Refer this study http://www.aspe.net/publications/Annual_2004/POSTERS/5PROC/4NCONV/1660.PDF : The dielectric plays an important role as the working fluid. During machining, the melted material by heat is dispersed into dielectric. The presence of minute metal particles (gap debris) contaminates dielectric fluid. It affects the material removal rate and properties of the machined surface because it exists in the spark gap between work and electrode.

If you desire to have wear resistance on freshly cut surface, you may as well experiment with urea solution in De-ionized water as an electrolyte; TiN gets formed from nitrogen ions released from electrolyte.

The question of the influence of the dielectric and its "electric" conductivity is already of great importance. The specified items of Kim (2004), however, refers to publications in the 90s. There are more recent literature on this topic (see my publication list), where more address the effects. When you go WEDM mostly from de-ionized water, ie the electrical conductivity must be controlled. Going 1-2 µS / cm as base value in dielectric container, then can be adjusted with a steel gap conductivity of 15 to 50 µS / cm. For hard metals (WC-Co, TiC, TaC) even higher values (100 to 200 µS/ cm) can be achieved. Contamination leads firstly to increase the electrical conductivity (electrochemical effects), on the other hand changes in breakdown conditions are achieved by the removal particles.

I have a query in line with this topic.

Is flash point of the dielectric fluid a critical factor in EDM process? If yes, how will it affect the material removal and electrode wear?

Refer Dielectric Fluid Guide for "FLASH AND FIRE POINT"

• The flash point of oil is the lowest temperature at which the vapor will ignite if a small flame or spark is present.
• The oil will not ignite by itself, there must be a flame or spark present. In addition, oil at it’s flash point will not burn continuously as it will only ‘flash’ or burn for a moment.
• The fire point is the temperature at which the vapor concentration of a fluid is sufficient to sustain a fire.
• Generally, the higher the flash point the safer the fluid.
• EDM fluids should have a flash point above 180°F. Usually the higher the flash point, the higher the viscosity.
• Depending on your application, such as fine finishing, you may want a lower viscosity fluid which will sacrifice flash point.
• Fine finishing with low amps will require a low viscosity fluid because your gap will be narrow.
• Higher amp projects, such as roughing, will require a high flash point and the viscosity is not of a major concern.

http://www.edmzap.com/documents/EDM%20Zap%20Dielectric%20Fluid%20Guide%20email.pdf

First of all thank you for the reference, which is valid only for hydrocarbons. However, the question of Murugesh referring to the WEDM and there is still work to 95% with deionized water.

When WEDM must expect two factors. Due to the dielectrics for very high electrical conductivity occur electrochemical side effects that influence the surface structure. The oxygen content can increasingly take place oxidation of tungsten. Thus we have changed conditions in the working gap, which contributes in poor flushing to a reduction of productivity and deterioration of the surface.

To Reply Govind would still be added that the "real" burn even oxygen is necessary, which does not exist in the case of bath-rinses. The latest use of hydrocarbons in the WEDM therefore requires also a bath flushing.