A study on the use of single mesh size abrasives in abrasive waterjet machining

This paper details the studies on the use of single mesh size garnet abrasives in abrasive waterjet machining for cutting aluminum. The influence of three different single mesh size abrasives, pressure, traverse rate, and abrasive flow rate; on depth of cut, top kerf width, bottom kerf width, kerf taper, and surface roughness are investigated. Experiments designed using standard L9 orthogonal array and the analysis of variance helped in the determination of highly significant, significant and weakly significant cutting parameters. Single mesh size abrasives are found to yield decreased surface roughness than multi mesh size abrasives. Based on these studies, response equations are developed to predict the target parameters. Using single mesh abrasives, a practitioner not only can cut faster but also achieve reduced surface roughness.     

Improved solutions for job shop scheduling problems through genetic algorithm with a different method of schedule deduction

This paper details the studies on the use of single mesh size garnet abrasives in abrasive waterjet machining for cutting aluminum. The influence of three different single mesh size abrasives, pressure, traverse rate, and abrasive flow rate; on depth of cut, top kerf width, bottom kerf width, kerf taper, and surface roughness are investigated. Experiments designed using standard L9 orthogonal array and the analysis of variance helped in the determination of highly significant, significant and weakly significant cutting parameters. Single mesh size abrasives are found to yield decreased surface roughness than multi mesh size abrasives. Based on these studies, response equations are developed to predict the target parameters. Using single mesh abrasives, a practitioner not only can cut faster but also achieve reduced surface roughness.     

Radial-mode abrasive waterjet turning of short carbon–fiber-reinforced plastics

An experimental study is carried out for single-pass radial-mode abrasive waterjet (AWJ) turning of a short carbon–fiber-reinforced polyetheretherketone (PEEK) specimen to understand the machining process and the effects of major process variables (feed speed, water pressure, abrasive mass flow rate, nozzle tilt angle, and rotational surface speed) on the major machining performance measures, that is, the depth of cut, material removal rate (MRR) and surface roughness. It is found that high water pressure, normal nozzle impact angle and high rotational speed with suitably selected feed speed and abrasive flow rate may be selected to achieve a high MRR without significantly compromising the surface roughness. Mathematical models for the three cutting performance measures are then developed for use in process control.     

Topographical anomaly on surfaces created by abrasive waterjet

In the present study, real topographic function and maximal depth of neglected initial zone were analytically developed to predict surface roughness on the top region of surfaces created by abrasive waterjet. An upper area of workpieces was analysed in details. Experimentally created surfaces were measured by HOMMEL TESTER T8000 and non-contact profilometer Micro Prof FRT. As an experimental material, stainless steel AISI 304, AISI 309 and aluminium with a thickness of 10?mm have been used. On the basis of analysis and interpretation of data obtained from the surface, a topography function Ra _d , which is necessary to be known for the subsequent prediction and control of abrasive waterjet cutting technology, is derived. In the framework of interpretation of measured values, relations among these parameters are systematically analysed and physico-mechanical and distributional principles governing these parameter are formulated newly. Results are very important for further estimation of analytical expression of the real topographic function for any surface created by abrasive waterjet cutting.     

Prediction of cutting force, tool wear and surface roughness of Al6061/SiC composite for end milling operations using RSM

The results of mathematical modeling and the experimental investigation on the machinability of aluminium (Al6061) silicon carbide particulate (SiCp) metal matrix composite (MMC) during end milling process is analyzed. The machining was difficult to cut the material because of its hardness and wear resistance due to its abrasive nature of reinforcement element. The influence of machining parameters such as spindle speed, feed rate, depth of cut and nose radius on the cutting force has been investigated. The influence of the length of machining on the tool wear and the machining parameters on the surface finish criteria have been determined through the response surface methodology (RSM) prediction model. The prediction model is also used to determine the combined effect of machining parameters on the cutting force, tool wear and surface roughness. The results of the model were compared with the experimental results and found to be good agreement with them. The results of prediction model help in the selection of process parameters to reduce the cutting force, tool wear and surface roughness, which ensures quality of milling processes.     

Optimization of machining parameters in the abrasive waterjet turning of alumina ceramic based on the response surface methodology

A study on the radial-mode abrasive waterjet turning (AWJT) of 96 % alumina ceramic is presented and discussed. An experimental investigation is carried out to explore the influence of process parameters (including water pressure, jet feed speed, abrasive mass flow rate, surface speed, and nozzle tilted angle) on the material removal rate (MRR) when turning 96 % alumina ceramic. The experiments are conducted on the basis of response surface methodology (RSM) and sequential approach using face-centered central composite design. The quadratic model of RSM associated with the sequential approximation optimization (SAO) method is used to find optimum values of process parameters in terms of surface roughness and MRR. The results show that the MRR is influenced principally by the water pressure P and the next is abrasive mass flow rate m _a . The optimization results show that the MRR can be improved without increasing the surface roughness when machining 96 % alumina ceramic in the radial-mode abrasive waterjet turning process.     

Parameter design for cut surface characteristics in abrasive waterjet cutting of Al/SiC/Al2O3 composite using grey theory based RSM

The abrasive mixed waterjet was successfully employed to cut many materials including austenitic steel, inconel and glass for a variety of industrial applications. The present work focusses on studying the surface roughness, striation zone and striation angle in Abrasive waterjet cutting (AWJC) of Al/SiC/Al₂O₃ composite. The water pressure, traverse speed, abrasive flow rate and stand-off distance were included as the dominant parameters in the study. The features of striation zone (length and angle) and surface roughness were observed as the responses for each of the cutting trials planned as per Taguchi’s L₁₈ orthogonal array. Parameter design was performed using the grey theory based response surface methodology (g-RSM) by following the method of simultaneous optimization to forecast the optimal cutting condition. All the studied parameters and their interactions were found to have a substantial effect on the observed responses. Significant improvements were observed in the responses obtained with the optimal parameter setting predicted by the g-RSM approach. The Atomic force microscopy (AFM) images and P-profile plots were also studied to observe the texture of the cut surface.     

Abrasive waterjet machining simulation by SPH method

Abrasive waterjet machining (AWJM) is a non-conventional process. The mechanism of material removing in AWJM for ductile materials and existing erosion models are reviewed in this paper. To overcome the difficulties of fluid–solid interaction and extra-large deformation problem using finite element method (FEM), the SPH-coupled FEM modeling for abrasive waterjet machining simulation is presented, in which the abrasive waterjet is modeled by SPH particles and the target material is modeled by FE. The two parts interact through contact algorithm. The creativity of this model is multi-materials SPH particles, which contain abrasive and water and mix together uniformly. To build the model, a randomized algorithm is proposed. The material model for the abrasive is first presented. Utilizing this model, abrasive waterjet penetrating the target materials with high velocity is simulated and the mechanism of erosion is depicted. The relationship between the depth of penetration and jet parameters, including water pressure and traverse speed, etc., are analyzed based on the simulation. The results agree with the experimental data well. It will be a benefit to understand the abrasive waterjet cutting mechanism and optimize the operating parameters.     

On the modelling of abrasive waterjet cutting

Abrasive waterjet cutting operates by the impingement of a high-velocity abrasive-laden waterjet against the workpiece. The jet is formed by mixing abrasive particles with high-velocity water in mixing tubes and is forced through a tiny sapphire orifice. The accelerated jet exiting the nozzle travels at more than twice the speed of sound and cuts as it passes through the workpiece.This cutting process is being developed as a net-shape and near-net-shape machining process for cutting many metals and hard-to-machine materials. The narrow kerf produced by the stream results in neither delimitation nor stresses along the cutting path. This new technology offers significant advantages over traditional processes for its ability to cut through most sections of dense or hard materials without the need for secondary machining, to produce contours, and to be integrated into computer-controlled systems.The abrasive waterjet cutting process involves a large number of process and material parameters which are related to the waterjet, the abrasive particles, and workpiece material. Those parameters are expected to effect the material removal rates and the depth of cut. The purpose of the present work is to propose a model which is capable of predicting the maximum depth of cut for different types of materials using different process parameters. A comparison of the results of the proposed model and the models reported in the literature is introduced along with a discussion of the limitations of those models.On leave from: Mechanical Engineering Department, Suez Canal University, Egypt.On leave from: Industrial Production Engineering Department, Mansoura University, Egypt.On leave from: Mechanical Power Engineering Department, Alexandria University, Egypt.     

磨料水射流切割陶瓷材料的加工表面质量研究

对磨料水射流切割氧化铝陶瓷的加工表面质量进行了试验研究,对磨料水射流切割陶瓷的切口结构形状进行了论述与分析,并分析了工艺参数对加工表面质量的影响。结果表明切口断面从上往下很明显地分成三部分:光滑区、波纹区和破碎区,光滑区的加工表面粗糙度随着水压力的增加、喷嘴横移速度和磨料粒度的减小而减小;靶距增加,表面粗糙度先减小,后增加。     

Topography and microstructure of the cutting surface machined with abrasive waterjet

Abrasive waterjet (AWJ) technology has been widely used for cutting materials in precision machining. The present paper reports the surface topography and microstructure of the cutting surfaces machined by AWJ. Four different kinds of ductile metallic materials were used for preparation of specimens. With the AWJ processing technique, smooth surfaces were easily obtained with a lower surface roughness about 2 to 3 μm. By comparing the microhardness of the specimens with the control surface sample obtained by wire electrodischarge machining, it is found that there is no heat-affected zone on the cutting surfaces machined by AWJ. By observing the surface morphology and microstructure, the features of friction and wear marks are revealed. The results show that a smooth cutting surface is more easily obtained on hard materials, while erosions on soft material surfaces are more serious. All scratches have a clear consistent direction, under the action of mechanical abrasive wear.     

Surface geometric parameters proposal for the advanced control of abrasive waterjet technology

The paper deals with a proposal for surface geometric parameters for advanced quality control of abrasive waterjet technology according to the results obtained by means of non-contact optical shadow method. The main emphasis is put on the analysis of results for defining the process for prediction of new surface creation generated by the set of the abrasive waterjet factors stream of abrasive waterjet, including its geometric parameters. By means of decomposition of measured surface profile according to the root mean square parameter, in four topographical different zones the initial zone, the smooth zone, the transition zone and the rough zone new possibilities for evaluation of the surface quality and optimizing the selected technological factors of the cutting process and their control through the proposed databank conceptual structure are presented. This report deals with the problems of selecting and proposing an acceptable method for surface quality control which is available for continuous measurement and production.     

Abrasive Waterjet Machining Simulation by Coupling Smoothed Particle Hydrodynamics / Finite Element Method

In dealing with abrasive waterjet machining(AWJM) simulation,most literatures apply finite element method(FEM) to build pure waterjet models or single abrasive particle erosion models.To overcome the mesh distortion caused by large deformation using FEM and to consider the effects of both water and abrasive,the smoothed particle hydrodynamics(SPH) coupled FEM modeling for AWJM simulation is presented,in which the abrasive waterjet is modeled by SPH particles and the target material is modeled by FEM.The two parts interact through contact algorithm.Utilizing this model,abrasive waterjet with high velocity penetrating the target materials is simulated and the mechanism of erosion is depicted.The relationships between the depth of penetration and jet parameters,including water pressure and traverse speed,etc,are analyzed based on the simulation.The simulation results agree well with the existed experimental data.The mixing multi-materials SPH particles,which contain abrasive and water,are adopted by means of the randomized algorithm and material model for the abrasive is presented.The study will not only provide a new powerful tool for the simulation of abrasive waterjet machining,but also be beneficial to understand its cutting mechanism and optimize the operating parameters.     

Effect of machining parameters on the milling process of 2.5D C/SiC ceramic matrix composites

Abstract

The C/SiC ceramic matrix composites are widely used for high-value components in the nuclear, aerospace and aircraft industries. The cutting mechanism of machining C/SiC ceramic matrix composites is one of the most challenging problems in composites application. Therefore, the effects of machining parameters on the machinability of milling 2.5D C/SiC ceramic matrix composites is are investigated in this article. The related milling experiments has been carried out based on the C/SiC ceramic matrix composites fixed in two different machining directions. For two different machining directions, the influences of spindle speed, feed rate and depth of cut on cutting forces and surface roughness are studied, and the chip formation mechanism is discussed further. It can be seen from the experiment results that the measured cutting forces of the machining direction B are greater than those of the in machining direction A under the same machining conditions. The machining parameters, which include spindle speed, feed rate, depth of cut and machining direction, have an important influence on the cutting force and surface roughness. This research provides an important guidance for improving the machining efficiency, controlling and optimizing the machined surface quality of C/SiC ceramic matrix composites in the milling process.     

Machining and simulation studies of bimetallic pistons

Light aluminium alloy piston is suitably reinforced at high load-bearing region with cast iron insert, and machining of such bimetallic material is more difficult with a single cutting tool material. Present study focuses on the orthogonal cutting of bimetallic material machining using cubic boron nitride as a cutting tool through finite element analysis. The effects of cutting parameters such as cutting velocity, feed rate and depth of cut on resultant cutting forces and the surface roughness were analysed. Those parameters yielding minimum cutting forces were identified as minimal cutting force parameters, so numerical simulation and experiments were carried out on these parameters. After machining, the intermediate bonding between metallic regions was studied using ultrasonic testing. Bimetallic machining is successfully simulated, and its potential is readily applied to an industrially important component.     

超声辅助微细磨料水射流加工陶瓷试验研究

针对陶瓷材料难加工的特性,提出了超声辅助微细磨料水射流加工技术。基于响应曲面法对工程陶瓷进行切槽试验,测量加工沟槽底部表面粗糙度,通过建立表面粗糙度预测模型,分析了系统压力、超声振幅及靶距对加工质量的影响规律。当系统压力为32.8MPa、振幅为16μm、靶距为10mm时,获得最低表面粗糙度为0.746μm。通过试验验证了该预测模型的准确性和有效性。     

Using the acoustic sound pressure level for quality prediction of surfaces created by abrasive waterjet

The paper deals with an innovative way of cutting materials by abrasive waterjet with a view to increase its quality. In the research work, we were concerned with the search for a relationship between surface roughness and noise in the abrasive waterjet cutting process. Innovation lies in the use of negative characteristic of the technology—noise, which is a carrier of information about the quality of cutting process. In this way, the noise can be positively used in the on-line control of the technological process. The final result is a project for control of the process of abrasive waterjet cutting of materials by means of feedback according to the on-line measurement of acoustic pressure level L _aeq (dB). Instantaneous information about the state of cut according to the instantaneous value of L _aeq amplitude allows the automatic regulation of traverse speed of cutting head v _p (mm.min^?1), which is, together with the pressure p (MPa), one of the most important technological factors of control of production technology from the point of view of economic indicators and qualitative indicators of a semiproduct. The proposed model has been experimentally verified and was simulated in Matlab.     

Experiment on carbon fiber–reinforced plastic cutting by abrasive waterjet with specific emphasis on surface morphology

In the machining of carbon fiber–reinforced plastic by abrasive waterjet, the surface morphology of the cutting front directly reflects the processin     

An investigation on use of colemanite powder as abrasive in abrasive waterjet cutting (AWJC)

In the present study, the cutting performance outputs (surface roughness, surface waviness and kerf taper angle) of colemanite powder as abrasive in abrasive waterjet cutting (AWJC) with varying traverse rate and abrasive flow rate were investigated experimentally. The performance outputs were compared to that of garnet which is in common use in industry as abrasive in AWJC industry. Al7075, marble, glass, Ti6Al4V and a composite material were selected as sample materials in the experiments. Furthermore, colemanite powder was mixed with garnet powder at certain proportions and the obtained surface characteristics were compared with those cut with pure garnet powder. It is found experimentally that in spite of higher amount of colemanite powder consumption with respect to garnet to perform the same cutting action, the colemanite powder could be an alternative powder for AWJC process.     

The performance Of DLC-coated and uncoated ultra-fine carbide tools in micromilling of Inconel 718

Coating is an important factor that affects cutting-tool performance. In particular, it directly affects surface quality and burr formation in the micro milling process. After the micromechanical machining process, surface quality is very hard to increase by a second process (grinding, etc.). In addition, in micromechanical machining, the cutting tool needs to have a good resistance to wear, owing to the fact that the cutting process is carried out at high speed. In this study, the machinability of Inconel 718 superalloy was investigated, using a Diamond Like Carbon (DLC) coated tool. The experimental tests were carried out in dry cutting conditions for different feed rates and depth of cuts. It was found that the dominant wear mechanism for all cutting parameters was identified to be abrasive and diffusive wear. Besides, a significantly Built Up Edge (BUE) formation was observed in uncoated tool. The results clearly show that DLC coating significantly decreased BUE. In addition, a smaller cutting force and better surface roughness were obtained with a DLC-coated tool. In conclusion, DLC coating can be used in micro milling of Inconel 718. It reduces the BUE and burr formation, improves surface roughness.