Raw materials of the grinding instruments

Abrasive material

The ellectrolyticaly produced corundum is an abrasive material, consisting of the corundum (Al2O 3) and a few admixture. The industry produces a few sorts of the electrolyticaly produced corundum, also normal, white, chromous, titanium, zirconium, mono-corundum, spheroidal corundum.

White electrolyticaly produced corundum - consists of corundum (98-99%) and a few admixture(1-2%) as high- aluminous sodium aluminate and others minerals. They receive white electrolyticaly produced corundum by melting of the aluminium oxide in the arc furnace, as a result y-Al2O3 turns into a- Al 2O3. Melting is produced unbroken with the periodically output to the special iron moulding.

The white electrolyticaly produced corundum of it s chemical and physical structure is more homogeneous as normal. Granules of the white corundum own a high durability and sharp borders, they take root simply into the hard solid metals (nitrated, fireproof), make less heating- up as granules of the otheer sorts of the electrolyticaly produced corundum. Abrasive items made of white corundum differ on their stability, own good self- sharpening and secure high clearness of the processing surface.

They make grinding granules, grinding- and micro- powers of the white electrolyticaly produced corundum.

Titanium electrolyticaly produced corundum is an abrasive material, which is reserved during the melting in the arc furnace. Titanium oxide- nearly 0, 3-1, 0%. Electro-corundum with 2-3% titanium oxide is analogue of the normal electro- corundum of a high quality on it s properties; in this product absents ferroalloys and another harmful admixtures.

Titanium electro-corundum is made as grinding granules and grinding powers for manufacturing of the abrasive instruments, which are used for processing of the carbonic, construction and other formed and unformed steels.

Chromous electrolytically produced corundum is an abrasive material, which is received during the melting in the arc furnace with addition of the chrome oxide to2%. Thanks to this addition increase it s mechanical solidity and abrasive property of the granules in comparison with the granules of the white electro- corundum. During the expansion of the chrome oxide, intensifity of coloration grow up, mechanical solidity of the granules go down, abrasive property grow up.

Grinding granules and grinding powers of the chromuos electro- corundum are used for producing of the abrasive instruments on various bonds and of the grinding emery cloths.

The bond is sort of the abrasive instruments is very important for their solidity and working regime. They produce two sorts of the bonds for the grinding instruments: inorganic ( of the mineral origin ) and organic.

The vulcanize, epoxy and poly-vinyl-butyral bonds are organic.

The inorganic ( ceramic ) bonds represent often the multi-particle mixes, consisting in the definite proportion of the dump materials reduced to fragments: fireproof clay, fluxes ( feldspar, boron glass ), talcum and many other materials. With the purpose of raising the plastic properties they add to the abrasive- ceramic mass the sticky substances: dissoluble glass, dextrin, etc.

Ceramic bonds own a high fireproof, hydro-proof and chemical stability and concerning high solidity. According to conduct during the thermal processing they are divided into fusible ( glassy ) and caking ( porcelain ). The fusible bonds turn into the glass after cooling, the coking bonds are melted just partly and are like porcelain.

During the producing of the abrasive instruments there is an interaction between the fusible bonds and the abrasive granules, it secures a high solidity of the abrasive instruments.

The abrasive instruments of the ceramic bonding are more popular, than the instruments of the organic bonding, though the technology of their producing is more complete and longer. The shortcoming of the ceramic bond is it s high frail, as following the wheels of such bonding can t be used under the stock loads. The concerning low limit of solidity restricts use of such wheels in the cutting works, because they are thin ( < 3 sm. ) and can be destroyed under the side- load.