(4) Electrolytes for electrolytic grinding

Electrolytes for electrolytic grinding are mostly of conductive water solution containing inorganic acids, and since prevention of passivated layer formation is not required, emphasis is on the following two points.

(1) Has corrosion prevention properties.
(2) Has high electrical conductivity.

Corrosion inhibitors used are: NaNO2, NaNO3, KNO2, NaCO3, Na3PO4, borax (Na2B4O7), and other salts that cause high PH properties. High electrical conductivity is obtained by adding KNO3, NaNO3, KNO2, NaNO2, etc. Amines or other organic corrosion inhibitors are sometimes added.

For cemented carbides, WO3 and TiO2 are eluted from WC and TiC initially, so chemicals that dissolve them must be added.
The chemicals used for this are potassium sodium tartrate (Rochelle salt), phosphate, carbonate, and etc. Chemicals frequently used for hard-to-grind materials are shown in [Table 1].

[Table 1] Electrolytes used for various metals

For metals with high resistance to chemical erosions, electrolytes that include chlorides must be used. Although this type of electrolytes are highly corrosive to the processing system components, they are frequently used for rough machining where high removal speeds are required. Mixture of NaCL and boric acid is used for this purpose.

Electrolytes used for cemented carbides may also be used for other tool steel materials to avoid replacing the electrolyte when changing over from one work to another. If both material types are frequently mix ground on a system, both electrolyte types may be used as a mixture.