigue performance of AWJ cut high strength steels.

Optimum abrasive flow rate modelling for titanium alloy cutting using abrasive water jet

Abrasive water jet (AWJ) cutting systems are extensively used in industry, thus optimisation of the process parameters that determine efficiency, economy and quality of the process is becoming more and more important. However, being a complicated cutting system, the performance of AWJ is characterised by a large number of process parameters, which include water pressure, orifice diameter, traverse rate, standoff distance, impact angle, focusing tube diameter, abrasive flow rate (AFR), etc. Therefore, optimising the process parameters involves a number of challenging efforts. This paper concentrates on investigating the optimum AFR at the highest cutting speed under different water pressures, orifice diameters and focusing tube diameters. Based on a theoretical derivation combined with an experimental study, an empirical model for calculating the optimum AFR is created.

Maximum depth of cut and mechanics of erosion in AWJ oscillation cutting of ductile materials

The nozzle oscillation technique was shown recently to enhance the performance of Abrasive Water Jet (AWJ) cutting. However, the fundamental reasons behind these process improvements have not been well established. In addition, presently available models of AWJ cutting, which are used for predicting depth of cut and, in some cases, surface quality are not capable of tackling the nozzle oscillation technique. The paper presents a semi-empirical model that can be used for predicting the maximum depth of cut in both oscillation and normal cutting processes. The model was constructed by integrating the results of a visualisation and parametric experimental study of the AWJ cutting process that compares the nozzle oscillation technique with conventional AWJ cutting to the theoretical potential of the cutting process. The experimental results for ductile materials processing show that by oscillating the nozzle during cutting at relatively small angle and high frequencies of oscillation, the efficiency of the erosion process is appreciably increased. At the optimum, oscillation parameter settings, about 30% improvements in performance were obtained for oscillation cutting of mild steel compared to normal cutting samples, while the level of improvement that was found for aluminium samples were about 20%. Outside this optimum range, the process performance for nozzle oscillation was found to be worse than normal cutting.