Trends in the Development of Machinery and Associated Technology ” TMT 2008 , Istanbul , Turkey , 26-30 August , 2008 INFLUENCE OF FOCUSING TUBE WEAR ON THE CUT-SURFACE
The wear of the focusing tube is a very important feature of the abrasive water jet machining. Of all rejected focusing tubes, 85% are worn. Similary, the age of focusing tube influences the cut geometry and quality of machined surface. With regard to the stated, wearing of the focusing tube is subject of this paper. Focusing tube outlet diameter was measured as well as its influence on the surface quality.
Material removal in abrasive waterjet machining of metals Surface integrity and texture
An experimental study was conducted to determine the influence of material properties on the surface integrity and texture that results from abrasive waterjet (AWJ) machining of metals. A microstructure analysis, microhardness measurements, and profilometry were used in determining the depth of plastic deformation and surface texture that result from material removal. Models now available for dry abrasive erosion were adopted and found useful in understanding the influence of material properties on the hydrodynamic erosion process. It was found that the depth of subsurface plastic deformation is inversely proportional to a metals strength coefficient and extends the greatest depth near jet entry in the initial damage region (IDR). Furthermore, surface skewness in AWJ machining of metals increases with ductility and the corresponding critical strain for lip formation.
Abrasive Waterjet Machining of Polymer Matrix Composites – Cutting Performance, Erosive Process and Predictive Models
An investigation of the cutting performance and erosive process in abrasive waterjet (AWJ) machining of polymer matrix composites is presented. It shows that AWJ cutting can produce good quality kerf at high production rates if the cutting parameters are properly selected. Plausible trends of the cutting performance are discussed, as assessed by the various kerf geometry and quality measures, with respect to process parameters. The traverse speed, water pressure and abrasive flowrate are found to have a profound effect on the total depth of cut and kerf taper angle, while the first two variables also have a large effect on the kerf width. The study shows that the optimum jet forward impact angle in the cutting plane is about 80° which increases the total depth of cut only marginally, and has little effect on the other kerf characteristics. It is found that good quality kerf without delamination can be achieved if through cut is attained. A scanning electron microscopy (SEM) analysis of the cut surfaces reveals that the erosive process for the matrix material (resin) involves shearing and ploughing as well as intergranular cracking. Shearing or cutting is found to be the dominant process for cutting the fibres in the upper cutting region, but the fibres are mostly pulled out in the lower region. Mathematical models for the total depth of cut are finally developed and verified, together with empirical models for the other kerf geometrical features.