Experimental and numerical investigation of abrasive waterjet polishing technology

摘要

The objective of this investigation is the development of the abrasive waterjet (AWJ) based polishing technology. The result of the investigation will assist the implementation of AWJ polishing for manufacturing processes and procedures.;Experimental exploration of AWJ polishing involving processing of difficult-to-machine materials such as Alumina ceramic and stainless steel. Surface improvement due to this processing is evaluated by measuring the roughness of the generated surfaces and examining the microhardness and micro-topography of the surfaces using Scanning Electronic Microscopy (SEM). The surface roughness of 0.3 micron was obtained at samples of ceramic and metal alloys at a reasonable rate using 500-mesh garnet. No surface defects are induced.;The effect of various process variables on the topography of surfaces generated during AWJ polishing was evaluated. It is shown that the particles dimension and jet impact angle are two critical parameters controlling the process. The former determines the feasibility of AWJ polishing, and the later limits the extent of improvement in the surface topography. The force exerted on the sample surface is measured at various impingement angles. And, the effects of the tangential and normal component of the force on the surface topography is evaluated. The abrasive particles which constitute a machining tool in the AWJ polishing are collected after mixing and after impact, and analyzed using Laser Scanning Sizer and SEM. The acquired data reveal the details of the mechanism of AWJ polishing processes.;Numerical simulation of the motion of particles prior and after the impingement are conducted. Numerical solutions of the differential equations as applied to the two-phase turbulent jet flow are obtained using FIDAP package. The numerical prediction of jet velocity and force exerted on the target surface comply with the experimental results. The simulation of particles trajectories reveals existence of five distinctive patterns of particles motion which determine the surface topography.;This work pioneers the use of AWJ as a polishing tool and identifies the principal features of AWJ polishing and its use of computational packages for evaluation of the behavior of ultrahigh speed two-phase flows.