In the presence of sulfur and halogen vapors, the energy required to cut the steel is greatly reduced. This theory has been proven for the use of composite grinding fluids and single-point cutting tools for ceramic grinding wheels. The cutting steel is known, the low melting point metal is an excellent lubricant, when manufacturing the grinding liquid people also use knowledge in this regard. Since the resin grinding wheel is generally used for dry grinding, no coolant is used during grinding, and thus it is not affected by halogen or sulfur vapor and low melting point metal. In view of this, these materials are usually added directly to the manufacture of resin bond grinding wheels.
When the grinding wheel is dry-grinded, sulfur or halogen vapors are present at the grinding point, which breaks the chemical bond of the steel, thereby greatly improving the ability to grind steel.
In some binders, metals containing a low melting point, in addition to increased grinding pressure and speed, also melt the steel itself. It is also beneficial to combine a low melting point metal with a binder. A resin grinding wheel for dry-grinding steel always contains a halogen or sulfur supply in its optimum formulation.
Chemically active fillers are very important when grinding stainless steel and alloy steels; they are not critical for carbon steel, and chemically active fillers are not superior when grinding non- ferrous metals.
1. Natural cryolite and pyrite
The chemical expression of natural cryolite is Na 3 A1F 6 . Cryolite powder is first used as a reinforcing material to increase the strength of the abrasive. Further, it was found that since the melting point of the cryolite is low, the effect of grinding heat during the grinding process, the cryolite is melted, and the abrasive grains are easily detached to prevent the clogging of the grinding wheel. In addition, the melted cryolite can be lubricated during grinding; and it precipitates fluorine, which is beneficial to the grinding of the steel, so the cryolite powder is adapted to the dry grinding wheel without the coolant during grinding. Practice has proved that, for the manufacture of ordinary grinding wheels, the reinforcing effect of cryolite powder is not as good as that of semi-hydrated gypsum powder, and its addition amount is generally 1.5% to 5%.
Pyrite (FeS 2 ) can be used in the form of fine powder. However, in the hot-formed high-density coarse-grained abrasive wheel, the pyrite has a particle size of about F 60 , and such a particle size is in the abrasive size and Between the size of the resin micropowder, it is added in the binder in an amount of 50% by volume of the micropowder filler; in the very coarse abrasive, coarse-grained pyrite is used, which is capable of accommodating a large amount of filler, and also has The ability to reduce the porosity to zero.
The mixture of natural cryolite and pyrite is an excellent filler. It is used to prepare high-strength coarse grinding wheels. These grinding wheels do not require metal lubricants, which can cause the steel to melt or at least soften during the operation of the grinding wheel. The cutting process is easier to carry out.
2. Zinc sulfide and synthetic cryolite
Cryolite is the first active filler used, and it has been the most widely used filler among all fillers. However, due to its resources, people began to use other materials instead.
Chemical name synthetic cryolite, potassium boron fluorine, chemical formula is KBF 4. An off-white crystalline powder that is slightly soluble in water. In fact, it is more active than natural cryolite. However, the addition of potassium fluoroborate reduces the tensile strength of the resin binder. Therefore, its usage is very small. Synthetic cryolite is usually used in combination with an inactive filler such as feldspar, and feldspar is used to improve the tensile strength of the binder while using potassium fluoroborate to improve the grinding performance.
Active filler zinc sulfide (ZnS) in the cutting of steel in a resin bonded grinding wheel has been widely used. It can be used in the form of natural minerals, sphalerite, and chemically precipitated powders, where the precipitated powder is more active and more expensive.
Third, lead chloride and barium sulfide
Lead chloride (PbCl 2 ), white crystal, density 5.85g/cm 3 , melting point 501 ° C, boiling point 950 ° C, insoluble in cold water, ethanol and ether, slightly soluble in hot water.
Grinding wheels made of these two materials have excellent cutting performance, but due to their cumulative toxicity, producers are not only harmed in the production process of preparation, mixing, molding, etc., but also under the action of grinding heat, these materials will Volatilization also harms the health of the user.
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