What is the difference between WEDM-LS, WEDM-MS?
Mar. 11, 2021
In metal processing and manufacturing industry, everyone should be familiar with WEDM-LS, WEDM-MS and WEDM-HS. They all refer to WEDM machine, which are widely used in mould manufacturing industry. So what is difference between these three processing technologies?
Medium-speed Wire Cut Electrical Discharge Machining(MS-WEDM) belongs to category of reciprocating high-speed wire EDM wire cutting machine. It is a multi-cutting function on high-sped reciprocating wire EDM machine. It is commonly known as "medium wire cutting". So-called middle wire processing does not mean that wire speed is between high speed and low speed, but a composite wire cutting machine. That is, wire routing principle is to use high-speed(8-12m/s) wire for roughing and low-speed(1-3m/s) wire for finishing, so work is relatively stable, jitter is small, and error caused by material deformation and molybdenum wire loss is reduced by multiple cutting, so that processing quality is relatively improved, and processing quality can be between high speed wire machine and low speed wire machine. Therefore, user said that "WEDM-MS”is actually a reciprocating wire EDM machine that draws on processing technology of some low-speed wire-cutting machines and realizes stripless cutting and multiple cutting.
In practice of WEDM-MS, it is concluded that the first cutting task in multiple cutting is mainly high-speed stable cutting, high peak cuttent can be selected, and current pulse cutting can be performed with a longer pulse width to obtain a higher cutting speed. Task of second cutting is to refine and ensure dimensional accuracy of machining. Medium gauge can be selected so that roughness Ra after second cutting is between 1.4 and 1.7 μm. In order to achieve purpose of finishing, low-speed wire-teaveling method is usually adopted, wire-traveling speed is 1-3m/s, tracking feed rate is limited to a certain range to eliminate round-trip cutting stripe and obtain required processing dimensional accuracy. Third, fouth or more cutting task (currently middle wire control software can achieve up to secen cut) is polishing which can be polished with a minimum pulse width (currently the smallest can be divided to 1 μs). Peak current varies with quality of machining and does not change sizt of workpiece.
Wire-trveling method uses a low-speed wire-feeding speed limit feed like second cutting. In process of machining, cutting process needs to pay attention to deformation process. Because workpiece is cut in line, it will produce non-directionality due to influence of original internal stress and machining thermal stress generated by spark discharge. Irregular deformation makes thickness of cutting behind knife uneven, which affects processing quality and processing accuracy. Therefore, different machining allowance should be reserved according to different materials, so that workpiece can fully release internal stress and complete torsional deformation, and there can be sufficient margin for finishing cutting in multiple subsequent cuttings, so that final size of the workpiece can be guaranteed.