EDM wire selection
he selection of EDM wire used to be easy as there were only a few choices; copper or brass. Today, there are more electrode choices for wire EDM than there are for sinkers. We have economy and utility-grade wires, wires for speed, wires for carbide and PCD’s, wires for tapering, and fine-wire machining. In this short study, we will first examine the different properties of EDM wire, then we will briefly examine the different types of wires and their applications.Tensile strength is the maximum load-bearing capability given to a material based upon its ability to resist stretching and breaking. It is determined by the maximum load in pounds per square inch divided by the cross-sectional area of the wire. High-tensile EDM wire provides better edge straightness and so is a good choice for single-pass parts and in small- and fine-diameter wires to reduce wire breakage. Wirecutting tall parts is another application that requires good straightness and resistance to wire breaks. High-tensile wire is also good for skim cuts, aiding in part straightness and geometric accuracy.There is no true index or “rating” of fracture resistance, so fracture resistance of an EDM wire might better be described as wire toughness or resilience. It is the ability of the wire to resist the effects of the incredibly dynamic environment of the spark gap.This is the measure of a material’s ability to carry electrical current. In EDM, the higher the conductivity of the wire, the more power can be delivered to the workpiece. Since higher conductivity is more efficient, increased cutting speeds are the usual results.A low melting/vaporization temperature of the wire will prove the best for flushability. We want the wire surface to vaporize, to quickly turn into gasses, instead of contaminating the gap with resolidified “chips”. All chips have mass and therefore, will “take up room”. The spark gap is small enough already and we don’t need “chunks of stuff” floating around in it. When using longer on times (roughing), melting will occur. Even though melting produces chips, lowtemp electrode alloys (zinc-coated) will produce larger craters on the wire surface to carry more water and contaminants away from the gap, aiding flushing. Consequently, moly and tungsten wires, with high melt/vaporization temperatures cut slowly and flush poorly, but are satisfactory for skim cuts where speed is not an issue but part straightness and crisp geometry is.The term hardness is often mistaken for tensile strength. The hardness or temper of a wire refers to the wire’s ductility, or its ability to undergo elongation. In this category, EDM wires are called soft or hard. On closed-guide machines, a hard wire will thread better than a softer wire, but a soft wire will taper-cut better. A hard wire will also provide the best auto-threading reliability.If has any high quality EDM products to custom-made, pls contact Lemo : Dongguan Lemo Precision Metal Products Co.,LtdAddress: No.84 Zhongli Rd,Nancheng,Dongguan,Guangdong,523000,China.Contact: Amy ChenTel: 86-769-8803 9052Mobile: 86-13713262409Fax: 86-769-8803 8031E-mail: [email protected]
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