EDM processing machines provide precise precision, however, this process can be challenging. It is essential that the system of the machine is equally effective, especially its liquid management and the efficiency of the filter. This is the role of the magnetic filter, because it is able to filter fine particles and micron particles from the dielectric liquid of the EDM machine, ensuring the cleanliness of the liquid and protection from contamination.
Wire discharge machining (EDM), one of the most powerful and accurate cutting methods in manufacturing, has recently made a splash with its impressive capabilities, recently benefiting from dramatic improvements in machine capabilities as well as certain factors including machine structure, CNC control, contaminant removal rates, and cutting speed.
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EDM processing is expected to become a $6 billion industry by 2027, and the process is fast becoming a highly sought after specialty due to its ability to produce complex parts from conductive materials that would otherwise be impossible to process. But even with precise accuracy and high-quality results, the process can - and often does - have its own problems.
As machine capabilities advance, it is important to ensure that machine systems are equally efficient, especially fluid management and filter efficiency. Until recently, such a solution has been difficult to achieve. However, with the help of magnetic technology, many problems can be overcome, resulting in a significant increase in machine efficiency.
Electric discharge machining
Electrical discharge wire cutting (also known as spark machining or spark corrosion) is a metal fabrication process in which electrical discharge energy is used to etch workpiece material to obtain shape. There are three types of EDM, EDM wire cutting, conventional die and EDM drilling.
Cutting is produced by creating a series of high-frequency sparks between a conductive workpiece and an electrode, such as copper, brass, graphite or tungsten. When a spark jumps from the electrode to the workpiece, it picks up tiny particles that have been washed away by a dielectric fluid, usually deionized water or a specialized non-conductive oil.
Highly filtered dielectric fluids help produce high-precision and high-quality machined parts, and are essential for transferring charge during the process, flushing particles out of the gaps between workpieces to prevent them from forming Bridges that cause short circuits.
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Obstacles in EDM processing
Contaminated or dirty dielectric fluid can negatively affect the discharge machining process, resulting in problems such as slower cutting speeds, lower metal removal rates, reduced quality, and scrap parts with poor quality control. Without proper filtration methods, particles can deposit and accumulate within the necessary parts of the machine over time and begin to interfere with its capabilities.
The latest line corrosion or EDM machines require a high standard of surface finishing accuracy, typically a tolerance of 1-3 microns, and improved filtration can make a big difference in consistently meeting that standard.
While poor quality parts are a significant concern, particles that accumulate in dielectric fluids generally have more harmful and costly effects because they affect future workpieces as well as cause long-term maintenance issues. The solenoid valves that power the machine's pumps and circulate the fluid are easily damaged by this buildup, and these components are particularly fragile and expensive to replace.
However, secondary sparks or re-sparks are one of the main obstacles that occur during EDM processing, resulting in a high proportion of wasted energy generated. This occurs when metal particles are pushed out of the workplace and continue to flow in dielectric fluids. The fluid in the EDM process is constantly circulating, and without fast and effective filtration, the particles in the metal plate will remain in the system. Such particles can be as small as a micron; However, they can create a spark bridge between the electrode and the workpiece, ultimately slowing down the cutting process significantly.
For EDM wire cutters, these problematic particles in the dielectric fluid can also lead to an increase in wire breakage. Once the wire breaks, the machine needs to re-thread the wire through a dielectric jet. There should be no particles in the fluid to prevent further snagging the re-threaded wire, which in turn can cause further wire breakage, making the process unstable.
However, keeping wire breaking and re-threading to a minimum is key to the process, as automatic re-threading systems are time-consuming and unreliable, forcing the operation to stop completely in some cases. This is especially troublesome for 24/7 processes, as a lot of processing time can be lost due to a single break during a few hours of reduced staff resources on the shop floor.
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Magnetic filtration
The main purpose of the filter in EDM processing is to remove mechanical impurities from the dielectric fluid, maintain the efficiency of the machine and the quality of the parts, and protect the machine from premature wear and blockage. Magnetic technology provides effective fine particle filtration, removing even micron particles from dielectric fluids, ensuring a cleaner and more efficient fluid.
By combining magnetic filters with conventional spun or wool polyester or pleated paper barrier filters, fluids benefit from the highest level of protection. Using a barrier or medium filter alone can allow particles smaller than the pores of the filter to flow through, making the fluid vulnerable to secondary sparks. By introducing magnetic technology, combined with barrier filters, these particles can be quickly and safely removed, ensuring the removal of almost all contaminants.
Maintaining the correct flow rate and capacity during filtration is also important to ensure that the fluid system is working efficiently to provide clean fluids. If the filter cannot keep up with the speed of processing, it may result in a loss of fluid supply to the working area of the machine.
The Micromag magnetic EDM filter, designed and manufactured by Eclipse Magnetics, is one such innovation that provides a solution to many of the problems that arise during the EDM process and increases the yield of the machine. Its high-strength collection capability coupled with its high-strength magnetic core and optimized fluid flow direction can effectively remove almost all ferrous particles from dielectric fluids without affecting the flow rate of the fluid. Cleaner fluids help to significantly improve secondary sparks, significantly reduce broken lines, increase machine productivity and extend tool life.
This low-cost filter offers a quick return on investment - usually within a few weeks of installation - and, thanks to its easy-to-clean design, collected chips can be processed and recycled quickly and efficiently, greatly reducing the need for high-cost consumables.
