Workers who are engaged in wire cutting processing must possess the basic qualities of being conscientious and careful, avoiding mistakes, continuously summarizing their experiences in practice, constantly improving their wire cutting technology level, and improving the accuracy of the wire cutting processing. Moreover, they need to specialize in researching and developing higher precision wire cutting filters, producing wire cutting filters that are suitable for more machine tools, and contributing to the development of the wire cutting filter processing industry.
In wire cutting, many techniques are important, among which filtering technology affects the precision of parts. According to research, to achieve such fast electrical discharge machining (EDM) wire cutting speeds, the most critical technology is to develop and design a set of work fluid supply and filtering systems that can adapt to the needs of fast wire cutting, ensure a timely process, and eliminate the large amount of debris generated during wire cutting. The amount of debris filtered out by the filtration system is not very important, but the key to solving the problem is to quickly, effectively, and thoroughly filter out the debris generated during electrical discharge machining and wire cutting from the working fluid. According to extensive research conducted by the company, if debris is not filtered out in a timely manner, the working fluid will quickly lose its ability to perform fast wire cutting, resulting in roughness on the surface of the machined parts and affecting the dimensional accuracy of the machined parts.
Due to this situation, Charmilles has designed a new filtration system with as many as 2-4 filter elements, twice as many as the original. Two to four filter elements are installed in two filtering circuits, which can be used in a single circuit or filter debris twice at the same time. When cutting difficult parts, such as ultra-high parts, four paper filters can be installed for two-stage filtration. In general, only one filtering circuit with two paper filters is needed for filtering without affecting wire cutting. The filtering system with two filter elements is directly installed in the working fluid storage tank so that the filtration system can always operate under a certain working pressure, forcing debris to be filtered out through the filtration system. In addition, the use of high-density multi-layer paper filters is said to increase the filtration area by 54%, thus greatly improving the filtration accuracy. According to Charmilles, doubling the number of filters can double the service life of the filtration system, increase the service life of the filtration system components by 2.6 times, and increase the unmanned EDM cutting time by more than 3.8 times, reducing processing costs by 40%. After high-precision filtration of debris in the working fluid, only clean working fluid flows between the electrode wire and the part, expanding the flow area of the working fluid so that parts can perform electrical discharge machining with wire cutting under ideal control of wire cutting parameters adjusted as required by the pulse generator, without any obstacles or interference, greatly improving the machining accuracy of parts. The Robofil company has equipped its 240CC and 440CC wire cutting machines with a new CC pulse power supply produced by Charmilles, which is a pulse generator characterized by a greatly increased ignition voltage and higher maximum amplitude capability. This enables the cutting parameters, such as ignition voltage, current size, pulse frequency, and amplitude size, to be adjusted according to the machined parts, generating the most ideal “shape” of the pulse spark for fast EDM wire cutting.
In addition, clean working fluid can greatly improve its cooling efficiency and reduce internal stress that can cause wire breakage, which is especially important for cutting thick and tapered parts. The use of the new wire cutting filter system also has several advantages that solve the following two problems satisfactorily:
The discharge gap between the workpiece and the electrode is an area where debris is not desired to have a negative effect, as when metal debris contacts the wire, it will produce unwanted electrical sparks that corrode the wire, reducing its lifespan.
If the debris in the working fluid is not filtered out, it will remain in the working fluid for a long time, causing scratches and wear on the sealing components of the working fluid storage tank and eventually damaging its sealing effect, affecting the processing effect, and increasing the auxiliary replacement time. The new filter system can also enable the wire cutting machine to perform high-precision cutting of large and heavy parts on a large workbench. Therefore, this new wire cutting filter is becoming more popular among users, as it offers many superior performance advantages over traditional wire cutting filters, enabling higher precision wire cutting. The filtration technology used in high-speed wire cutting filters is described above.