A table to help you sort out the differences between fast wire cutting and slow wire cutting machines

As the most commonly used and basic electrical machining wire cutting equipment in the stamping mold processing industry, wire cutting machine tools are believed to be very familiar to stamping mold practitioners. However, everyone is not very clear about the difference between fast wire cutting and slow wire cutting in high-speed cutting. Here I will give you a detailed introduction on the difference between fast wire cutting machine tools and slow wire cutting machine tools.

1. The wire running speed is different.
Fast wire cutting machine tools and slow wire cutting machine tools are distinguished according to the speed at which the electrode wire travels during operation.
The wire-traveling speed of fast wire-traveling machine tools is generally 300-700m/min.
The wire-traveling speed of slow wire-traveling machine tools is generally 3-15m/min.

2. The electrode wire materials are different.
The electrode wire of fast-moving wire machine tools generally uses molybdenum wire, and the diameter of molybdenum wire is generally 0.1-0.2mm.
The electrode wire of slow wire machine tools generally uses copper wire or other metal-coated wires with a diameter of 0.03-0.035mm.
3. The working fluid is different.
The requirements for fast wire machine tools are not too strict, and emulsions are generally used as working fluids.
The working fluid of the slow-moving wire machine tool is deionized water or kerosene, and it also needs to be equipped with a filtration system to continuously filter impurities in the working fluid during production.
4. The processing accuracy is different.
Fast wire-traveling machine tools use electrode wires cyclically for processing. As the electrode wires wear out, the processing accuracy is affected. The general accuracy of products processed by fast wire machine tools is ±0.015~0.02mm;
The electrode wire of the slow wire machine tool is not recycled, which greatly improves the processing accuracy. The processing accuracy of the machine tool can reach ±0.002mm;
5. Processing costs are different.
Fast-travel wire cutting machine tools are relatively common and have low technical content. There are many manufacturers and the machine tools are cheap. Moreover, the molybdenum wire is recycled, the processing efficiency is high, and the processing cost is low.
Slow wire cutting machine tools have high technical content and the equipment is expensive. Processing costs are also high.
With the advancement of technology, developers have developed a knife trimming function based on the fast wire cutting machine tool, which is also called the medium wire cutting machine tool. However, the machining accuracy is still far inferior to that of slow wire machine tools.
The author below will share with you a comparison table between slow wire cutting and fast wire cutting machines, so that you can compare them more intuitively.

ITEMS to Compare	Machine type:  High-speed wire cutting machine	Machine type: low-speed wire cutting machine
Wire speed	8-10m/s	0.001-0.25m/s
Wire walking method	Reciprocating silk supply, repeated use	One-way wire running, one-time use
Electrode wire material	Molybdenum, tungsten-molybdenum alloy	Brass wire, copper-based plating material
Threading method	Manual	Manual or Automatic
Electrode wire vibration	Larger	Smaller
Silk transport system structure	Simple	Complex
Working fluid	emulsion	Deionized water, or kerosene
Working fluid resistivity	0.5-50KΩ·cm	10-100 KΩ·cm
Guide wire mechanism type	Guide wheel, short life	Guide, long life
Machine tool price	Cheap	Expensive
cutting speed	20-40mm2/min	20-240mm2/min
Precision	0.01-0.04mm	0.004-0.01mm
Surface roughness Ra	1.6-3.2μm	0.1-1.6μm
Repeatability	0.02mm	0.004mm
Electrode wire loss	uniform loss	No losses
Product photo

Development status of slow wire processing technology

The continuous improvement of manufacturing accuracy and surface quality requirements for precision and complex stamping molds with longer service life has made fast wire processing technology no longer suitable for the manufacturing requirements of precision molds. This status quo has promoted the rapid development of slow wire processing technology, and its various In terms of process indicators, it has reached a very high level and is irreplaceable by other processing technologies.

Multiple cutting technology is the fundamental means to improve the accuracy and surface quality of slow wire cutting. Generally, it is formed by one cutting, two cuts improve the accuracy, and three or more cuts improve the surface quality.

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: automatically changing processing speed, automatically adjusting water pressure, controlling processing energy, etc.

The high-precision finishing circuit adopted by advanced slow wire processing machine tools is an effective technology to improve the straightness of processed workpieces, which significantly improves the accuracy of thick parts processing; in order to process small fillets, narrow slits, narrow grooves and fine For micro-finishing of parts, cutting-edge CNC low-speed wire EDM machines can use 0.02 to 0.03mm electrode wires for cutting.

In order to ensure high-precision processing, the machine tool’s mechanical accuracy, pulse power accuracy, and servo control accuracy (including control of mechanical movement, pulse parameters, wire walking system, and working fluid system) have reached an extremely high level. A water temperature cooling device is used to make the internal temperature of the machine tool the same as the water temperature, reducing the thermal deformation of the machine tool; a closed-loop digital AC (DC) servo control system is used to ensure excellent dynamic performance and high positioning accuracy, and the processing accuracy can be controlled within a few microns. Within the range, precise positioning can achieve 0.1μm equivalent control; immersion processing is used to reduce thermal deformation of the workpiece; motor servo, closed-loop electrode wire tension control; voltage modulated tool setting power supply is used to achieve high-precision tool setting, and the tool setting accuracy can reach 0.002mm. , without damaging the workpiece;.

Advanced slow wire processing machine tools use an electrolysis-free pulse power supply with an average voltage of zero, and the damage of electrolysis has been reduced to a minimum. In addition, due to the improvement of pulse power supply, high peak value and narrow pulse width (microsecond level) are generally used. Most materials are thrown out in the gas phase, which takes away a lot of heat. The surface temperature of the workpiece cannot rise, and the phenomenon of cracking is greatly reduced. Reduction; not only the processing efficiency is high, but also the surface quality is greatly improved. Using an electrolytic power source for wire EDM processing can control the surface deterioration layer below 2 μm. The wear resistance of the cutting edge of the carbide die 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”.

Due to the development of nanosecond-level large peak current pulse power supply technology and detection, control, and anti-interference technology, the processing efficiency of slow wire processing machine tools is also constantly improving. The maximum processing efficiency of current advanced slow wire processing machine tools can reach 500mm2/ min. The processing efficiency of larger-thickness workpieces has practical technological improvements. For example, when cutting a 300mm-thick workpiece, the processing efficiency can reach 170mm2/min. For the processing of workpieces with varying thicknesses, the machine automatically detects the thickness of the workpiece and automatically adjusts the processing parameters to prevent wire breakage and achieve the highest processing efficiency in this state.

In addition, the fast automatic wire threading technology introduced by advanced slow wire processing machine tools has an automatic wire threading time of <15 s, which improves the efficiency of processing operations; the double wire automatic exchange technology introduced can automatically use 0.20 ~ 0.02 mm electrode wires for double wire threading. Wire switching processing. Use thick wire for the first cutting, generally with a wire diameter of 0.25 mm, to improve processing efficiency and allow for coreless cutting; then use thin wire for trimming, generally using 0.10 mm thin wire, to cut small round corners, and can Improved accuracy can save 30% to 50% of cutting time overall.

During the processing process, in order to reduce human intervention and ensure that the expected process indicators are achieved, the automation, intelligence and informatization of slow wire 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, how far apart they are, and whether finishing in cutting wind or open surface. Repair, accuracy, surface roughness and efficiency which priority processing strategy to generate their own specifications; the discharge expert system copes with random factors in cutting, cutting in, cutting out, cross-section changes, center cutting, close to edge cutting, large In situations such as high-speed cutting of cross-sections, adaptive control strategies and automated control functions are used during the processing to achieve stable and efficient processing without continuous filament.

The automatic holeless detection function is also very practical. During automatic skip processing, if the pre-hole is forgotten or the hole position is offset, the machine tool will automatically move to the next pre-hole, thus preventing the machine from stopping during unmanned 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 unmanned operation.

The CNC system of the machine tool is equipped with a standardized mechanical interface to form an intelligent manufacturing system. Through the manipulator of the 3R system or the EROWA system, the automatic exchange of workpieces (pallets) can be easily realized. With the expert system and automatic electrode wire exchange technology, it can Automatically complete all processing processes.

The technical level of various grades of slow wire cutting machines

According to product grade classification, slow wire processing machine tools can be divided into four grades: top, high-end, mid-range, and entry-level.

Top-notch slow wire cutting machines are mainly manufactured in Switzerland and Japan; these machine tools have automatic wire threading function, resistance-free anti-electrolysis power supply, overall thermal constant system, and can use Φ0.07 mm electrode wire for cutting, with an accuracy of ±0.003mm about. It has perfect processing surface quality, with almost no deterioration layer on the surface. It can use Φ0.02 mm electrode wire for micro-finishing. Most of the main machines have a thermal balance system, and some machine tools use cutting processing in oil. 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 the processed molds has reached the level of mechanical grinding.

Secondly, there are also very outstanding companies in Taiwan and mainland China that are catching up with advanced technologies and benchmarking against top international brands. I believe that in the near future, Made in China will make greater progress in the field of high-end electrical machining!

Keywords: high-speed wire cutting machine , slow wire cutting machine , mold manuf