CBN grinding fluid

Water soluble grinding fluid for CBN (Cubic boron nitride)

CBN (Cubic Boron Nitride) grinding wheel maintenance involves regular cleaning to remove loaded metal, using dressing sticks (like aluminum oxide) to expose new grit, and storing wheels in dry, temperature-controlled environments to prevent corrosion. CBN wheels should be used at slow speeds and, unlike diamond, are ideal for high-speed steel (HSS)

CBN (Cubic Boron Nitride) grinding lubrication primarily requires oil-based coolants (neat oils) to maximize wheel life and surface finish, particularly for high-speed or hardened steel applications. Oil prevents CBN wheel clogging, reduces friction, and prevents hydrolysis, unlike water-based emulsions which can cause wheel breakdown at high temperatures

PRODUCT	COMPOSITION	pH-value	APPLICATION	PDF
Molylub SynGrind CBN	SHC-POE base oils	9.2	CBN grinding wheels with vitrified bonds (VIT-CBN)

Molylub SynGrind CBN grinding fluid

It is known that the G ratio of CBN grinding is lower when water based coolants are applied, leading to higher tool costs. The chemical decomposition of CBN is frequently associated with its interaction with high temperature steam in grinding. This interaction can be similar to the phenomena described in where CBN grains can be destroyed in the wheel firing process where several constituents of the bond are chemically reactive with the grains. These oxidation reactions result in the formation of Boron oxide (B2O3) on the surface of CBN grains, a protective layer that prevents further oxidation.

Water based grinding fluid

A water based grinding fluid would not be successful in cases where the described reactions are relevant to the process performance. So, the study of these phenomena should be the first step before trying to develop a water based fluid for grinding.

The resulting CBN grains from the chemical reactor test were evaluated qualitatively using X-Ray diffraction spectroscopy and the water samples from grinding tests were analyzed quantitatively by Inductively Coupled Plasma-Optical Emission Spectroscopy. While the objective of the first test was to verify the existence of the described reactions, in the second test the concentration of Boron in water was determined. CBN is chemically very inert but it can be hydrolyzed by steam resulting in B2O3 and NH3. However the temperature for this reaction is not well known. Since grinding temperatures can reach 600°C in normal conditions the test was performed using 600°C as maximum value.

The chemical reactions between CBN grains and water are not a significant factor in the wheel wear mechanism in the tested conditions.

• The proposed vegetable oil based soluble grinding fluid provided good results in the grinding tests similar to the ones obtained with the neat oil. Wheel wear, grinding forces and surface roughness were reduced when the new cutting fluid diluted at 45% was used.
• The fluid proposed in this work has fulfilled all environmental requirements and provided a good grinding performance. This opens new perspectives for the development of fluids for CBN grinding.

Using clean, high-performance coolants has additional benefits, such as extending the working life of the grinding wheel, ensuring the surface quality of manufactured parts remains consistent, and reducing the maintenance work required on the machine.