27-10-2012, 06:49 PM
i want to ppt of non conventional machining methods[/align]
27-10-2012, 06:49 PM
i want to ppt of non conventional machining methods[/align]
27-05-2013, 12:05 PM
PRESENTATION ON NON CONVENTIONAL MACHINING
CONVENTIONAL MACHINING.ppt (Size: 1.94 MB / Downloads: 57) Grinding Grinding uses abrasives which are small, hard particles having sharp edges (but irregular shapes). Small amount of metal can be removed as tiny metal chips Machine heat treated parts Ceramic, glass Weld beads Semi-machined die surfaces Temperature rise Very high temperature (3000oF) Chips carry away the heat Larger fraction of heat is conducted into workpiece Effect of temp rise More pronounced than metal cutting Excessive temp rise caused by grinding can temper or soften hardened metal NONTRADITIONAL (OR) UNCONVENTIONAL MACHINING The requirements that lead to the development of nontraditional machining. Very high hardness and strength of the material. (above 400 HB.) The work piece is too flexible or slender to support the cutting or grinding forces. The shape of the part is complex, such as internal and external profiles, or small diameter holes. Surface finish or tolerance better than those obtainable conventional process. Temperature rise or residual stress in the work piece are undesirable. Electrochemical Machining Reverse of electroplating An electrolyte acts as a current carrier and high electrolyte movement in the tool-work-piece gap washes metal ions away from the work piece (anode) before they have a chance to plate on to the tool (cathode). Tool – generally made of bronze, copper, brass or stainless steel. Electrolyte – salt solutions like sodium chloride or sodium nitrate mixed in water. Power – DC supply of 5-25 V. Wire EDM This process is similar to contour cutting with a band saw. a slow moving wire travels along a prescribed path, cutting the work piece with discharge sparks. wire should have sufficient tensile strength and fracture toughness. wire is made of brass, copper or tungsten. (about 0.25mm in diameter). Laser beam machining (LBM) In LBM laser is focused and the work piece which melts and evaporates portions of the work piece. Low reflectivity and thermal conductivity of the work piece surface, and low specific heat and latent heat of melting and evaporation – increases process efficiency. application - holes with depth-to-diameter ratios of 50 to 1 can be drilled. e.g. bleeder holes for fuel-pump covers, lubrication holes in transmission hubs. |
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