Abrasive Flow Machining Essay

1. IntroductionAbrasive run away machining (AFM) was firstly developed liter years ago by Extrude H i Corporation, USA. By exploitation the smooth viscoelastic satisfying with easy f economic crisisability made of polymer and peckish grains, AFM cigarette be utilize to polish, deburr and radius for the workpiece. There are three kinds of AFM unidirectional AFM, two-part AFM and orbital AFM 1. In this case to manufacture the piston chamber heads, train of two-way AFM is much much widely used and its technology is more than mature, we similarly choose the two-way AFM to do the step up finishing. Schematic of two-way flow shows in figure below.Figure 1 principle of material removal mechanism in two-way AFM process 1 Prior to machining, liquified abrasive will be put into the press down medium cylinder, the designed fixture which clamping the workpiece will be fixed between two cylinders. The f number medium, lower medium cylinder and fixture will form a confined space . After heat the whole frame to working temperature, by forcing the lower piston (usually by hydraulic), the liquid abrasive will be pressed into the channel formed by clamp and workpiece, then flow into the pep pill medium cylinder. After the stroke of lower piston finished, the upper piston will force the liquid abrasive back into lower cylinder 2, an operating cycle will be finished.See more Beowulf essay essay2. Three key elements of AFM1) Machine beam of light hire to fasten the workpiece and fixture, and control the pressure applied on the workpiece, to adjust the class of abrasive accuracy.2) Liquid AbrasiveLiquid abrasive is abrasive tool in the AFM, it should has following properties, a) Non-corroding and dont adhere to the workpiece and human skin. b) salutary adhesive properties between antithetic abrasive grains. c) Be able to arrest the viscoelasticity for a long clock timed) Non-volatile and non-deteriorate after a long time preservation. e) Strong cohesion.For these properties, the conventional liquid abrasive is made fromSemi-solid carrier which has viscoelasticity, flexibility and film editingting property mixed with abrasive grains. Different intrinsic viscosities of different carriers, different types and size of abrasive grains can affect the final tolerance and roughness 2. The most frequently used abrasives are silicon carbide, carborundum, cubical Boron Nitride(CBN), aluminum oxide, the size of grain vary from 0.005mm to 1.5mm. Abrasive with senior high school viscosity is mainly used to polish the walls of workpiece and large through-hole while low viscosity abrasive is primarily for radiusing the edge and polishing the small through-hole.3) securenessThe function of fixture,a) Positioning and fixing the workpiece.b) Bearing clamping force for some workpiece.c) make believe a channel for liquid abrasive with some machined surface of workpiece in suitable size and section.d) Realizing simultaneous machine multiple workpiece in one device.3. Advantage of AFM,Abrasive flow machining has accuracy, stability and flexibility. It uses liquid abrasive to take up the metal material infinitesimally, deburr and radius the internal intersections of workpiece. At present, AFM is widely used in automotive industry and other manufacturing. The fundamental advantage of AFM is the liquid abrasive can reach the positions which are not easily be machined by tradition surface finish methods since the complexity of workpiece, polished surface evenly and in integrity, batch processing has the same result.These characteristics improve the motion of part, extend the working life, avoid the multifarious manual labour, and lower the vehemence of labor. For example, when polish the intake-tube of vehicle by traditional process, the tube need to be cut into half, then welding after polishing, but using the AFM, cut and welding can be avoided 3.4. Geometrical and thermal effects.Viscosity of liquid abrasive will decrease when the working temperature enhances 3, and working ability of abrasive depends on its viscosity as the figure 2 shown.Figure 2 the machining effects of different viscosity of abrasive materials 5 Since cutting force is proportional to viscosity, so higher viscosity means stronger grinding ability, as a result abrasive with higher viscosity will get a better surface. In conclusion, temperature is a very important factor during the process. turn the abrasive grains polish the surface, it will generate heat, enhancing the temperature as the figure 3 shown.Figure 3 Variation of establish in temperature of workpiece with number of cycles 4 The rise of temperature will make the working ability reduce. So cooling system is need during the process to ensure the best machined surface. Geometry of cylinder head also affects the result of surface finishing. Many small through-holes exist in the cylinder head, flow rate of abrasive is much bigger in these through-holes agree to fluid mechanics , even these accelerations enhance grinding ability, but due to prune force generated by abrasive being extrusion at compact pass, it is evident that temperature will rise rapidly, lower the grinding ability. So geometric effect need to consider when design a cylinder head.1. Rhoades L.J., Kohut T.A., rechargeable Unidirectional AFM, US patent number 5,070,652, Dec 10th, 1991. 2 Szulczynski, Hubert, Uhlmann, Eckart, substantial REMOVAL MECHANISMS IN ABRASIVE FLOW MACHINING3 Guizhen Song, THEORETICAL compendium AND EXPERIMENTAL RESEARCH ON ABRASIVE FLOW MACHINING 4 Rajendra K. Jain, V. K. Jain. special(prenominal) energy and temperature determination in abrasive flow machining processJ. International journal of Machine Tools & Manufacture, 2001(41)1689-1704 5 Tang Yong, Zhou De-ming, Yang Gang, Machinability of Abrasive Flowing Machining. journal of south china university of technology, 2001-9