81 5 EDM Process Understanding the Wire（81 5 EDM过程的理解）.pdf

81 Understanding the Wire 5 EDM Process Accuracy and Tolerances Wire EDM is extremely accurate. Many machines move in increments of 40 millionths of an inch (.00004) (.001 mm), some in 10 millionths of an inch (.00001) (.00025 mm), and others even in 4 millionths of an inch (.000004”) (.0001 mm). Machines can achieve accuracies of +/-.0001” (.0025 mm); however, skim cuts need to be made to obtain such tolerances. See Figure 5:1. Courtesy Agie Figure 5:1 Precision Wire EDMing Finishes Extremely fine finishes of 12 rms can be produced with wire EDM. Wire EDM produces an excellent finish, even in the so-called “rough cut. Customers are often amazed when shown the fine finish of a single-pass cut. This fine finish is present, even after very large parts are cut, as in Figure 5:2. In other cutting operations, such as lasers and abrasive water jet, the larger the part, the rougher the finish. Wire EDM produces a smooth finish because the wire electrode goes through the entire part, and spark erosion occurs along the entire wire electrode. 82 Complet