Nowadays, mold manufacturing technology is developing rapidly, while its processing quality is increasingly demanding. The quality and service life of mold materials directly affect the quality and economic benefits of processed products. Because of the high hardness and modulus of elasticity, good wear resistance and chemical stability, and the small expansion coefficient, the life span of the tungsten carbide die is several to several times higher than that of the die steel.

 

 

At present, fast wire electrical discharge machining (WEDM) has become one of the important means of die processing. In the process of on-line cutting, the working fluid plays the role of discharge medium, as well as cleaning and cooling. Actually, in the processing and production, the working fluid has great influence on the processing parameters. The chemical composition and physical mechanical properties of the tungsten carbide will be affected by the effect of high temperature as high as 10000℃ and the cooling effect of liquid medium at the moment of discharge.

 

Experimental study shows that, in the wire-electrode cutting of tungsten carbide die, tungsten carbide will be formed due to the oxidation of tungsten carbide on the surface of the cemented carbide die due to the effect of high temperature. After adding sodium carbonate, the solution is alkaline environment, and the tungsten acid root ion is easily formed, thus the degree of oxidation and dissolution of three tungsten oxide is aggravated.

 

After the shedding of tungsten trioxide, the continuous oxidation and dissolution of the inner layer of tungsten carbide promoted the leaching of W, thus reducing the hardness, wear resistance and service life of the tungsten carbide die. Adding borax, oleic acid triethanolamine and benzo three nitrogen in the working fluid can effectively inhibit the oxidation and dissolution of tungsten carbide and reduce the leaching of W. Some components in the processing fluid, such as sodium carbonate, can cause tungsten carbide (WC) to leach from the tungsten carbide surface and change its composition. 

 

On the other hand, it increases the difficulty of treatment of waste liquid from working fluids, resulting in increased cost, resulting in waste of resources and a certain degree of harm to the environment. The study of the effect of EDM on the leaching of tungsten carbide in cemented carbide dies is very useful for improving the performance and life of the die.