As a dedicated manufacturer of precision cutting tools, we understand that stability and wear resistance are non-negotiable. This article analyzes the application of our CBN inserts in hard turning, based on a typical case study from one of our Indian customers.
Case Study: Machining 62-65 HRC Steel
The following parameters outline a challenging application where our CBN solution successfully replaced a grinding operation.
1. Processing Conditions
●Machining Method: Precision Internal Turning (Boring)
●Workpiece Material: Quenched and Tempered Steel (Hardened Steel)
●Hardness Range: 62 – 65 HRC
●Target Bore Diameter: Ø5.93 – 5.95 mm
●Dimensional Tolerance: ±10 μm
●Bore Depth: 30 mm
●Depth of Cut (ap): 0.06 mm (Single side)
●Insert Solution: CCMW030104 CBN525
●Tool Holder: Carbide Boring Bar (C05H-SCLCL03-06AN)
The Challenge: This scenario represents a typical combination of "Small Bore + Ultra-High Hardness + Micro-Finishing Allowance." It demands exceptional tool strength, wear resistance, and cutting stability.
2. Why CBN is Essential for this Application
When material hardness exceeds 58 HRC, traditional carbide tools fail. They suffer from plastic deformation at the cutting edge, severe flank wear, and dimensional drift.
Our CBN inserts offer distinct advantages:
●Extreme Hot Hardness: Maintains hardness even at temperatures exceeding 1000°C.
●Superior Wear Resistance: Several times more durable than carbide.
●Chemical Stability: Low affinity to iron reduces the risk of Built-Up Edge (BUE), ensuring stable, continuous machining.
3. Key Technical Challenges in Small Bore Hard Turning
Machining a Ø6mm hole in 65 HRC steel presents three specific hurdles:
1. Low Rigidity: Small diameter boring bars are prone to vibration (chatter), which can lead to ovality errors and surface waviness.
2. Micro-Depth Cutting: With an ap of only 0.06 mm, the tool must cut cleanly. If the edge is not sharp or rigid enough, it will "rub" instead of cut, generating heat and poor surface finish.
3. Strict Tolerance Control: Achieving ±10 μm requires predictable tool wear patterns. Any chipping or thermal deformation will cause the part to go out of tolerance immediately.
4. Process Advantages of Our CBN Solution
By switching to our CBN525 grade, the customer achieved:
●System Stability: Reduced fluctuation in cutting forces minimizes vibration in the slender boring bar.
●Predictable Life: Linear wear patterns make tool compensation management easy and reliable.
●Grinding-Level Finish: The surface roughness (Ra) achieved rivals that of grinding processes.
●Efficiency: Replacing grinding with turning reduces setup times and eliminates errors caused by re-clamping.
5. Product Highlight: The CCMW Negative Rake Advantage
For this specific application, the CCMW030104 insert is the optimal choice.
●Small Size: perfectly suited for micro-boring applications.
●Negative Rake Geometry: Enhances the strength of the cutting edge. This is crucial for withstanding the high impact loads of machining 60+ HRC materials without chipping.
●Carbide Boring Bar Synergy: Paired with the C05H carbide shank, the system rigidity is maximized to prevent deflection.
Conclusion
In scenarios where high hardness, small diameters, micro-allowances, and high precision coexist, CBN tooling is the core element for guaranteeing production stability and consistency.
Ready to optimize your hard turning process?
Contact us today to learn more about our CCMW series and other high-performance CBN solutions designed for hardened steel applications.
