Jan 06, 2020
EDM wire cutting is a new process developed on the basis of EDM. It uses moving fine metal as a tool electrode, passes a pulse current between the wire and the workpiece, and uses the electrical corrosion effect of pulse discharge Cutting the workpiece.
CNC wire-cut machining parts have high precision and are suitable for the processing of complex planar shapes. They have the characteristics of flexible application, short processing cycle and material saving.
At present, in the research and development of new products, a large number of CNC cutting technologies are used to directly cut parts, which shortens the development cycle. However, if the advanced machine does not attach importance to the technology of processing, operation skills, and reasonable technology, it will not be able to efficiently process high-quality workpieces. Therefore, in actual operation, we must pay attention to the relevant processing technology.
1. Features of CNC EDM
With the popularization of CNC EDM machines, EDM machines have gradually shifted from a single blanking die processing to the processing direction of various parts. Its applications are becoming more and more widespread.
CNC wire cutting has the same features as EDM. The hardness and toughness of metal materials do not affect its processing. Wire EDM is mainly used to process hardened and hard alloys; most of the current log EDM machines use digital Program control, its process characteristics are as follows:
It is used to process complex shaped workpieces that are difficult or impossible to be processed by general cutting methods, such as punching dies, concave and convex dies, and precision parts with complex shapes.
Instead of manufacturing tool electrodes of a specific shape like EDM, copper wires or molybdenum wires with different diameters are used as the tool electrodes. Therefore, the cutting tool is simple, which greatly reduces the production preparation time.
The diameter of the electrode wire is thin (0.025-0.3mm) and the slit is very narrow. This is not only conducive to the use of materials, but also suitable for processing small parts.
The electrode wire is moved during processing, and it can be continuously updated (slow wire) or repeatedly used (fast wire). The effect of electrode wire loss on processing accuracy can be completely or shortly ignored.
Relying on the computer to calculate and control the electrode wire trajectory and offset trajectory, the fitting gap of the concave-convex mold can be easily adjusted, and the tapered cutting function can be used to realize the one-time processing of the concave-convex mold.
2.Wire cutting process
Machining of thin workpieces
The so-called thin workpiece generally refers to work with a thickness of less than 5mm. For example, it is difficult to ensure the machining accuracy of such workpieces such as samples and mechanical parts.
The main reason is that the opening distance of the upper and lower wire guide wheels of the wire rack is fixed, about 70mm. When cutting thin workpieces, under the condition of fast-moving wire, the electrode wire loses the damping effect of the cooling liquid that should be generated when processing thick workpieces Coupled with the effects of spark discharge, the wire is prone to jitter.
In addition, the speed of cutting thin workpieces is fast, and the frequency conversion feed is also fast. The speed of stepper motors has a certain technical range. When the speed is too fast (referring to exceeding the highest pulse frequency it can withstand), it will cause lost and lost steps. Will affect the machining accuracy of the workpiece. In order to overcome the above phenomenon and ensure the machining quality of thin workpieces, the following measures are recommended:
① Adjust the processing voltage to 50V.
②Less than 10μs when adjusting pulse width.
③The processing current is controlled within the range of 0.2-0.3A.