In the hardware processing and manufacturing industry, we should not be unfamiliar with slow wire walking processing and fast wire walking processing. They all refer to WEDM machine tools, so these two processing technologies
What’s the difference? Let’s take a look at the following:
- Development status of slow wire processing technology
Multiple cutting technology is the fundamental means to improve the machining accuracy and surface quality of slow wire walking. Generally, it is formed by one-time cutting, the accuracy is improved by two-time cutting, and the surface quality is improved by more than three times cutting.
Due to the lag of electrode wire when cutting corners, the corners will collapse. In order to improve the accuracy of corner cutting, more dynamic corner processing strategies are adopted. Such as: automatically changing the processing speed, automatically adjusting the water pressure, controlling the processing energy, etc.
The high-precision finishing circuit adopted by the advanced slow wire machining machine tool is an effective technology to improve the flatness of the machined workpiece, which significantly improves the machining accuracy of thick parts; In order to carry out the micro finishing of small fillets, narrow slots, narrow grooves and micro parts, the CNC low-speed WEDM machine tool can use 0.02 ~ 0.03 mm electrode wire for cutting.
In order to ensure high-precision machining, the mechanical accuracy, pulse power accuracy and servo control accuracy of the machine tool (including the control of mechanical motion, pulse parameters, wire feeding system and working fluid system) have reached a high level. The water temperature cooling device is adopted to make the internal temperature of the machine tool the same as the water temperature and reduce the thermal deformation of the machine tool; The closed-loop digital AC (DC) servo control system is adopted to ensure excellent dynamic performance and high positioning accuracy. The machining accuracy can be controlled within several microns, and the precision positioning can be realized by 0.1 μ M equivalent control; Immersion machining is adopted to reduce the thermal deformation of the workpiece; Motor servo, closed loop electrode wire tension control; The voltage modulation tool setting power supply is adopted to realize high-precision tool setting, and the tool setting accuracy can reach 0.002 mm without damaging the workpiece, whether dry or wet.
- Advantages of medium wire walking processing technology
Medium speed wire cut electrical discharge machining (ms-wedm for short) belongs to the category of reciprocating high-speed WEDM machine tools. It realizes multiple cutting functions on the high-speed reciprocating WEDM machine, which is commonly known as “medium speed WEDM”. The so-called medium wire walking processing does not mean that the wire walking speed is between high speed and low speed, but a composite wire walking WEDM machine tool, that is, the wire walking principle is to use high-speed (8-12m / s) wire walking during rough machining and low-speed (1-3m / s) wire walking during finish machining. In this way, the work is relatively stable and the jitter is small, and the errors caused by material deformation and molybdenum wire loss are reduced through multiple cutting, The processing quality can be between high-speed wire walking machine and low-speed wire walking machine. Therefore, what users call “medium wire walking” is actually a reciprocating wire EDM machine, which draws lessons from the processing technology of some low-speed wire walking machines, and realizes stripless cutting and multiple cutting.
Like the second cutting, the wire feeding mode adopts low-speed wire feeding and speed limiting feeding. In the machining process of medium wire walking technology, attention should also be paid to deformation treatment for multiple cutting, because during on-line cutting of workpiece, with the action of original internal stress and the influence of machining thermal stress caused by spark discharge, there will be non directional and irregular deformation, resulting in uneven thickness of cutting draft, affecting machining quality and machining accuracy. Therefore, it is necessary to reserve different machining allowance according to different materials to fully release the internal stress and complete torsional deformation of the workpiece, and there can be sufficient allowance for finish cutting in subsequent multiple cutting, so as to ensure the subsequent size of the workpiece.
- Advantages of fast wire walking processing technology
As the name suggests, fast wire walking processing is named because the electrode wire runs at high speed in the cutting process. Fast wire processing machine tool is an electrical processing machine tool created by Du in China. After decades of continuous improvement and development, it has become an important processing means in the manufacturing industry. It can meet the requirements of medium and low-grade mold processing and other complex parts manufacturing, and occupies a considerable weight in the medium and low-grade market.
At present, the technical index of fast wire processing machine tool: the efficiency of one-time cutting is 180 mm ²/ Min, the surface roughness after multiple cutting is RA ≤ 1.0 μ m. At this time, the average efficiency is 50 mm ²/ Min, the machined surface is glossy without obvious cutting stripes, the machining accuracy is 0.01 mm, and the electrode wire loss is ≤ 0.01 mm / 200000 mm ² 。 These performance indicators look good, but it should be noted that all links need to be ensured to obtain these indicators. Once there are differences, such as changes in the concentration of working fluid and the loss of electrode wire, it will affect the stability of processing quality.
Due to the stronger social demand for product diversification and the obvious increase in the proportion of multi variety and small and medium-sized batch production, the traditional ordinary processing equipment used in medium wire walking processing has been difficult to meet the processing requirements of high efficiency, high quality and diversification. However, medium wire walking processing has the characteristics of simple structure, low cost and low use consumption, so it also has its living space. Compared with fast wire walking machine tool, slow wire walking machine tool has obvious advantages in machining efficiency, precision and surface quality. Although the price of slow wire processing machine tool is expensive, with the rapid development of manufacturing industry, it will be more and more used in various processing fields.
ken. tang@chengcg.com
About the author