When machining materials above 45 HRC or heat-resistant superalloys, conventional carbide inserts reach their thermal and mechanical limits rapidly. Tungaloy’s CBN (cubic boron nitride) and ceramic grade platforms are engineered specifically for these extreme conditions, delivering tool life and surface integrity that coated carbide cannot achieve. This guide provides a complete parameter reference for Tungaloy’s CBN and ceramic turning grades across ISO H (hardened steel), ISO S (superalloys and titanium), and ISO K (hard cast iron) applications.
Tungaloy CBN Grade Platform Overview
Tungaloy offers two primary CBN substrate families: BoraProtect (BXA series) for continuous to light interrupted cutting of hardened steel, and BestForce (BXC series) for heavy interrupted and forged surface machining. The distinction lies in CBN content, binder phase, and edge preparation strategy.
BoraProtect BXA Series
The BXA series features high CBN content (above 90%) with a ceramic binder phase, providing excellent thermal conductivity and wear resistance for continuous hard turning operations. The grades include:
- BXA20 — General-purpose CBN for hardened steel (55–65 HRC), optimized for continuous turning and finishing operations
- BXA10 — Higher CBN content variant for improved surface finish in precision hard turning applications
- BXA30 — Tougher substrate for light interrupted cuts in hardened components
BestForce BXC Series
The BXC series uses a lower CBN content (60–70%) with a metallic cobalt binder, delivering superior fracture toughness for interrupted and scalping operations:
- BXC50 — For medium to heavy interrupted turning of hardened steel (50–62 HRC)
- BXC70 — Optimized for forged and cast surface machining with significant interruptions
- BXC90 — Maximum toughness for severe interrupted cutting and scale removal
Tungaloy Ceramic Grade Platform
Tungaloy ceramic turning grades cover silicon nitride (Si₃N₄), alumina-based (Al₂O₃), and whisker-reinforced compositions. Each family targets specific thermal and chemical wear mechanisms.
- TQ10 — Mixed alumina ceramic for hard steel turning (45–55 HRC) and heat-resistant alloys
- NS9520 — SiAlON ceramic for nickel-based superalloys and high-temperature alloy machining
- LX10 — Whisker-reinforced ceramic (Al₂O₃ + SiC whiskers) for nickel-based alloys requiring high fracture resistance
- TS10 — Silicon nitride for gray and ductile cast iron high-speed machining
CBN Turning Parameters for Hardened Steel (ISO H)
Hard turning of steel components in the 45–65 HRC range is the primary application for Tungaloy CBN inserts. The following parameter tables provide starting values for continuous and interrupted cutting conditions.
BXA20 — Continuous Hard Turning (55–65 HRC)
| Operation | Vc (m/min) | fn (mm/rev) | ap (mm) | Edge Prep |
|---|---|---|---|---|
| Finishing | 120–180 | 0.05–0.15 | 0.1–0.5 | T-land 0.10×20° |
| Semi-finishing | 100–150 | 0.10–0.25 | 0.3–1.0 | T-land 0.15×25° |
| Roughing (light) | 80–120 | 0.15–0.30 | 0.5–2.0 | T-land 0.20×30° |
BXC50 — Interrupted Hard Turning (50–62 HRC)
| Operation | Vc (m/min) | fn (mm/rev) | ap (mm) | Edge Prep |
|---|---|---|---|---|
| Finishing | 80–120 | 0.08–0.15 | 0.1–0.5 | T-land 0.15×25° |
| Semi-finishing | 70–100 | 0.10–0.20 | 0.3–1.5 | T-land 0.20×30° |
| Roughing (interrupted) | 60–90 | 0.15–0.25 | 0.5–2.0 | T-land 0.25×30° |
Ceramic Turning Parameters for Superalloys (ISO S)
Nickel-based superalloys such as Inconel 718, Waspaloy, and Hastelloy present extreme machining challenges due to work hardening, thermal conductivity below 15 W/m·K, and high shear zone temperatures. Tungaloy’s SiAlON (NS9520) and whisker-reinforced (LX10) ceramics enable cutting speeds 5–10 times higher than carbide alternatives.
NS9520 SiAlON — Inconel 718 (Solution Treated + Aged)
| Operation | Vc (m/min) | fn (mm/rev) | ap (mm) | Coolant |
|---|---|---|---|---|
| Roughing | 150–250 | 0.15–0.30 | 1.0–3.0 | Dry |
| Semi-finishing | 200–300 | 0.10–0.20 | 0.5–1.5 | Dry |
| Finishing | 250–350 | 0.05–0.12 | 0.2–0.8 | Dry |
LX10 Whisker-Reinforced — Waspaloy and Hastelloy X
| Operation | Vc (m/min) | fn (mm/rev) | ap (mm) | Coolant |
|---|---|---|---|---|
| Roughing | 120–200 | 0.12–0.25 | 0.8–2.5 | Dry |
| Finishing | 180–280 | 0.05–0.15 | 0.2–1.0 | Dry |
Critical note: Ceramic turning of superalloys must be performed dry. Coolant application causes thermal shock and catastrophic insert fracture. Ensure adequate chip evacuation and machine guarding, as ceramic inserts generate high-temperature chips that can reach 600°C at the cutting zone.
CBN vs Ceramic Grade Selection Matrix
Choosing between CBN and ceramic grades depends on workpiece hardness, surface integrity requirements, and cutting condition continuity. The following comparison matrix provides clear selection criteria.
| Parameter | BXA20 (CBN) | BXC50 (CBN) | NS9520 (SiAlON) | LX10 (Whisker) |
|---|---|---|---|---|
| Material Group | ISO H (55–65 HRC) | ISO H (50–62 HRC) | ISO S (Ni-alloys) | ISO S (Ni/Co-alloys) |
| Max Vc (m/min) | 180 | 120 | 350 | 280 |
| Feed Range (mm/rev) | 0.05–0.30 | 0.08–0.25 | 0.05–0.30 | 0.05–0.25 |
| Max ap (mm) | 2.0 | 2.0 | 3.0 | 2.5 |
| Interrupted Cut | Light only | Medium to heavy | Light only | Light to medium |
| Coolant | Dry or air | Dry | Dry only | Dry only |
| Surface Finish Ra (µm) | 0.2–0.6 | 0.4–1.2 | 0.8–2.0 | 0.6–1.5 |
| Thermal Shock Resist. | Moderate | High | Low | Moderate |
Hard Cast Iron Machining with CBN (ISO K)
Hardened cast iron components such as rolls, camshafts, and valve seats require abrasion-resistant cutting materials. Tungaloy CBN grades excel in these applications due to their chemical inertness with iron and superior hot hardness.
BXA10 — Hard Cast Iron (Hardened to 55–60 HRC)
| Material | Vc (m/min) | fn (mm/rev) | ap (mm) | Expected Tool Life |
|---|---|---|---|---|
| Hardened cast iron rolls | 100–150 | 0.10–0.25 | 0.3–1.5 | 20–40 min |
| Chilled cast iron | 80–120 | 0.08–0.20 | 0.2–1.0 | 15–30 min |
| Ni-Hard iron | 60–100 | 0.08–0.15 | 0.2–0.8 | 10–25 min |
Competitive Comparison: Tungaloy vs Sumitomo CBN Grades
Both Tungaloy and Sumitomo are leading CBN insert manufacturers with distinct substrate philosophies. Sumitomo’s BNX series competes directly with Tungaloy’s BXA/BXC platforms. The table below compares equivalent grades and their performance characteristics.
| Tungaloy Grade | Sumitomo Equivalent | CBN Content | Binder | Strength Advantage |
|---|---|---|---|---|
| BXA20 | BNX20 | 90%+ (high) | Ceramic | Wear resistance (Tungaloy) |
| BXC50 | BNX50 | 65% (medium) | Metallic | Toughness (comparable) |
| BXC70 | BNX70 | 60% (lower) | Metallic | Interrupted cut (Sumitomo edge) |
| NS9520 (SiAlON) | SX7 (SiAlON) | N/A | N/A | Notch wear resist. (Tungaloy) |
Tungaloy’s BXA20 demonstrates approximately 10–15% better flank wear resistance in continuous hard turning due to its optimized ceramic binder composition. However, Sumitomo’s BNX70 shows marginally better performance in heavy interrupted conditions thanks to its proprietary edge honing geometry. For SiAlON ceramic applications, Tungaloy’s NS9520 provides superior notch wear resistance on Inconel 718, extending tool life by 15–20% compared to competitive SiAlON grades in long-run finishing operations.
Edge Preparation and Geometry Guidelines
The success of CBN and ceramic turning depends heavily on edge preparation. Tungaloy offers standardized T-land (chamfer) and hone combinations that must be matched to the cutting condition:
- Light finishing (ap < 0.3mm): T-land 0.08–0.10mm × 20°, light hone. Prioritizes surface finish and dimensional accuracy.
- Standard finishing (ap 0.3–1.0mm): T-land 0.15mm × 25°, medium hone. Balanced wear and toughness performance.
- Roughing (ap 1.0–2.0mm): T-land 0.20–0.25mm × 30°, heavy hone. Maximizes impact resistance for deeper cuts.
- Interrupted cutting: T-land 0.25mm × 30° with reinforced hone, negative land geometry. Only BXC series or LX10 grades recommended.
Insert Geometry Recommendations
| Application | Insert Shape | Rake Angle | Clearance | Nose Radius |
|---|---|---|---|---|
| CBN hard finishing | CNGA (80° diamond) | -5° | 5° | 0.4–0.8mm |
| CBN hard roughing | SNGA (square) | -5° | 5° | 0.8–1.2mm |
| SiAlON superalloy | RNGA (round) | -5° to -7° | 5° | R6–R12mm |
| Whisker ceramic | RNGA (round) | -5° | 5° | R4–R8mm |
Tool Life Expectancy and Wear Patterns
Understanding expected tool life and dominant wear modes helps operators optimize parameters and replacement intervals. The following data represents typical performance under recommended cutting conditions.
| Grade | Workpiece | Vc (m/min) | Tool Life (min) | Dominant Wear |
|---|---|---|---|---|
| BXA20 | SKD11 (60 HRC) | 150 | 25–35 | Flank wear |
| BXA20 | SUJ2 (62 HRC) | 120 | 30–45 | Flank + crater |
| BXC50 | SKD61 (50 HRC, interrupted) | 80 | 15–25 | Edge chipping |
| NS9520 | Inconel 718 (40 HRC) | 250 | 8–15 | Notch wear |
| LX10 | Waspaloy (35 HRC) | 200 | 10–18 | Notch + flank |
Practical Application Notes
- Machine rigidity: CBN and ceramic turning requires machine tools with spindle runout below 5µm and minimal structural deflection. Insufficient rigidity causes micro-chipping and premature insert failure.
- Workpiece entry/exit: Reduce feed rate by 50% during the first 1–2mm of entry and last 1mm of exit to prevent edge fracture at the cut transition points.
- Coolant strategy: CBN grades tolerate light coolant application (flood at 5–10 bar) for chip evacuation, but ceramic grades require completely dry cutting. Air blast at 4–6 bar is the preferred chip removal method for ceramic operations.
- Surface speed limits: Exceeding the maximum recommended cutting speed causes rapid crater formation on CBN grades and thermal softening of ceramic edges. Maintain speeds within the specified ranges and verify with spindle speed calculations for the actual workpiece diameter.
- Nose radius selection: Smaller nose radii (0.4mm) produce better surface finishes in finishing operations but reduce edge strength. For interrupted cuts, increase to 0.8mm minimum and pair with BXC series grades.
Summary
Tungaloy’s CBN and ceramic grade platforms provide comprehensive solutions for hard turning and superalloy machining applications. The BXA series excels in continuous hard turning of 55–65 HRC steels with cutting speeds of 120–180 m/min, while the BXC series handles interrupted conditions up to 50–62 HRC. For nickel-based superalloys, NS9520 SiAlON ceramics achieve cutting speeds of 250–350 m/min — a 5–10× improvement over carbide. By matching the correct grade, edge preparation, and cutting parameters to the specific application, manufacturers can achieve consistent surface finishes below Ra 0.6µm and tool life exceeding 30 minutes in hardened steel operations. Always verify parameters against specific workpiece conditions and perform test cuts before full production implementation.
Shop Related Products at HOOGUU
