A New Strategy for Improving the Surface Quality of Ti6Al4V Machined by Abrasive Water Jet: Reverse Cutting with Variable Standoff Distances

Titanium alloys are widely used in important structures of aerospace vehicles, but the low thermal conductivity and high chemical activity make them difficult to process. As an untraditional machining technology, abrasive water jet (AWJ) has been proven to be an effective method for this kind of material. Aimed at further improving the cutting performance, reverse cutting with variable standoff distance (SOD) strategy was put forward, and experiments of titanium alloy Ti6Al4V machined by AWJ were conducted. The influence of SOD with different reverse cutting types on the kerf quality was studied to obtain the optimal SOD combinations. Ra, Sa and kerf taper were used to evaluate the quality of the machined surface. Moreover, the results of reverse cutting at the same speed and efficiency and single cutting at the constant SOD were compared and analyzed. It was found that the proposed strategy results in higher kerf quality in the aspect of surface roughness, compared to the single cutting. To be more specific, for the reverse trimming cutting, the improvements of Ra and Sa can reach up to 62.8% and 73.1% respectively under the condition of the SOD of the second cutting is 8mm. Furthermore, the kerf taper can be reduced 26.1% when the SOD of the second cutting is 2mm. With respect to the reverse deepening cutting, even the traverse speed of reverse cutting is set as twice as that of a single cutting, the kerf quality is still better. Additionally, when the SOD of the second cutting is 4mm, the improvements of Ra and Sa can reach up to 51.7% and 14.9%, respectively, and the kerf taper is reduced by 20.2%. This study provides a new method for improving the machined surface quality of hard materials, especially for Ti6Al4V.

Experimental Analysis of Kerf Taper Angle in Cutting Process of Sugar Palm Fiber Reinforced Unsaturated Polyester Composites with Laser Beam and Abrasive Water jet Cutting Technologies

In this research, the effect of processing input parameters on the kerf taper angle response of three various material thicknesses of sugar palm fiber reinforced unsaturated polyester composite was investigated as an output parameter from abrasive waterjet and laser beam cutting techniques. The main purpose of the study is to obtain data that includes the optimum input parameters in cutting the composite utilizing these two unconventional techniques to avoid some defects that arise when using traditional cutting methods for cutting the composites, and then make a comparison to determine which is the most appropriate technique regarding the kerf taper angle response that is desired to be reduced. In the laser beam cutting process, traverse speed, laser power, and assist gas pressure were selected as the variable input parameters to optimize the kerf taper angle. While the water pressure, traverse speed, and stand-off-distance were the input variable parameters in the case of waterjet cutting process, with fixing of all the other input parameters in both cutting techniques. The levels of the input parameters that provide the optimal response of the kerf taper angle were determined using Taguchi’s approach, and the significance of input parameters was determined by computing the max–min variance of the average of the signal to-noise ratio (S/N) for each parameter. The contribution of each input processing parameter to the effects on kerf taper angle was determined using analysis of variation (ANOVA). Compared with the results that were extrapolated in the previous studies, both processes achieved acceptable results in terms of the response of the kerf taper angle, noting that the average values produced from the laser cutting process are much lower than those resulting from the waterjet cutting process, which gives an advantage to the laser cutting technique.

Performance of Cutting Parameters for Surface Excellence on 304 Stainless Steel Using Abrasive Water Jet Technique

Advanced machining techniques are extensively being adopted for machining of high strength materials such as stainless steels. However, these materials are difficult to be machined out due to properties such as high work hardening rate and low thermal conductivity, work hardening and poor machinability. The manufacturing requirements such as production of high precision and surface finished components has led the researchers to study abrasive water jet (AWJ) machining and its applications in industrial sectors. As the AWJ is multi-operational and can produce high precision components. The carried-out work mainly intended to involve technical parameters such as water pressure, cutting speed, abrasive flow. These parameters were analyzed with respect to kerf taper and surface roughness on 304 stainless steel. Two critical variables namely cutting speed and outlet pressure were varied from 100 to 200 mm /min and 100 to 200 MPa, respectively. In additional based on the setup flow rate was altered from 360 to 540 g/min. The experimental results indicate kerf taper and surface roughness were strongly deflect by varying cutting rate, water pressure, and flow rate. Optimization of process parameter was performed by adopting response surface methodology as well as central composite design method. Finally, mathematical models and set of contour graphs for tested surface quality along the kerf taper angle was carried out using ANOVA analysis.

Impacts of Traverse Speed and Material Thickness on Abrasive Waterjet Contour Cutting of Austenitic Stainless Steel AISI 304L

Abrasive water jet machining is a proficient alternative for cutting difficult-to-machine materials with complex geometries, such as austenitic stainless steel 304L (AISI304L). However, due to differences in machining responses for varied material conditions, the abrasive waterjet machining experiences challenges including kerf geometric inaccuracy and low material removal rate. In this study, an abrasive waterjet machining is employed to perform contour cutting of different profiles to investigate the impacts of traverse speed and material thickness in achieving lower kerf taper angle and higher material removal rate. Based on experimental investigation, a trend of decreasing the level of traverse speed and material thickness that results in minimum kerf taper angle values of 0.825° for machining curvature profile and 0.916° for line profiles has been observed. In addition, higher traverse speed and material thickness achieved higher material removal rate in cutting different curvature radii and lengths in line profiles with obtained values of 769.50 mm3/min and 751.5 mm3/min, accordingly. The analysis of variance revealed that material thickness had a significant impact on kerf taper angle and material removal rate, contributing within the range of 69–91% and 62–69%, respectively. In contrast, traverse speed was the least factor measuring within the range of 5–18% for kerf taper angle and 27–36% for material removal rate.

Multi-objective Optimization of Kerf-taper and Surface-roughness Quality Characteristics for Cutting-operation On Coir and Carbon Fibre Reinforced Epoxy Hybrid Polymeric Composites During CO2-Pulsed Laser-cutting Using RSM

Current research focuses on optimizing various quality characteristics for kerf geometry generated through laser cutting of Coir fibre/carbon fibre/epoxy resin hybrid composite adjacent to straight cut profile employing pulsed CO2 laser system. The Kerf taper (KT) and the Surface roughness (SR) are the main quality parameters discussed. Dependent on significant process parameters, namely gas pressure, cutting speed, pulse frequency and pulse width predictive models were developed. In accordance with Taguchi's L9 orthogonal array (OA), the cutting trials are designed. Process-parametric optimization was performed using Response Surface Methodology (RSM). Furthermore, experiments were performed to obtain experimental data for the analysis of cut quality features. The impact of the input variables on the response characteristics is also explored. The morphological characterizations have been performed to analysis the effect of machining-variables and cut-quality for the top and bottom kerf widths with various laser cutting variables in the pulse laser-cutting of Coir-fibre/carbon-fibre/epoxy-resin hybrid composite. For SR and KT, the developed second order surface response model was found very successful. The optimal levels of cutting variables for KT are established at Gas pressure-6 N/mm2, pulse width-2.04 ms, cutting speed-8.01 mm/s, pulse frequency-15 Hz, for sample A1, Gas pressure-5.47 N/mm2, pulse width-2.5 ms, cutting speed-8.81 mm/s, pulse frequency-8.43 Hz, for sample A2, Gas pressure-3.85 N/mm2, pulse width-1.5 ms, cutting speed-9.06 mm/s, pulse frequency-5 Hz, for sample A3 additionally for SR Gas pressure-2 N/mm2, pulse width-1.5 ms, cutting speed-7 mm/s, pulse frequency-5 Hz, for sample A1, Gaspressure-2.36 N/mm2, pulse width-1.5 ms, cutting speed-7 mm/s, pulse frequency-15 Hz, for sample A2, Gaspressure-6 N/mm2, pulse width-1.5 ms, cutting speed-11 mm/s, pulse frequency-8.73 Hz, for sample A3. Regression results and linear and square impact of laser cutting variables have been revealed to be important to validate the model.

Impacts of traverse speed and material thickness in abrasive waterjet contour cutting of Austenitic stainless steel AISI 304L

Austenitic stainless steel 304L (AISI304L), of varied thickness, is widely used in the fabrication industry and in many cases, it requires contour machining for achieving intricate profiles. Abrasive water jet machine is a proficient alternative for machining difficult-to-cut, reflective, conductive, and heat-sensitive materials such as austenitic stainless steel with complex geometries. However, due to differences in machining responses for varied material conditions, the abrasive waterjet machine experiences challenges such as kerf geometric inaccuracy and low material removal rate. In this study, an abrasive waterjet machine is employed to perform contour cutting of different profiles to investigate the impacts of traverse speed and material thickness in achieving a lower kerf taper angle and higher material removal rate. Experimental results show that all profiles encountered a similar trend of obtaining higher kerf taper angle and material removal rate as traverse speed increased. Analysis of variance revealed that material thickness denotes a more significant impact to kerf taper angle and material removal rate with a contribution within the range of 69%-91% and 62-69% respectively; whereas traverse speed indicates the least contributing factor within the range of 5%-18% in kerf taper angle and 27%-36% for material removal rate.

Parametric optimization of laser drilling of microwave-processed kenaf/HDPE composite

The present work focused on the investigation of hole quality characteristics in laser-drilled kenaf/high-density polyethylene (HDPE) composites. Microwave-assisted compression molding was used to fabricate kenaf/HDPE composite with 20 wt% of the kenaf fiber reinforcement. The two input parameters pertaining to the experimentation were laser power and cutting speed. Kerf taper angle, heat-affected zone (HAZ), and surface roughness were investigated to evaluate the surface quality and accuracy of the holes generated through laser drilling on composite specimens. The assessment of HAZ was performed qualitatively through image analysis on scanning electron micrographs. Additionally, the effect of composite thickness on laser drilling was also investigated for 3-, 6.7-, and 10-mm composite specimens. The central composite design was used to plan the experiments. The kenaf/HDPE composite drilled at power 120 W and speed 2 mm/s shows a minimum kerf taper angle and surface roughness of 0.056° and 3.83 ± 0.19 µm, respectively. Regression model was obtained for the establishment of relation between input variable parameters and responses. Experimental results and predicted model results exhibited good agreement with each other as they provide error less than 5.35%. The analysis of variance was carried out to obtain the significance of the model chosen for optimization of the output values, that is, surface roughness and kerf taper.

AWJM Performance Measurement of Sandwich Composites

Sandwich composites, wherein the skin and core fulfills the requirement of different properties, like in foam sandwich structure, foam is providing damping and skin provides rigidity to the structure. In this work a sandwich panels with foam core and glass/polyester skin is fabricated by vacuum infusion technique. Abrasive water-jet drilling of these materials is performed to study the effect of standoff distance (SOD), Water Jet Pressure (JP) and Traverse Rate (TR) on kerf taper and surface roughness and Material Removal Rate (MRR). The experiment is designed using Taguchi’s L9 orthogonal array. The ANOVA is done to study the influence of input parameters on output. It is found that SOD is the most influencing parameter on the kerf taper and surface roughness..