CBN grinding wheels

The choice of the correct CBN grinding wheel must be determined according to the customer’s specific application. The decisive factor is the optimum interaction between wheel dimensions, grain size, bond and concentration.

Our employees with their many years of experience will be pleased to advise you by telephone or at your site regarding a high-quality and cost-effective design of a CBN grinding wheel for your process.

Applications

CBN grinding wheels are used in a variety of applications. Below is a list of materials for which the use of CBN grinding wheels can be recommended:

  • High alloy tool steels with at least 55 HRC
  • chilled casting
  • Iron-based powder coatings
  • High-alloyed and hardened special steels
  • High Speed Steels (HSS)
  • Case hardened steel
  • chrome steel
  • Nickel-based superalloys
  • stellite
  • Soft steel qualities in certain applications

Bonds

The grinding behaviour of CBN grinding wheels is decisively influenced by the bond. The task of the bond is to optimally hold the abrasive grain at the grinding temperatures and grinding forces that occur and at the same time to create enough chip space for the removed material to be removed without any problems. Due to the large number of grinding problems that occur, a wide range of bonds is required:

  • resin bonds
  • metal bonds
  • galvanic bonds
  • ceramic bonds

Spectrum of bonds

Resin bonds

More than half of all grinding tasks can be accomplished with synthetic resin bonded CBN grinding wheels. The synthetic resin bond offers countless bond variations and very high stock removal rates.

TieCutRemark
K10Rdry / wetStandard bond with medium hardness
K2010wetFine ground binding especially for polishing
K40XwetVery hard binding with a long service life
K20Ndry / wetWide pads with soft standard binding
KX30dry / wetVery hard bond with long service life
K5020oilCopper bonding cutter wet/oil
K7010oilHard copper bond wet/oil
K41XoilCopper bond Cutter CNC (11V9+12V9) DIA+CBN Oil
WTX1oilCopper bond Cutter CNC (11V9+12V9) DIA+CBN Oil
WTX3oilCopper bond Cutter CNC (11V9+12V9) DIA+CBN Oil
AK600dryDry ground bond with good stock removal rate

Metal bonds

More than half of all grinding tasks can be accomplished with synthetic resin bonded CBN grinding wheels. Synthetic resin bonded metal bonds are characterised by very high grain retention forces. For the continuous self-sharpening of truncated CBN tips, large infeed forces are required, which produce increased heat generation. Metal bonds should therefore always be used for wet grinding. Dry grinding is possible with small contact surfaces and low cutting depth. (Profile grinding on PETEWE, Studer, Hommel and Loewe). Numerous bond variants and very high stock removal rates are possible.

Galvanic bonds

With electroplated nickel bonding, usually only one grain layer CBN is held (2- or 3-layer is conditionally possible). A special field of application for the S-bond with CBN as abrasive is the grinding of profiles in turbine construction.

Ceramic bonds

These bindings are characterized by porosity and profilability.

Concentration

The concentration determines the abrasive grain content (CBN) in the abrasive coating. The performance of CBN abrasive tools is determined significantly by the concentration. It influences the service life of the grinding tool, the profile retention, the stock removal rate and the grinding quality. This results in the following concentration gradations:

The basis for the concentration specification is the value C100, which corresponds exactly to 25% by volume of pure CBN in the abrasive coating.

For CBN this is the result:

C100 = 25 vol.% = 4.4 carat/cm3 (grinding wheel coating 1 kt = 0.2 g)

DesignationConcentrationpercentage by volume
C251,10 ct/cm36,25
C381,67 ct/cm39,50
C502,20 ct/cm312,50
C753,30 ct/cm318,75
C1004,40 ct/cm325,00
C1255,50 ct/cm331,25

The concentration determines the price on the one hand and the overall grinding behaviour of the disc on the other hand.

Picard tip:

  • Higher concentrations (C100-C125-C150 / V240-V360) are appropriate when high profile retention, narrow covering widths, high bond hardness and deep grinding are required.
  • Medium concentrations (C50-C75 / V120-V180) are recommended for cup wheels and peripheral wheels with larger lining widths and finer grain sizes.
  • Low concentrations (C38-C50 / V120) are primarily used for very fine grain sizes.

Grain

The selection of CBN grain sizes is decisive for the stock removal rate and the resulting cutting results and surface qualities. The service life of the abrasive tool is also influenced by the abrasive grain size. Due to the large selection of synthetically produced abrasive grains in combination with the different bond types, the quality of the abrasive tool can be optimally adapted to your grinding operation.

For synthetic resin bonded abrasive tools, nickel coated abrasive grains are mainly used. Special coating processes enable adhesion possibilities in the bond, which also improve the thermal conductivity (see table of grit sizes below). In order to meet the various grinding requirements, there are a large number of grain sizes which have been combined into one standard by the FEPA (Fédération Européene des Fabricants de Produits Abrasifs).

The same grain sizes apply to diamond and CBN. Diamond grains are identified by a D (e.g. D126), CBN grains by a B (e.g. B126).

GrainDiamondCBN
coarselyD251B251
D181B181
D151B151
mediumD126B126
D107B107
D91B91
D76B76
D64B64
fineD54B54
D46B46
very fineD15B15
D7B7
D3B3

The grain size determines both the stock removal rate of CBN grinding wheels and the surface quality that can be achieved on the workpiece. The higher stock removal rate is generally achieved with coarser grit sizes. Finer grits improve the grinding quality, but at the same time reduce the stock removal rate.

Cutting speeds

The cutting speed of the CBN grinding tool has a very large influence on the service life, grinding performance and surface quality of the workpiece to be ground. The values listed below are guide values for setting the cutting speed:

Resin bondDiamondCBN
dry grinding12 - 18 m/s16 - 22 m/s
wet grinding25 - 30 m/s25 - 30 m/s

Forms

The selection of CBN grain sizes is decisive for the stock removal rate and the resulting cutting results and surface qualities. The service life of the abrasive tool is also influenced by the abrasive grain size. Due to the large selection of synthetically produced abrasive grains in combination with the different bond types, the quality of the abrasive tool can be optimally adapted to your grinding operation.

For synthetic resin bonded abrasive tools, nickel coated abrasive grains are mainly used. Special coating processes enable adhesion possibilities in the bond, which also improve the thermal conductivity (see table of grit sizes below). In order to meet the various grinding requirements, there are a large number of grain sizes which have been combined into one standard by the FEPA (Fédération Européene des Fabricants de Produits Abrasifs).

The same grain sizes apply to diamond and CBN. Diamond grains are identified by a D (e.g. D126), CBN grains by a B (e.g. B126).

shapeDXTHgrainconcentrationtie
1 A11004620B126C75K20N
shapeDXVTHgrainconcentrationtie
1 V1100360°1220B91C100K7010
shapeDXRUHgrainconcentrationtie
14 F11002,52432B91C100K20R
shapeVDUXHgrainconcentrationtie
14 EE160°1254420B64C75K20R
shapeDWXHgrainconcentrationtie
4 A21255220B91C75K20R
shapeDWXTHgrainconcentrationtie
4 BT91001011032B64C75K20R
shapeDWXHgrainconcentrationtie
6A212512,5220B126C50K20R
shapeDWXHgrainconcentrationtie
6A910031025B126C75K20R
shapeDWXHgrainconcentrationtie
11A21008220B64C50K20R
shapeDWXHgrainconcentrationtie
12A2-45°10010420B64C50K20R