CBN Inserts for Hard Turning Hardened Steel
Select CBN and PCBN inserts for hardened steel, bearing steel, case-hardened parts, continuous finishing and interrupted hard turning. Match the grade, insert geometry, edge preparation and cutting condition to the required tool life and surface finish.
Hard Turning Applications by Steel Type
The material condition, hardened layer and interruption level influence grade and geometry selection.
Hardened Bearing Components
Finish races, shafts and hardened functional surfaces with stable geometry and wear-focused grades.
Case-Hardened Parts
Match the cutting edge to the hardened case, component geometry and possible transitions into softer core material.
Hardened Tool and Die Steel
Use application-matched PCBN grades for stable finishing or interrupted surfaces in hardened tool steels.
Through-Hardened Components
Review hardness, stock allowance, setup rigidity and continuity of cut before selecting the grade and insert body.
Choose CBN Inserts by Hard-Turning Condition
As interruption increases, selection moves from wear-focused grades toward tougher grades and more stable edge conditions.
Prioritize wear resistance, dimensional consistency and surface finish in stable cuts.
Balance abrasion resistance and toughness for small holes, shallow keyways or periodic interruption.
Use tougher grade direction, stable insert geometry and appropriate edge preparation where impact dominates.
PCBN Grades for Hard Turning
Use the grade table as a starting point, then confirm availability for the selected insert code and structure.
| Grado | CBN Content | Best-Fit Condition | Hard-Turning Direction |
|---|---|---|---|
| OBN45 | Approx. 45% | De continuo a moderadamente interrumpido | Finish hard turning, high speed and fine surface finish |
| OBC50 | Approx. 50% | De continuo a ligeramente interrumpido | General hard machining and cold-work tool steel |
| O2C50 | Approx. 50% | De continuo a ligeramente interrumpido | Higher-speed hard machining with abrasion resistance |
| OBX60 / OBX65 | Aprox. 65% | Moderate to heavy interruption | Hardened steel requiring greater toughness |
| OBW85 | Approx. 85% | Heavy interruption and abrasive conditions | Use where chip resistance and toughness become more important |
Confirm the final commercial naming of OBX60/OBX65 before publishing.
CBN Cutting Parameters for Hardened Steel
Use these values as starting ranges. Final speed, feed and depth of cut must be adjusted to the selected PCBN grade, insert geometry, hardness, interruption level and machine rigidity.
| Funcionamiento | Cutting Condition | Velocidad de corte Vc | Profundidad de corte ap | Feed f |
|---|---|---|---|---|
| Turning / Roughing | Continuous cutting | 80–160 m/min | 1.0–2.5 mm | 0.1–0.5 mm/rev |
| Turning / Roughing | Interrupted cutting | 80–125 m/min | 1.0–2.5 mm | 0.1–0.5 mm/rev |
| Torneado final | Continuous cutting | 125–210 m/min | 0,1–0,5 mm | 0,05–0,2 mm/rev |
| Torneado final | Interrupted cutting | 100–150 m/min | 0,1–0,5 mm | 0,05–0,2 mm/rev |
| High-Alloyed Steel Roughing | General turning | 60–110 m/min | 0.5–2.0 mm | 0.15–0.3 mm/rev |
| High-Alloyed Steel Finishing | Final turning | 80–150 m/min | 0,1–0,5 mm | 0,05–0,2 mm/rev |
Start from the lower half of the range for a new setup, unstable clamping or interrupted surfaces. Increase one parameter at a time after confirming edge condition and surface finish.
Choose the Insert Shape for the Hard-Turning Cut
Geometry selection depends on component access, insert strength, holder style and required profile.
| Geometry Direction | Representative Families | Uso típico |
|---|---|---|
| Stable general turning | CNGA, SNGA, WNGA | External diameters, facing and stable hard finishing |
| Profiling and shoulder access | DNGA, VNGA | Contours, tapers and restricted approach |
| Multi-corner turning | TNGA, WNGA | General turning where usable corner count is important |
| Lower-force / internal turning | CCGW, DCGW, TCGW, VCGW | Boring, profiling and lighter cutting-force requirements |
Common Hard-Turning Tool-Life Problems
Review the failure mode before changing grade, geometry or cutting data.
Desgaste rápido de los flancos
Review cutting speed, stock consistency, grade wear resistance and edge engagement.
Desgaste de los bordes
Check interruption level, setup rigidity, edge preparation and grade toughness.
Mal acabado superficial
Review nose radius, feed, vibration, workpiece support and accumulated edge wear.
Dimensional Variation
Check machine stability, thermal effects, insert seating and progressive wear.
How Nose Radius and Feed Affect Hard-Turning Finish
The theoretical surface profile is influenced by feed per revolution and cutting-edge radius. Actual finish can still be limited by vibration, clamping, tool wear and workpiece instability.
The formula estimates theoretical surface roughness from feed and nose radius.
| Target Ra | Rt | r = 0.2 | r = 0.4 | r = 0.8 | r = 1.2 | r = 1.6 |
|---|---|---|---|---|---|---|
| 0.8 | 1.8 | 0.05 | 0.07 | 0.10 | 0.12 | 0.14 |
| 1.6 | 4.0 | 0.08 | 0.11 | 0.15 | 0.19 | 0.23 |
| 3.2 | 10.0 | 0.12 | 0.17 | 0.24 | 0.29 | 0.36 |
| 6.3 | 16.0 | 0.16 | 0.22 | 0.30 | 0.37 | 0.45 |
Table values are feed f in mm/rev. The theoretical calculation does not include unstable machining conditions, insufficient machine or workpiece rigidity, incorrect clamping, tool wear or variable depth of cut.
Information Needed for a Hard-Turning Recommendation
Accurate selection requires the actual workpiece condition and current process result, not only the insert code.
CBN Inserts for Hard Turning: Common Questions
Why are CBN inserts used for hard turning?
CBN and PCBN inserts combine high hot hardness and wear resistance, making them suitable for turning hardened steels and selected abrasive materials where carbide may wear too quickly.
Which PCBN grade is suitable for continuous hard turning?
Wear-focused lower-CBN grades are commonly selected for stable finishing. The final grade depends on hardness, speed, stock consistency, required finish and insert-code availability.
Which grade should I use for interrupted hard turning?
As interruption increases, a tougher grade and more stable geometry are generally required. Edge preparation, setup rigidity and actual impact level also affect the choice.
Can CBN inserts turn case-hardened steel?
Yes, provided the hardened layer, hardness range, stock allowance and transition into softer material are considered when selecting the grade and cutting edge.
Which insert shape is best for hard turning?
C, S and W shapes offer stable cutting bodies, while D and V shapes improve profile access. The best shape depends on holder style, component geometry and interruption level.
How do I improve surface finish in hard turning?
Review nose radius, feed, machine rigidity, insert seating, edge wear and component support. A grade change alone may not solve vibration or geometry-related finish problems.
What information is needed for a hard-turning quotation?
Provide the insert code, material, hardness, cutting condition, current cutting data, tool life, surface-finish target and required quantity.
Send Your Hard-Turning Application
Share the material, hardness, insert code and current process. Our team will review the PCBN grade, geometry and quotation.
- Material y dureza de la pieza de trabajo
- Continuous or interrupted cutting condition
- Insert and holder code
- Cutting speed, feed and depth of cut
- Current tool life and failure mode
- Required quantity and target result
