Abrasive materials

Tools made by “ANDRE” contain modern, hard abrasive materials.

Aluminum oxide (synthetic corundum) - αAl2O3
Aluminum oxide in different variations is the most frequently used abrasive material.
It is melted from bauxite or aluminium oxide at temp. over 2000ºC in electric furnaces.

95A - Normal aluminium oxide (brown)
It is prepared from bauxite. Contains 96% Al2O3~3% titanium dioxide (TiO2) and 1-2% other admixtures.
It is the most resistant synthetic corundum and is characterized by its high ductility. It is used for cutting-off and rough grinding of low-alloy steels, stainless steels, cast iron, especially for high rates of stock removal.

97A - Semifriable aluminium oxide (grey)
It is prepared from calcinated bauxite with aluminium oxide addition. Contains 98% Al2O3 corundum and is characterized by medium hardness and strength. It is used for precision grinding and tool grinding.

99A - Friable aluminium oxide (white)
It is prepared from pure aluminium oxide. It is the purest synthetic corundum and contains over 90 % Al2O3. It is characterized by its high hardness and brittleness. It is used for precision grinding, e.g. surface and cylindrical grinding, sharpening of cutting tools.

CrA - Chromium aluminium oxide (pink)
It is prepared from aluminium oxide with an addition of up to several percent of chromium oxide. It is characterized by its high hardness and higher strength in comparison with white aloxite. It is used for precision grinding of high-alloy steels, sharpening of cutting tools.

M - Monocorundum (grey)
It is prepared from bauxite by reduction process. Contains over 99% Al2O3. It is characteri¬zed by its high microhardness and mechanic strength and has an excellent self-sharpening ability. It is used for grinding of high-alloy high-speed steels and sharpening of tools. Excellent for grin¬ding of complex profiles.

ZrA - Zirconia aluminium oxide
It is prepared from aluminium oxide or bauxite with an addition of zirconium dioxide. It is characterized by the highest microhardness and mechanic strength among other aloxities. It is used for highly efficient grinding of cast iron, grinding of steel semiproducts using high pressures.

Silicon carbide (carborundum) - SiC.
Prepared from high-silica sand of high purity and petroleum coke in resistance furnaces using the synthesis process. The second, after diamond, in respect to hardness.

99C - Green silicon carbide
High purity silicon carbide is green and contains 99% SiC min. It is used for grinding of sintered carbides, ceramics, stones, sharpening of cutting tools with sintered carbide inserts.

98C - Black silicon carbide
Contains 98% SiC and more amount of admixtures. Similarly to 99C, it is used for grinding of sintered carbides, ceramic materials, concrete, stone, rough grinding of castings (fettling) made of hard and fragile white cast iron and for cutting of concrete, stone and white cast iron.

 

Table 1: Grain sizes in accordance with FEPA 42-D-1984 and PN/M-59107 Standards

 

Macrograins

Micrograins

FEPA
designation
Mean sizes
of grain [mm]
FEPA
designation
Mean sizes
of grain [mm]
FEPA
designation

Mean sizes
of grain [μm]

F4

5,600 - 4,750

F36

0,600 - 0,500

F230

56,0 - 50,0

F5

4,750 - 4,000

F40

0,500 - 0,425

F240

46,5 - 42,5

F6

4,000 - 3,350

F46

0,425 - 0,355

F280

38,5 - 35,0

F7

3,350 - 2,800

F54

0,355 - 0,300

F320

30,7 - 27,7

F8

2,800 - 2,360

F60

0,300 - 0,250

F360

24,3 - 21,3

F10

2,360 - 2,000

F70

0,250 - 0,212

F400

18,3 - 16,3

F12

2,000 - 1,700

F80

0,212 - 0,180

F500

13,8 - 11,8

F14

1,700 - 1,400

F90

0,180 - 0,150

F600

10,3 - 8,3

F16

1,400 - 1,180

F100

0,150 - 0,125

F800

7,5 - 5,5

F20

1,180 - 1,000

F120

0,125 - 0,106

F1000

5,3 - 3,7

F22

1,000 - 0,850

F150

0,106 - 0,075

F1200

3,5 - 2,5

F24

0,850 - 0,710

F180

0,090 - 0,063

-

-

F30

0,710 - 0,600

F220

0,075 - 0,053

-

-