How can you assess the quality of a wire EDM machine?
Release date:
2022-04-28
The development of wire EDM machines in China has also undergone more than a decade of twists and turns, evolving from the foundation of high-speed wire EDM technology. Initially, the control cabinets were equipped only with tool‑maintenance functions. As user demands grew, manufacturers increasingly recognized that, to enhance the overall performance of wire EDM machines, substantial improvements to the mechanical components were essential.
The development of wire EDM machines in China has also undergone more than a decade of twists and turns, evolving from the foundation of high-speed wire EDM technology. Initially, the control cabinets were equipped only with tool‑maintenance functions. As user demands grew, manufacturers increasingly recognized that, to enhance the overall performance of wire EDM machines, substantial improvements to the mechanical components were essential.
Ordinary users cannot be highly specialized; first of all, they can tell at a glance. The wire‑cut EDM control cabinet differs from a standard high‑speed wire‑cut EDM cabinet: it should be taller and larger. The machine’s external structure is at least a C‑pillar design, with the upper frame seamlessly integrated with the columns. The bed adopts a T‑shaped configuration, supported below by a full Y‑axis support system. The water shield features a fully enclosed water tray, and both the upper and lower columns are equipped with automatic wire‑tensioning devices.
The high-frequency power supply for the control cabinet must be connected to a 380 V mains supply. If possible, it should be powered by a dedicated voltage‑stabilizing power supply. The high-frequency board and drive‑board assemblies must be genuine components. In addition to the high-frequency board, an independent sample unit should also be provided. Each board should have its own separate power supply. At the very least, we can make a preliminary assessment of the machine tool’s quality by examining whether the wiring in the control cabinet is neat and well‑organized. Other components, such as resistors, inverters, and contactors, should also be genuine parts. In short, good components ensure a good machine tool. The next step is to evaluate the quality of the cut workpieces—precision, speed, and finish. We should also inspect the shape of the upper and lower drum sections, as well as the consistency when cutting multiple workpieces, along with molybdenum wire wear and the stability of continuous cutting. All these factors are critical indicators for assessing the quality of wire EDM machines during testing.
The five main reasons for wire breakage in medium-speed wire EDM:
1. The performance of the pulse‑power limiting diode degrades, and large negative voltage spikes during machining lead to increased wire‑erosion wear in a short period. Poor‑quality molybdenum wire or improper storage can cause oxidation, while using small iron rods or other unsuitable tools to stretch the wire during winding may result in wire damage.
2. The workpiece surface is not covered with a conductive film, such as when paint is damaged. Connect the workpiece to the positive terminal of the pulse power supply and the key wire to the negative terminal. If the workpiece’s coating makes poor contact with the positive terminal of the pulse power supply, electrical discharge machining cannot proceed, and the molybdenum wire may break. Therefore, it is essential to ensure a reliable connection between the workpiece and the positive terminal of the pulse power supply, and, if necessary, remove any coating from the workpiece surface.
3. After cutting the workpiece, the heavy scrap can become caught on the wire guide as it falls, causing the wire to break. When nearing completion of the cut, use a magnet to simultaneously pick up both the scrap and the workpiece, or secure them with a fixture (such as a pressure plate), and remove the scrap after machining is finished.
4. During the casting process, castings may develop sand holes and porosity, and non-conductive inclusions can be present within the workpiece, potentially causing wire breakage during cutting. For such parts, if conditions permit, inspection tools can be used to verify the uniformity of the internal material. If these conditions are not met, the machine tool’s instruments should be monitored continuously during machining, and any sudden changes in voltage or current应及时 addressed.
5. After heat treatment, non-conductive oxides and other impurities may remain at the cut edges or threaded holes of the workpiece, preventing proper cutting and causing wire breakage.
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