What are the causes of wire breakage in medium‑speed wire EDM, and how can they be resolved?
Release date:
2022-05-05
During wire EDM machining, wire breakage is unavoidable. If both ends of the wire‑feeding roller are functioning properly, the process can be resumed. However, if the wire breaks in the middle, the molybdenum wire must be removed, which is not only time‑consuming but also results in waste of the wire.
During wire EDM machining, wire breakage is unavoidable. If both ends of the wire‑feeding roller are functioning properly, the process can be resumed. However, if the wire breaks in the middle, the molybdenum wire must be removed, which is not only time‑consuming but also results in waste of the wire material.
The causes of wire breakage in medium‑speed wire EDM and their corresponding solutions are as follows:
I. Mechanical Section
1. The guide wheel is aged, damaged, or of poor quality, causing severe wire vibration and wire breakage.
Solution: When the guide wheel reaches the end of its service life, the bearing or the entire guide‑wheel assembly must be replaced. Using a waterproof jewel‑bearing guide wheel significantly extends its service life. However, ensure that the waterproof groove is oriented downward.
2. The wire‑guide nozzle (commonly referred to as the “eye mask”) may age or become damaged due to improper operation, resulting in molybdenum wire breakage.
The solution is to select appropriate ruby and diamond taps. The broken end of the molybdenum wire must be cut off with scissors. Before pulling out and threading the molybdenum wire, double-check repeatedly. If possible, prepare a fine sandpaper around grit 800 to grind down the tip of the molybdenum wire. For hard‑drawn wires, this step can damage the tap, as burrs will remain on the cut surface of the wire.
3. After prolonged use, the conductive block’s groove has not been replaced, resulting in the molybdenum wire becoming jammed and breaking.
The solution is to inspect the conductive block for dents, rotate it at a specific angle, periodically reposition it to a designated location, or replace it with a new one.
4. Aging of the molybdenum wire tensioning device results in uneven tension.
Solution: Check the tension of the molybdenum wire; verify that the spring or weight in the tensioning device is functioning properly.
5. Wire breakage caused by excessive tension: If the wire tension is too high during wire feeding, it can also lead to wire breakage; if the tension is too low when tightening the wire, the molybdenum wire will lack sufficient tension. Conversely, if the tension is too great, the molybdenum wire may snap.
The solution is to tighten the threads with appropriate torque. This is a critique of China’s medium‑speed wire EDM industry, which places high demands on operators’ technical expertise.
6. Wire stacking leads to wire breakage. Many workers mistakenly attribute wire‑bending issues to the wire‑cutting machine. In reality, this is caused by uneven stress applied during wire installation. Typically, layering occurs when using new molybdenum wire.
The solution is to turn the wire‑feeding roller to the left, first loosen the wire, unwind it one full turn, and then tighten it. If that doesn’t work, remove the molybdenum wire and rethread it. Improve your operating skills and use wire of appropriate strength.
7. During wire EDM machining, workpiece deformation can cause the molybdenum wire to become jammed or break.
The solution is to prevent material deformation during cutting and to employ an appropriate heat‑treatment process. First, perform a preliminary treatment on the threaded holes; carry out pre‑cutting to relieve residual stresses; and select process bosses to be retained for tool maintenance, while optimizing the wire‑EDM cutting path.
II. Electrical Section
1. Poor process parameters—not only excessive current; overly tight tracking and unstable cutting can lead to wire breakage.
2. The solution involves adjusting the machining parameters according to the material and workpiece thickness, and selecting appropriate pulse width, pulse interval, tracking settings, speed limits, and wire feed rate.
3. When cutting tall workpieces, wire breakage is likely to occur.
The solution is to select a larger pulse width and pulse interval for thick workpieces. Subsequent operations should also be adjusted accordingly. For detailed information, please consult the manufacturer.
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