Papers by Keyword: Abrasive Waterjet

Abstract: Modern materials cutting operations are traditionally part of the research priorities and also in the production activities of ISIM Timișoara. In the last decade, within the institute, a special emphasis was placed on the development of the abrasive water jet cutting process as well as on implementing the research results obtained into industrial activities. The paper presents own achievements and contributions of ISIM to the development of the abrasive water jet cutting process in the following directions: cutting technologies for materials with different characteristics, innovative new patentable solutions regarding the cutting process respectively important modules in the composition of the water jet cutting equipment, ways to recycle used abrasive waste, solutions to streamline the process. The proposed solutions have been verified with good results in industrial applications, or have been proposed for analysis and development together with specialists in the field from important research units.

Abstract: This study evaluates the effect of process parameters on depth of penetration and surface roughness in abrasive waterjet (AWJ) cutting of copper. Full factorial experiments are carried out on trapezoidal blocks for each of the three abrasive particle sizes used. Experimental parameters - abrasive mass flow rate, water jet pressure and traverse speed are varied at three levels. Main effects and contributions of process parameters to depth of penetration and surface roughness is calculated. From the data, it is observed that, high abrasive mass flow rate, high water jet pressure and low traverse speed resulted in higher depth of penetration and a high abrasive mass flow rate, high water jet pressure and low traverse speed resulted in lesser R_a value. Using experimental data a statistical model for predicting depth of penetration & surface roughness is developed. Error between experimental and statistical values are compared to validate the statistical model. The maximum DOP of 49.32mm was observed at AMFR=405.4 g/min, P=300 MPa, TS=60 mm/min, MS=60 Mesh and minimum DOP of 4.27mm was observed at AMFR=200 g/min, P=100 MPa, TS=90 mm/min, MS=80 Mesh.

Abstract: Stainless Steels are possessing fabrication flexibility, high hardness, durability, low maintenance, high strength and resistance to heat and corrosion. This alloy steel is extensively used in various engineering applications. Some of the conventional machining techniques results in loss of original properties of stainless steel work material and makes it to behave like ordinary material within the machined surface. Machining of Stainless steels is more challenging due to its high alloying content. Problems such as application of huge coolant supply and poor chip breaking while machining, work hardening in work material, use of cutting tools with varying tool signature, results in enhanced production cost and time. Further, it is important to ensure that there is no machine tool-cutting tool vibration leading to edge chipping of cutting tool. To avoid all these problems, Abrasive water jet machining (AWJM) is used. This paper presents the machining capabilities of AWJ on Stainless Steel304. Influence of dynamic input parameters such as jet pressure, speed of traverse and abrasive flow rate on the depth of cut is investigated. An empirical model is proposed for depth of cut and an error analysis is done with measured and modeled values of depth of cut. It was found that traverse speed influences more than other parameters. SEM images indicated smooth surface at entrance and waviness at exit side. The model proposed predicts the depth of cut more or less accurately.

Abstract: Kerf profile generated by abrasive waterjet (AWJ) machining process has always been an interesting area as it dictates the quality of the part. However, due to the non-deterministic nature of the process, it is a challenging task to predict it. On the other hand, understanding and controlling the kerf profile in multi-layered structures (MLSs) is a further difficult task as various layers made of different materials respond to erosion in a different manner and results in a completely different kerf shape (barrel or x-shaped kerf profile) due to the material removal mechanisms dependency on the material property of the specific layers, jet divergence and position of specific layer. Therefore, it is important to understand and develop predictive models of resulting kerf profile in MLSs so that they can be used in controlling the accuracy of the resulting kerf which in turn dictates the final part accuracy. The attempts in this direction are very limited although some modeling efforts are reported in homogeneous materials (metals, ceramics). For the first time, an analytical model for predicting the kerf profile generated in MLS machining with AWJ was presented in this research work. Discretized form of Hashish model was used for determining depth of cut. The effect of jet divergence from the experimentally obtained values, upon passing through the upper layer has been considered. The developed predictive model was validated by the kerf shapes obtained from the experimental trials on metal-adhesive-rubber MLS. Kerf profiles obtained from the simulations have captured the resulted convergent-divergent (X-shaped) profile, while cutting metal-rubber laminate composite, effectively. Furthermore, the effectiveness of the proposed analytical model was demonstrated by generating the various kerf shapes generated at various jet traverse rates.

Abstract: Abrasive waterjet machining involves the impact of micro-particles at high or ultrahigh velocities. The material removal mechanism for ductile materials has been popularly accepted for over a half century as cutting wear and deformation wear caused by the component of impact force parallel and perpendicular to the target surface respectively. However, this definition of erosion mechanisms does not give an insight into the erosion process, but describes a surface phenomenon of the event. A computational study has been undertaken to reveal the underlying mechanisms of the material removal process. Based on the findings, the impact erosion mechanisms are re-defined as material destruction through (a) failures induced by inertia, (b) failure induced by elongation, and (c) failure induced by adiabatic shear bending. This new definition appears to better represent the physical process of material deformation and removal by loose micro-particle impacts at high and ultrahigh velocities.

Abstract: An experimental investigation of the hole machining performance for woven carbon-fiber reinforced PEEK (polyetheretherketone) sheets by an abrasive waterjet (AWJ) is presented. It is shown that AWJ machining can produce good quality holes if the cutting parameters are properly selected. Plausible trends of the hole quality with respect to the process parameters are discussed. Nozzle traverse speed and intended or programmed hole size are found to have a significant effect on the diameter error of the machined holes, hole roundness, and hole wall inclination angle, while water pressure and abrasive mass flow rate exhibit an insignificant effect. An increase in the traverse speed decreases the overall hole quality, while an increase in the programmed hole diameter decreases the hole diameter error and roundness error, but increases the hole wall inclination. There is not any clear trend of the hole wall surface roughness with respect to the process parameters. Moreover, high water pressures may result in hole defects, such as entrance surface chipping, delamination, internal cracking and fiber pull-out. It is found that the optimum process parameters are about 200 MPa water pressure, 2 mm/s nozzle traverse speed and 7.0 g/s abrasive mass flow rate. Recommendations are made for compensating for the hole size deviation and empirical models are fianlly developed for these hole characteristics.