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Turning tools \ Technical introduction – CBN turning

Hard machining process with CBN

Cutting hardened steel is referred to as hard cutting. By introducing energy in the form of cutting speed
vc, feed f, depth of cut ap and different cutting edges = chamfer, self-induced hot cutting is produced. This

requires a defi ned high temperature of approx. 550 to 750° C in the shear zone. Cooling is not required for
this process.
To generate and maintain the ideal cutting temperature in the shear zone, the following must be observed:
 Selection of appropriate cutting material for different materials,

 Determination of appropriate bevel geometry A-H
 Identifi cation of cutting speed in event charts (hardness diagram with increasing temperature)
The following points must be noted:
 Exact specifi cation of the type of steel and its hardness in HRC.
 Required surface quality Ra in µm as well as cutting depth.
 Machining conditions smooth, slightly interrupted or severely interrupted cut

Selection of the cutting material types when machining with PCBN

We distinguish between materials based on the concentration of CBN content. In the case of a high CBN content, materials such as cast iron, special alloys and
sintered steels can be machined. For hard machining, the CBN content must be reduced.
A distinction is made between the following cutting materials:
Coating CBN content
100 90 80 70 60 50 40 30 20 10
uncoated ABC-10

uncoated ABC-25

uncoated ABC-40

coated ABC-10B

coated ABC-25B

coated ABC-40B

CBN grades, uncoated: CBN grades, coated:
ABC-10 ABC-10B
 Uncoated CBN type with very high CBN content (95%) for application in grey  CBN cutting material coated with 95% CBN content for application in grey cast
cast iron, special alloys, sintered steels iron (GG20-GG40) and special alloys such as Inconell 718, Nicomic, Hastelloy,
 Fine grain 1-1.5 m Waspaloy
 Application both in favourable conditions (smooth cut) and unfavourable condi-  Fine grain (1-1.5 µ)
tions (non-continuous cut) ap = 0.1-0.7 mm  Application both in favourable conditions (smooth cut) and unfavourable condi-
tions (non-continuous cut) ap = 0.1-0.7 mm
ABC-25
 Uncoated CBN type with low CBN content (65%) in hard cutting, dry + wet from ABC-25B
HRC 52 - 65  CBN cutting material coated with 65% CBN content for application in hard
 Fine grain (3 m) machining 48-62 HRC (wet-dry)
 Application in favourable conditions (smooth cut) and very lightly interrupted  Fine grain (1 - 2µ)
cutting ap = 0.05 - 0.4 mm  Application in favourable conditions (smooth cut) ap = 0.02 - 0.4 mm
ABC-40 ABC-40B
 Uncoated CBN type with low CBN content (65%)  CBN cutting material coated with 55% CBN content for application in hard
 Hard machining, dry + wet from HRC 54 - 65 machining 48-62 HRC (wet-dry)
 Application in unfavourable conditions for lightly and heavily interrupted cutting  Superfi ne grain (0.75 µ)
ap = 0.05 - 0.4 mm  Application in unfavourable conditions for lightly and heavily interrupted cutting
ap = 0.05-0.4 mm

Source: Hahn+Kolb Werkzeuge GmbH
Technical data subject to change. www.iconridge.com
Availability subject to country specific rules and regulations. 293

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