'Abrasive Flow Machining Essay\r'

'1. Introduction\r\n petulant flow machining (AFM) was firstly developed fifty old age ago by Extrude H unity Corporation, USA. By using the perspicuous viscoelastic material with thriving flowpower do of polymer and pettish grains, AFM abide be employ to shade, deburr and universal gas constant for the workpiece. There are three kinds of AFM: one-way AFM, two-way AFM and orbital AFM [1]. In this case to cause the cylinder heads, consider of two-way AFM is much to a greater extent widely use and its technology is more mature, we too choose the two-way AFM to do the show finishing. established of two-way flow shows in figure below.\r\n word miscellanea 1 principle of material removal apparatus in two-way AFM process [1] Prior to machining, smooth-spoken raspy allow for be put into the trim backrest medium cylinder, the designed fixture which secureing the workpiece go away be fixed between two cylinders. The upper medium, demean medium cylinder and fixture exi t form a confined space. later heat the all told system to works temperature, by forcing the lower diver (usually by hydraulic), the suave unsmooth will be pressed into the channel formed by clamp and workpiece, then flow into the upper medium cylinder. After the stroke of lower piston finished, the upper piston will crusade the liquid scratchy back into lower cylinder [2], an operating cycle will be finished.\r\nSee more: Beowulf experiment essay\r\n2. Three key elements of AFM\r\n1) Machine tool\r\n utilise to fasten the workpiece and fixture, and control the pressure applied on the workpiece, to adjust the degree of abrasive accuracy.\r\n2) Liquid abrasive\r\nLiquid abrasive is abrasive tool in the AFM, it should has following properties, a) Non-corroding and don’t adhere to the workpiece and human skin. b) Good adhesive properties between contrasting abrasive grains. c) Be able to maintain the viscoelasticity for a dogged age\r\nd) Non-volatile and non-deteri orate after a long time preservation. e) Strong cohesion.\r\nFor these properties, the conventional liquid abrasive is made from\r\nSemi-solid carrier which has viscoelasticity, flexibility and cutting property composite with abrasive grains. Different intrinsic viscosities of different carriers, different types and coat of abrasive grains can affect the last(a) tolerance and roughness [2]. The most frequently used abrasives are silicon carbide, carborundum, Cubic Boron Nitride(CBN), aluminum oxide, the size of grain vary from 0.005mm to 1.5mm. Abrasive with luxuriously viscosity is mainly used to polish the walls of workpiece and largish through-hole while low viscosity abrasive is generally for radiusing the edge and polishing the small through-hole.\r\n3) Fixture\r\nThe enjoyment of fixture,\r\na) Positioning and fixing the workpiece.\r\nb) Bearing clamping force for several(prenominal) workpiece.\r\nc) Constitute a channel for liquid abrasive with some machined surface o f workpiece in suitable size and section.\r\nd) Realizing simultaneous machine multiple workpiece in one device.\r\n3. Advantage of AFM,\r\nAbrasive flow machining has accuracy, stability and flexibility. It uses liquid abrasive to remove 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 improvement of AFM is the liquid abrasive can reach the positions which are not easily be machined by customs duty surface finish methods since the complexity of workpiece, polished surface evenly and in integrity, batch processing has the comparable result.\r\nThese characteristics improve the performance of part, extend the working life, bar the multifarious manual labour, and lower the intensity of labor. For example, when polish the intake-tube of vehicle by traditional process, the tube subscribe to be cut into half, then welding after polishing, but u sing the AFM, cut and welding can be avoided [3].\r\n4. Geometrical and thermal effects.\r\nViscosity 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.\r\n type 2 the machining effects of different viscosity of abrasive materials [5] Since cutting force is proportional to viscosity, so higher viscosity marrow stronger grinding ability, as a result abrasive with higher viscosity will get a better surface. In conclusion, temperature is a very great factor during the process. While the abrasive grains polish the surface, it will generate heat, enhancing the temperature as the figure 3 shown.\r\nFigure 3 Variation of rise in temperature of workpiece with name 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 as well as affects the result of surfa ce finishing. Many small through-holes comprise in the cylinder head, flow rate of abrasive is much bigger in these through-holes according to unsound mechanics, even these accelerations enhance grinding ability, but ascribable to shearing force generated by abrasive existence extrusion at narrow pass, it is evident that temperature will rise rapidly, lower the grinding ability. So geometric effect need to consider when design a cylinder head.\r\n1. Rhoades L.J., Kohut T.A., Reversible Unidirectional AFM, US apparent(a) number 5,070,652, Dec 10th, 1991. 2 Szulczynski, Hubert, Uhlmann, Eckart, MATERIAL remotion MECHANISMS IN peckish FLOW MACHINING\r\n3 Guizhen Song, theoretic ANALYSIS AND EXPERIMENTAL RESEARCH ON ABRASIVE FLOW MACHINING 4 Rajendra K. Jain, V. K. Jain. Specific energy and temperature finis in abrasive flow machining process[J]. International diary of Machine Tools & Manufacture, 2001(41):1689-1704 5 Tang Yong, chuck De-ming, Yang Gang, Ma chinability of Abrasive Flowing Machining. Journal of south china university of technology, 2001-9\r\n'