Among the many precision machining technologies, slow wire machining plays an important role in the field of high-value part machining due to its excellent machining precision. To what extent has it evolved in recent years? Maybe you still have limited knowledge about this topic, let’s explore the most remarkable level of slow thread processing today!
1
The level of slow yarn processing technology
1) Processing accuracy
The state-of-the-art slow wire processing has reached an incredible level of precision. Specifically, some state-of-the-art slow wire processing equipment can already achieve nanometer-level processing precision.
This means that slow wire processing can control the processing quality of nanoscale parts, so that surface roughness, shape and dimensional errors can be minimized. This is essential in areas that require very high precision parts, such as microelectronic product manufacturing, optical equipment manufacturing, and medical device production.
In order to ensure ultra-high precision processing, mechanical precision, pulse power precision and servo control precision of the machine tool (including control of mechanical movement, pulse parameters, of wire moving system and working fluid system) have reached an extremely high level. . The machine tool thermal balance control system is used to balance the internal temperature of the machine tool and eliminate the thermal deformation of the machine tool as much as possible; The closed-loop control system is used to ensure dynamic performance and high-precision positioning accuracy.
Due to the hysteresis of the electrode wire when cutting corners, the corners will collapse. In order to improve the corner cutting accuracy, more dynamic corner processing strategies are adopted. Such as: automatic change of treatment speed, automatic adjustment of water pressure, treatment energy control, etc.
The current main indicators of slow wire processing accuracy: dimensional accuracy can be controlled within 1 μm; the true roundness is less than 0.8 μm; precise positioning can achieve nanolevel equivalent control, and the pitch accuracy within 100mm can reach ±0.5μm even if achieved. can also achieve ±1μm step accuracy when processing the full stroke range of 500mm large jig; the shape accuracy of the lead frame cutting contour can reach ±0.5μm, and a small internal angle of 0.02mm can be processed;
2) Surface quality
In the past, surface roughness at the micron level was considered a fairly high-level machining result. However, with the continuous development of technology, the most advanced slow wire processing technology has achieved sub-nanometer surface quality, and the surface roughness index can reach Ra0.05μm, providing strong support for high precision applications.
Advanced slow wire processing machine tools use non-electrolysis pulse power supply with average voltage of zero, and the damage of electrolysis has been reduced to a minimum. In addition, due to the improvement of pulse supply, a high peak value and narrow pulse width (microsecond level) are generally used. Most materials are released in the gas phase, which absorbs a lot of heat. the part cannot rise and the phenomenon of cracking is considerably reduced; not only is the processing efficiency high, but the surface quality is also greatly improved. Using electrolytic power source for wire EDM processing can control the surface deterioration layer below 0.5μm. The wear resistance of the carbide die cutting edge is no different from that of grinding, and is even better than mechanical grinding. More and more parts are processed by “cutting instead of grinding”.
3) Effectiveness of treatment
Due to the development of nanosecond large size peak current pulse power supply technology and detection, control and anti-interference technology, the processing efficiency of machines- Slow wire processing tools are also constantly improving. machine tools can reach 500 mm²/min. The processing efficiency of larger thickness parts presents practical technological improvements. For example, when cutting a 300mm thick workpiece, the processing efficiency can reach 170mm²/min. For processing parts of varying thicknesses, the maximum processing efficiency in this state can be achieved by automatically detecting the thickness of the part and automatically adjusting the processing parameters to avoid wire breakage.
In addition, the rapid automatic threading technology introduced by advanced slow wire processing machine tools has an automatic threading time of <15 seconds, which improves the efficiency of processing operations; the introduced double wire automatic exchange technology can automatically use 0.20~0.02mm; Electrode wires for performing double wire threading. Use thick wire for the first cut, generally with a wire diameter of 0.25mm, to improve processing efficiency and enable coreless cutting; then use fine wire for cutting, usually using 0.10mm fine wire, to cut small round corners, and can be improved. precision can save 30-50% of overall cutting time.
4) Automation, intelligence and computerization
During the processing process, in order to reduce human intervention and ensure that the expected process indicators are achieved, the automation, intelligence and computerization of slow yarn processing have achieved corresponding development.
The complete process expert system of the slow wire processing machine tool provides a complete set of parameters according to the processing requirements. It not only includes commonly used electrode wire brands and corresponding workpiece materials, but also provides processing parameters for special materials such as PCD and PCBN. It can be based on whether the upper and lower nozzles are in contact with the workpiece and how far apart they are. are, and whether to finish in the slot or in the open surface Repair, which should be prioritized between precision, surface roughness and efficiency? Strategies are used to generate respective specifications; The discharge expert system handles random factors during cutting and uses adaptive control during the processing process in situations such as cutting, cutting, cross-section changes, center cutting, near edge cutting , high-speed cutting of large sections, etc. Automated strategies and control functions enable stable and efficient processing of continuous yarns.
The automatic hole-free detection function is also very convenient. During automatic skip processing, if the pre-hole is forgotten or the hole position is shifted, the machine tool will automatically move to the next pre-hole, preventing the machine from stopping during unattended operation . Processing when a short circuit occurs after threading, the position of the short circuit can be automatically searched and eliminated, which improves the reliability of continuous operation without a driver.
The CNC system of the machine tool is equipped with a standardized mechanical interface to form an intelligent manufacturing system. Thanks to the manipulator of the 3R system or the EROWA system, the automatic exchange of parts (pallets) can be easily achieved with the expert system. and automatic electrode wire exchange technology, it can automatically complete all treatment processes.
2
The technical level of different grades of slow wire processing machine tools
Slow wire processing machine tools can be divided into four categories: high-end, high-end, mid-range and entry-level. Typical foreign manufacturers that produce slow wire machine tools include Swiss GF Machining Solutions (formerly AgieCharmilles), Japan West, Japan Mitsubishi, Japan Makino, Japan Sodick, Japan Fanuc, etc. Typical domestic manufacturers include Qinghong, Laitong, Jingcheng, Meixi, Sanguang, Ande, etc.
1) Top-notch slow wire processing machine tools
This type of slow wire processing machine tool represents the current highest level and is mainly manufactured in Switzerland and Japan. The processing accuracy of this type of machine tool can be guaranteed to ±0.001mm, the maximum processing efficiency can reach 500mm²/min, and the surface roughness can reach Ra0.05μm. It has perfect surface processing quality, with almost none. deterioration layer on the surface and can use Φ0.02mm electrode wire is micro-finished, the main machine has heat balance system, and some machine tools use oil cutting processing . This type of machine tool has complete functions and a high degree of automation. It can directly complete the precision processing of molds. The service life of processed molds has reached the level of mechanical grinding.
2) High-end slow wire processing machine tools
This type of machine tool is mainly produced by Swiss and Japanese companies. It has an automatic wire threading function, a resistance-free anti-electrolysis power supply and a global thermal constant system. It can use Φ0.07mm electrode wire for cutting and processing. the precision is ±0.002mm, with the highest processing precision. The efficiency can reach more than 300mm²/min, the surface roughness can reach Ra<0.1μm, and it has the function of timely detecting workpiece cross-sectional changes and actual changes. temporal optimization of discharge power. This type of machine tool is also widely used for processing precision stamping dies.
3) Mid-range slow wire processing machine tools
This level of machine tools is usually produced by Swiss and Japanese companies in manufacturing plants in China. The technical level of some Taiwanese machines can also reach this level. Their configuration and performance meet the requirements of most domestic precision wire cutting processes. Generally, a resistance-free anti-electrolysis power supply is used, which has the functions of submerged processing and taper cutting. The maximum practical processing efficiency is 150~200mm²/min, the best surface roughness reaches Ra<0.25μm, and the cutting precision is about ±0.003mm. Generally, electrode wires of Φ0.1mm and above are used for cutting and are. equipped with anti-collision protection. The system can prevent damage caused by programming errors or misuse, and is equipped or optionally equipped with an automatic wire threading mechanism.
4) Entry-level slow wire processing machine tools
This type of machine tool is generally a Taiwanese machine tool or a machine tool independently developed and produced in China. Its configuration and performance meet the processing requirements of ordinary household molds and parts. Generally, the process of cutting one and cutting one and cutting one and two can stably achieve a surface roughness of about Ra0.5μm and a processing precision of about ±0.005mm . Most can only use electrode wires 0.15mm and above for cutting. and the treated surfaces are good. There is a certain gap between the organization and the corners and advanced machine tools.
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