Wire electrical discharge machining (WEDM) is an important technology, which demands high-speed cutting and high-precision machining to realize productivity and improved accuracy for manufacturing hard materials. WEDM has experienced explosive growth and complexity of equipment as well as rising demand for the basic process tool (the wire electrode). Greater taper angles, thicker workpieces, automatic wire threading, and long periods of unattended operation make the selection of the ideal wire a much more critical basis for achieving successful operation. This paper focuses on the evolution of EDM wire electrode technologies from using copper to the widely employed brass wire electrodes and from brass wire electrodes to the latest coated wire electrodes. Wire electrodes have been developed to help user demand and needs through maximum productivity and quantity by choosing the best wire. In the final part of the paper, the possible trends for future WEDM electrode research are discussed.

/pdf/review-of-improvements-in-wire-electrode-properties-for-ffpqu0qg3n.pdf

Review of improvements in wire electrode properties for longer working time and utilization in wire EDM machining

A wire electrode for spark erosion cutting of metals, electrically-conducting ceramics etc., comprising either a homogenous centre (1) made of a metal or of a metal alloy, or a composite centre made from a steel core with a coating of copper or copper alloy, wherein the wire electrode comprises at least two sheath coatings made of zinc alloys, with said coatings wearing during erosion. In order to increase performance during high-speed cutting, such a wire electrode comprises an inner sheath coating (2) predominantly comprising .beta.-brass, and an outer sheath coating (3) predominantly comprising -y-brass, wherein the fraction of .beta./.beta.'-phase or y-phase in the two sheath coatings is at least 60 %. The ratio of the coating thickness of .beta.-brass to y-brass is between 0.3 and 7. The sum of the thicknesses of both sheath coatings in relation to the external diameter of the electrode is between 0.1 and 0.3.

Wire electrode for spark erosion cutting

Disclosed are an electrode wire for electro-discharge machining and a method for manufacturing the same. The electrode wire includes a core wire including a first metal including copper, a first alloy layer formed at a boundary region between the core wire and a second metal plated on an outer surface of the core wire due to mutual diffusion between the core wire and the second metal, and a second alloy layer formed due to diffusion of the first metal to the second metal. A core wire material is erupted onto a surface of the electrode wire for electro-discharge machining, which includes the core wire, the first alloy layer, and the second alloy layer, along cracks appearing on the second alloy layer, so that a plurality of grains are formed on the surface of the electrode wire.

Electrode wire for electro-discharge machining and method for manufacturing the same

One of the major requirements of wire electrical discharge machining (WEDM) is to develop suitable technology for producing smooth surfaces. The main characteristic of WEDM is the development of the white layer. To ensure good surface quality, the white layer thickness (WLT) must be as thin as possible, homogeneous, and crack-free. Spark energy and wire electrode type are the most important parameters to experimentally investigate WLT. Experimental results show that the WLT increases linearly by 3 and 2 µm for every 20-µJ increase in the spark energy while using brass and coated wire, respectively.

1.9 Effect of Electrical Discharge Energy on White Layer Thickness of WEDM Process

The electrode wire according to the invention comprises a brass core (1) covered with a γ phase brass coating (2) having a structure fragmented into blocks (2 a) between which the core (1) is exposed. The blocks (2 a) have a thickness (E2) with a narrow distribution and produce a coverage of the core (1) according to a coverage rate greater than 50%. This produces a regular fragmentation of the coating, which improves the finish state of the machined parts.

Electrode wire for spark erosion

The invention concerns an electrode wire comprising an unalloyed copper core (16) coated with a diffused zinc alloy coating layer (17), whereof the thickness (E) is more than 10 % of the wire diameter. The coating layer (17) is optionally plated with a thin zinc, copper, nickel, silver or gold surface contact film (21). Such a wire achieves higher electrical discharge machining speed

Ly Michel

Papers

Wire for high-speed electrical discharge machining

Wire for high-speed electrical discharge machining and producing method and usage thereof