Study the parametric effect of abrasive water jet machining on surface roughness of Inconel 718 using RSM-BBD techniques

This paper presents an experimental investigation to ascertain the parametric impact of abrasive water jet machining on the surface quality of Inconel 718 material. Experiments were designed according to response surface methodology-box Behnken design by maintaining three levels of four process parameters—abrasive flow rate, water pressure, stand-off distance and traverse speed. The surface irregularity is measured during machining. The design expert software was used to establish an optimized mathematical model of process parameters for achieving the required surface roughness. Desirability function has also been used to optimize the process parameters. The confirmation experiments validate the reliability and capability of the developed model. Further, the surface characteristics were analyzed through scanning electron microscope images and energy-dispersive X-ray spectroscopy.     

水射流特种加工技术应用

高速水射流特种加工是利用具有很高动能的高速（超音速）水射流束来冲蚀材料，从而实现材料切削，属于高能束加工范畴，是一种可与激光、等离子体、电子束加工方法媲美的新型切割加工工具。水射流具有介质成本低、清洁、环境友好，而且对被加工材料无热损伤（被切割材料温度小于100℃）等优点，在许多材料的切割加工、表面处理中，水射流具有其独特的优越性。另一方面，水射流切割无（机械）接触，适应性好、切割表面精度高、切缝窄、材料损耗少、清洁无污染，配合数控执行机构可精确切割加工任意复杂形状工件。高速水射流尤其适用于高硬度、高脆性难加T材料、复合材料、钢筋混凝土、陶瓷、石材等的切割加工。     

Investigation on performance of abrasive water jet in machining hybrid composites

For 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 (R_a) and kerf taper (K_t). By generating a response surface model, the experimental values obtained for quality characteristics (R_a and K_t) 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.     

An investigation on cutting quality by adding polymer in abrasive water jet

ABSTRACT

An experimental investigation is presented to improve the cutting quality in abrasive water jet (AWJ) cutting of marble by an addition of polyacrylamide (PAM). Considering experimental data, the kerf widths have a remarkable change when the PAM concentration approaches to 400 ppm. The deviation between top and bottom kerf width reaches the minimal value when PAM concentration is equal to about 600 ppm. In addition, the surface topography analyses illustrate that an addition of PAM can broaden the cutting wear zone and make the cutting quality better. Furthermore, the effects of PAM on the surface roughness are assessed by a profilometer. It is eventually found that the surface roughness decreases initially and then increases greatly with the increase of the depth of cut. Additionally, the minimum surface roughness occurs when the PAM concentration is 600 ppm, which agrees well with the experimental result of kerf width. An increasing stand-off distance or traverse speed produces a higher surface roughness.     

AWJ machinability performance of CS/UPR composites with the effect of chemical treatment

This work focuses on the effect of chemical treatment of coconut sheath/unsaturated polyester (CS/UPR) composite on the performance of abrasive waterjet machining (AWJM). Two different chemical treatments, namely alkali (NaOH) and trichlorovinylsilane, were imposed on the CS fiber. Further, the induced compressive strength arising as a result of AWJM was studied along the radial and depth directions of the composite. Experimental results revealed significantly lower induced stress at all points compared to the ultimate stress of CS/UPR composites except the free-edge loading condition. The chemically treated composites also exhibited inconsistent results in the machining characteristics such as kerf taper angle (T_a) and surface roughness (R_a) under varying cutting conditions. However, no direct correlation was seen between interfacial adhesion and T_a and R_a of the cutting zone. The maximum decrease of 12% of T_a and 22% of R_a was found for silane-treated composites compared to the untreated ones. In addition, the composite failure mechanisms such as fiber pullout, fiber breakage, interfacial debonding, matrix failure, and voids were identified in the cutting surfaces through scanning electron microscopy analysis.     

Influence of nozzle design and process parameters on surface roughness of CFRP machined by abrasive jet

Carbon fiber reinforced polymer composites find extensive applications in the areas of automotive, aircraft and aerospace, medical sciences, and electronics. Their usage in automated engineering industry needs good quality in components and excellent surface finish. The aim of this research work is to make holes on carbon fiber reinforced polymer composite material using a newly designed nozzle with and without internal thread. Surface roughness (Ra) was calculated across the depth of the machined hole. The effect of air and abrasive mixture pressure (P), stand-off distance (L), nozzle diameter (D), and abrasive size (S) on surface roughness was carried out for two different nozzles. The experimental result showed offer of good surface finish on CFRP materials from the newly designed nozzle with internal thread.     

Cutting performance of glass-vinyl ester composite by abrasive water jet

Polymer matrix composite materials have been increasingly used in aerospace, defense, automotive and marine industries. In these fields, nontraditional machining method of abrasive water jet (AWJ) has been used significantly in order to form polymer matrix components. In this study, glass fiber reinforced vinyl ester composite plates have been investigated under various AWJ cutting parameters by using the Taguchi experimental design in detail. For Taguchi experimental design, experimental parameters of standoff distance, abrasive mass flow rate, traverse speed, pressure and material thickness were determined at three levels. Top kerf width and the surface roughness were investigated in order to understand the cutting performance. Finally, linear regression models were conducted and all performance parameters were examined using analysis of variance (ANOVA) and main effects plots. According to the overall test results, standoff distance was determined as the most effective one. The optimal parameter levels were obtained by the ‘main effects plots’, and finally, the predictive modeling was validated by performing the optimal combination of parameter levels.     

Study on three-body abrasive wear behavior of functionally graded Al/TiB2 composite using response surface methodology

Functionally graded LM13 Al/10?wt% TiB₂ metal matrix composite has successfully produced under centrifugal casting. Hollow cylindrical composite with dimensions 150?×?150?×?15?mm was produced under rotating centrifugal speed of 1100?rpm. Microstructural characteristics were studied on the composite surfaces at distance of 1, 5.5, and 10?mm from outer periphery of the casting, and the results revealed that surface at distance of 1?mm has presence of more reinforcement particles. An objective of this study was to characterize abrasion wear behavior at the composite surfaces using dry abrasion tester. Mathematical models were developed using response surface methodology to study the relationship of parameters such as load, speed, and distance from outer periphery with abrasion wear rate. Face centered Central Composite Design with 20 experiments was preferred for dry abrasion test. Adequacy of model was predicted through analysis of variance, and the significance test result shows that load has major impact on the wear rate. The optimized parametric condition to obtain minimum wear rate was found as load of 33?N, speed of 112?rpm, and distance of 1?mm from outer periphery. Scanning electron microscopy analysis done at worn out surface showed maximum wear resistance at the outer periphery.     

Study and evaluation of abrasive water jet turning process performance on AA5083

In this study, the effect of processing parameters on surface roughness and macro surface characteristics was analyzed during the machining of Ø30 mm and 300 mm aluminum alloy AA5083 abrasive water jets. As the processing parameters (up to 10 mm min⁻¹, 15 mm min⁻¹, 20 mm min⁻¹ and 25 mm min⁻¹), abrasive flow rate (50 g min⁻¹, 150 g min⁻¹, 250 g min⁻¹ and 350 g min⁻¹), the lathe chuck rotational speed (25 min⁻¹, 50 min⁻¹, 75 min⁻¹ and 100 min⁻¹) and the nozzle approach distance (2 mm, 5 mm, 8 mm and 11 mm) were used in experiments. In experimental studies, the pump pressure (360 MPa) was used as a constant, in the form of an abrasive Garnet (100 mesh), and the nozzle diameter as 0.76 mm. According to the findings, the best results in terms of surface roughness were obtained as a result of turning speed and abrasive flow rate. When the macro surface characteristics were examined, it was found that the lathe chuck rotational speed increased, the rate of nozzle progression was low, the rate of abrasive flow was high and the nozzle approach distance was lower and the smoother surfaces were obtained.     

Experimental investigation on unidirectional abrasive flow machining of trim die workpiece

Abrasive flow machining (AFM) processes are mainly used for deburring, polishing, and radiusing of surfaces and edges utilizing a viscoelastic abrasive media. The cutting edges of abrasive grits present in viscoelastic media play a significant role for removal of the burrs and irregularities present on the surface profile of the component. In industry, the AFM process is widely used form of edge and surface-conditioning with primary application in components with internal cavities inaccessible by traditional finishing tools. In this paper, a novel setup of unidirectional AFM process is proposed for finishing the industrial component. Response surface methodology has been used to plan and conduct the experiments, so that the influence of input process variables including finishing time, extrusion pressure, and viscosity of media can be observed on improvement in surface roughness (ΔR_a) and material removal. The finished surfaces of components are characterized for microstructure study using scanning electron microscopy and X-ray diffraction technique analysis.     

Multi-performance optimization of abrasive water jet machining of Inconel 617 using WPCA

Inconel 617 is a hard-to-machine material used for various high-temperature components like headers, pipes and turbine blades in ultra-supercritical power plants. This material necessitates nontraditional machining methods. The processing of these alloys using abrasive water jet machining (AWJM) needs attention. This paper details the multi-response optimization in the AWJM of Inconel 617 using weighted principal components analysis (WPCA). The significant process parameters are water pressure, abrasive flow volume, standoff distance and table feed. The performance characteristics are material removal rate (MRR), circularity, cylindricity, perpendicularity and parallelism. Multi-performance optimization is performed using the weighted principal component analysis method. Mean response tables are developed and plotted and the optimal factor levels for the best values of the objectives are reported. The developed technique shows flexibility as different responses with different weightages based on the product application could be tested and established.     

Post-impact damage characterization of hybrid configurations of jute/glass polyester laminates using acoustic emission and IR thermography

In this work, residual post-impact properties of two configurations of E-glass/jute hybrid laminates are characterized, both manufactured using a total fibre volume of 50 ± 2% (14 glass fibre layers + 4 jute fibre layers). T-laminates included a core obtained by multiple layers of jute between two E-glass fibre reinforced skins, whilst in Q-laminates single layers of jute fibres were intercalated at different levels between E-glass fibre reinforced layers. All laminates were impacted at five levels of energy, from 5 to 15 J, and then subjected to post-impact flexural tests.The results suggest that T hybrids perform better at low impact energies (up to 10 J), which do not damage significantly the laminate core. In contrast, Q hybrids are better suited to withstand extensive damage produced by higher impact energies (12.5 and 15 J), in that they allow a more effective redistribution of impact damage in the structure. This was confirmed by acoustic emission (AE) monitoring during flexural loading, which offered indications on the maximum stress laminates can undergo after impact damage. Pulse IR thermography yielded information on their mode of failure by visualizing impact-damaged areas.     

Correlation of roughness parameters Ra and Rq with an optical method of measuring them

A theoretically derived correlation between the roughness parameters R _a and R _q is given. An optical reflection method is proposed for measuring these parameters. An instrument is described that can implement this method. Translated from Izmeritel’naya Tekhnika, No. 4, pp. 16–19, April, 2009.     

Mechanical properties of cross-ply and quasi-isotropic composite laminates processed using aligned multi-walled carbon nanotube/epoxy prepreg

This study examined the processing and mechanical properties of cross-ply and quasi-isotropic composite laminates processed using aligned multi-walled carbon nanotube/epoxy prepreg sheets. Three kinds of CNT/epoxy laminates, ([0°/90°]s, [60°/0°/?60°]s, [0°/45°/90°/?45°]s) were successfully fabricated using aligned CNT/epoxy prepreg sheets. The CNT volume fraction was approximately 10%. No visible void or delamination was observed in composite laminates, and the thickness of each layer was almost equal to that of the prepreg. To evaluate the elastic moduli, E₁₁, E₂₂, and G₁₂, of each ply in the laminates, on-axis and off-axis tensile tests (0°, 45°, 90°) were conducted of aligned CNT/epoxy lamina specimens. The Young’s modulus of CNT/epoxy cross-ply and quasi-isotropic laminates agreed with the theoretical values, which were calculated using classical laminate theory and elastic moduli of CNT/epoxy lamina. The respective failure strains of [0°/90°]s, [60°/0°/?60°]s, and [0°/45°/90°/?45°]s laminates are 0.65, 0.92, 0.63%, which are higher than that of 0° composite lamina (0.5%). Results suggest that the failure strain of 0° layer in composite laminates is improved because of the other layers.     

电化学射流加工的电场仿真及实验研究

首先建立电化学射流加工去除模型,并基于电解液喷射流场建立三维电场仿真模型,采用ANSYS进行三维电场仿真,得到工件阳极表面的电场强度分布规律。研究表明,电压和喷射距离对电化学射流加工速度的影响很大,喷射角度、喷嘴直径和喷射压力对电化学射流加工的速度影响较小,电解液浓度(电导率)对电化学射流加工的电场强度没有影响,但对电化学射流加工的电流密度影响很大,电解液浓度对电化学射流加工速度的影响很大。然后进行不同工艺参数下电化学射流加工材料去除率实验,结果表明电压、喷射距离和电解液浓度对材料去除率的影响很大,与电场仿真结果一致。最后以SKD11模具钢为例进行NaNO3和NaCl电解液的电化学射流加工的表面形貌观察,结果表明,采用NaCl电解液的电化学加工后工件表面存在"微裂纹";而采用NaNO3电解液的电化学加工后工件表面不存在"微裂纹",加工过程中工件表面有Cr析出,加工区域氧化膜厚度是不均匀的。     

Development and characterization of PET/Fish Gelatin–nanoclay composite/LDPE laminate

A three‐layer laminate film was developed with the following structure: polyethylene terephthalate (PET)/fish gelatin (FG)–nanoclay composite/low‐density polyethylene (LDPE). The FG–nanoclay composite material functioned as the oxygen barrier layer and demonstrated comparable oxygen barrier properties when compared with a similar laminate utilizing ethylene vinyl alcohol as the barrier layer at a relative humidity (RH) of up to 50%. The introduction of nanometer‐sized filler clay into the FG matrix lowered the oxygen permeability (OP) because of the tortuosity effect of the clay particles. In addition, the FG–nanoclay composite film exhibited bond strengths similar to both LDPE and PET. The hydrophilic nature of FG significantly increases OP under high (>50%) RH conditions. However, this new FG laminate film could be a possible alternative for packaging designers desiring a more sustainable packaging material for low‐RH (<50%) applications. Copyright © 2009 John Wiley & Sons, Ltd.     

玉米秸秆纤维/脱硫石膏复合材料的性能

采用玉米秸秆纤维作为脱硫建筑石膏的增强材料, 通过力学性能测试实验研究了不同掺量秸秆纤维对石膏基复合材料力学性能的影响, 讨论了秸秆纤维的增强机制。结果表明, 秸秆纤维的掺量为5%时, 试样的抗折强度和抗压强度较空白样分别提高了92.31%和7.14%; 采用碱处理法、 聚丙烯酰胺化学包覆法、 丙烯酸化学包覆法对秸秆纤维进行表面改性, 通过力学性能测试实验和扫描电镜微观形貌观察研究了纤维表面改性对石膏基复合材料力学性能的影响。结果表明, 纤维表面改性改善了复合材料的界面结合状况, 进一步提高了复合材料的力学性能, 丙烯酸化学包覆改性可使脱硫建筑石膏复合材料的抗折强度较未改性玉米秸秆纤维/脱硫石膏复合材料提高55.71%, 抗压强度提高22.99%。      

Friction and wear behaviors of B4C/6061Al composite

The friction and wear behaviors of B₄C/6061Al composite were studied by considering the effect of sliding time, applied load, sliding velocity and heat treatment. The results show that, when the sliding time, applied load and sliding velocity reach critical values (namely 120 min, 30 N and 240 r min⁻¹, respectively), the mass loss and friction coefficient (COF) increase significantly. Severe delamination wear is the main wear mechanism after sliding for 120 min and under an applied load of 30 N. While fretting wear happens at a sliding velocity of 240 r min⁻¹. After solution-treated at 550 °C for 1 h and then aged at 180 °C for 15 h, the composite shows the highest wear resistance owing to the precipitation of β″ (Mg₂Si) phases in the matrix and the strong interface bonding between B₄C particles and the matrix alloy.     

Numerical optimization of hole making in GFRP composite using abrasive water jet machining process

Machining of composite materials for the production of bolt holes is essential in the assembly of the structural frames in many industrial applications of glass fiber-reinforced plastic (GFRP). Abrasive water jet cutting technology has been used in industry for such purposes. This technology has procured many overlapping applications and as the life of the joint in the assembled structure can be critically affected by the quality of the holes, so it is important for the industry to understand the application of the abrasive water jet cutting process on GFRP composite materials. The aim of the present work is to assess the influence of abrasive water jet machining parameters on the hole making process of woven-laminated GFRP material and to find the optimum values of the process parameters. Statistical approach was used to understand the effects of the predicted variables on the response variables. Analysis of variance was performed to isolate the effects of the parameters affecting the hole making in abrasive water jet cutting. The results show that the optimum values of cutting feed, fiber density, water jet pressure, standoff distance, and abrasive flow rate upon the response variables are 0.3 m/min, 0.82 g/cm³, 150 MPa, 2 mm, and 100 g/min, respectively.     

Synthesis of polishing fluid and novel approach for nanofinishing of copper using ball-end magnetorheological finishing process

Ball-end magnetorheological (MR) finishing process utilizes the magnetically controlled stiffened ball of an MR fluid for finishing purposes. Copper is a mechanically soft and chemically reactive material, so it is difficult to finish up to the nanometer-order level by traditional and most of the advanced finishing processes. In this research work, the problems associated with ball-end MR finishing of copper have been explored and a fluid composition suitable for the finishing of copper has been developed. A novel approach using two opposite magnetic poles has been used to enhance the magnetic flux density distribution between the tool tip and the copper workpiece surface. The same has been magnetically simulated and verified experimentally. The effect of fluid composition parameters has been analyzed by the statistical model developed by response surface. After 30 minutes of finishing time, a nano-finished surface with very few shallow scratches was achieved.