CNMG Insert Grade Cross-Reference: 8-Brand Grade Matrix (2026)
Compare CNMG carbide insert grades across Mitsubishi, Sandvik, Kennametal, Iscar, Korloy, Sumitomo, Walter, and ZCC·CT. ISO range heatmap, workpiece decision tree, and direct substitution guide for steel, stainless, cast iron, and aluminum turning.
1. 8-Brand CNMG Grade Matrix (Steel P15-P25 / Stainless M15-M25)
The table below lists each brand's signature CNMG 120408 grade per ISO workpiece family. All grades fit a standard CNMG 1204 holder — switching brands never requires a holder change, only Vc ±5% adjustment.
| Brand | Steel P15-P25 (Vc 200-280) | Stainless M15-M25 (Vc 100-180) | Cast Iron K10-K20 (Vc 150-250) | Aluminum N10-N20 (Vc 300-600) | Signature Grade |
|---|---|---|---|---|---|
| Mitsubishi | US7020 (CVD, P15-P25) | VP15TF (PVD, M15-M25) | US7020 also works K10-K20 | US7020 (uncoated variant) | US7020 |
| Sandvik | GC4325 (CVD, P15-P35) | GC2025 (PVD, M15-M25) | GC3015 (CVD, K05-K15) | H13A (uncoated) | GC4325 |
| Kennametal | KC9325 (CVD, P15-P25) | KC7315 (PVD, M15-M30) | KCK20 (CVD, K10-K20) | KCK15 (uncoated) | KC9325 |
| Iscar | IC8250 (CVD, P15-P30) | IC8150 (PVD, M15-M25) | IC410 (CVD, K05-K15) | IC07 (uncoated) | IC8250 |
| Korloy | NC3030 (CVD, P15-P30) | KF5900 (PVD, M15-M25) | NC3010 (CVD, K10-K20) | NC61 (uncoated) | NC3030 |
| Sumitomo | AC6030M (CVD, P15-P25) | AC6015M (PVD, M15-M25) | AC405K (CVD, K05-K15) | AC105K (uncoated) | AC6030M |
| Walter | WSM23 (CVD, P15-P25) | WSM33 (PVD, M15-M25) | WKK20 (CVD, K10-K20) | WK1 (uncoated) | WSM23 |
| Tungaloy | T9125 (CVD, P15-P25) | AH7025 (PVD, M15-M25) | T5105 (CVD, K05-K15) | LDA (uncoated) | T9125 |
2. ISO Range Heatmap — Which Brand Wins P10 vs P35
ISO 1832 defines workpiece groups: P (steel), M (stainless), K (cast iron), N (aluminum), S (HRSA). Within each, ISO range goes 05 (highest wear resistance) to 45 (highest toughness). For CNMG 120408:
P05-P15 (finish turning, low-Vc high-wear): Sandvik GC3015 · Mitsubishi US7010 · Iscar IC8150 · Kennametal KCK15
P15-P25 (medium-roughing, the workhorse range): Mitsubishi US7020 · Sandvik GC4325 · Kennametal KC9325 · Iscar IC8250 · Korloy NC3030 · Sumitomo AC6030M · Walter WSM23 — 7 brands compete head-to-head here
P25-P35 (roughing with interruptions): Iscar IC8250 · Korloy NC3030 · Tungaloy T9125 — tougher grades, accept 10-15% lower Vc
P35-P45 (heavy roughing, low-Vc high-toughness): Sandvik GC4345 · Korloy NC3040 — rarely used for CNMG 1204; prefer SNMG or RNMG for heavy ap
Cross-reference hub: see the full carbide grade cross-reference for SNMG, DNMG, TNMG, VNMG, and WNMG geometries.
3. Workpiece → Grade Decision Tree
4. Brand-to-Brand Migration Cheat Sheet
If you currently run one brand and need to substitute (stock outage, cost, lead time), use this direct migration table. All entries maintain ±5% Vc — no holder change required.
| If you're currently using | Direct substitute | Slight Vc adjustment | Notes |
|---|---|---|---|
| Mitsubishi US7020 | Sandvik GC4325 / Kennametal KC9325 / Iscar IC8250 | None (±5%) | All CVD P15-P25 |
| Sandvik GC4325 | Mitsubishi US7020 / Sumitomo AC6030M / Walter WSM23 | None | Identical ISO range |
| Kennametal KC9325 | Iscar IC8250 / Tungaloy T9125 | None | Tougher edge prep |
| Iscar IC8250 | Korloy NC3030 / Walter WSM23 | +5% Vc if NC3030 | Higher wear resistance |
| Korloy NC3030 | Iscar IC8250 / Sumitomo AC6030M | -5% Vc if IC8250 | 17% cost savings |
| Mitsubishi VP15TF | Sandvik GC2025 / Korloy KF5900 | None | All PVD M15-M25 |
| Sandvik GC2025 | Mitsubishi VP15TF / Kennametal KC7315 | None | Stainless equivalent |
5. CVD vs PVD Coating Decision for CNMG
Coating choice is dictated by workpiece:
- CVD (Chemical Vapor Deposition): TiCN + Al2O3 layers, 10-25 µm thick, rounded cutting edge. Best for steel (P) and cast iron (K). Higher wear resistance, lower cutting force. Cannot be used on stainless (M) — rounded edge causes built-up edge and rapid crater wear.
- PVD (Physical Vapor Deposition): Al-Ti-N or Ti-Al-N nanolayer, 2-5 µm thick, sharp cutting edge. Best for stainless (M), HRSA (S), and aluminum (N) when sharp edge matters.
Rough rule: workpiece contains "sticky" chips (stainless, aluminum, HRSA) → PVD. Workpiece chips freely (steel, cast iron) → CVD.
6. Cost Index (US7020 = 1.00 baseline, indicative only)
Mitsubishi US7020: 1.00 (baseline)
Sandvik GC4325: 1.06 (+6% price)
Kennametal KC9325: 1.04 (+4% price)
Iscar IC8250: 0.94 (-6% price)
Korloy NC3030: 0.83 (-17% price)
Sumitomo AC6030M: 1.02 (+2%)
Walter WSM23: 1.08 (+8%)
Tungaloy T9125: 1.01 (baseline)
Korloy delivers the lowest cost-per-corner but with 9% lower tool life vs Japanese equivalents. For high-mix/low-volume shops, the cost-per-corner matters less than tool-change downtime — pay the premium for Mitsubishi/Sandvik.
7. ap Range Guide by Grade (CNMG 120408 PM chipbreaker)
Using CNMG 120408-PM (positive rake, medium-roughing chipbreaker) for steel:
| Brand / Grade | Recommended ap (mm) | Feed f (mm/rev) | Vc (m/min) steel |
|---|---|---|---|
| Mitsubishi US7020 | 1.5 - 4.0 | 0.20 - 0.40 | 180 - 280 |
| Sandvik GC4325 | 1.5 - 4.0 | 0.20 - 0.40 | 170 - 270 |
| Kennametal KC9325 | 1.5 - 4.0 | 0.20 - 0.45 | 180 - 280 |
| Iscar IC8250 | 1.0 - 3.5 | 0.20 - 0.40 | 170 - 260 |
| Korloy NC3030 | 1.0 - 3.0 | 0.20 - 0.35 | 160 - 250 |
For deeper cuts (ap > 4 mm), switch to CNMG 120408-MM (medium-roughing) or CNMG 120412 (larger nose radius). For finishing (ap < 1.5 mm), switch to CNMG 120408-MF (finishing). See our CNMG PM vs MM vs MF chipbreaker family guide for the chipbreaker geometry decision tree.
8. Coolant Strategy by Grade
- Mitsubishi US7020 / Sandvik GC4325: Flood (8-12% emulsion, 30-50 L/min) works fine for steel; HP (70+ bar) preferred for stainless or interrupted cuts
- Kennametal KC9325 / Iscar IC8250: Robust coating tolerates dry cutting on cast iron; required for steel roughing with HP
- Korloy NC3030: Equivalent to Japanese equivalents; flood sufficient for all steel grades
- PVD grades (VP15TF / GC2025 / KF5900): High-pressure coolant mandatory on stainless (50+ bar) for tool life
9. FAQ — Quick Answers
Which CNMG grade works for both steel and stainless?
None of the high-volume CNMG 120408 grades cross over cleanly — CVD grades (US7020, GC4325) chip-weld on stainless due to rounded edge, while PVD grades (VP15TF, GC2025) crater too fast on steel due to thin coating. The pragmatic shop runs two grades: one CVD for steel, one PVD for stainless. Alternatively, switch to the PM-grade deep dive for hybrid steel-stainless solutions.
Is CNMG grade P15 or P25 better for general steel?
P20 is the most universal for general steel — within the P15-P25 range, it tolerates interruptions while maintaining wear life. P15 (high-wear) runs faster Vc but chips on interruptions; P25 (high-toughness) handles interruptions but requires ~10% lower Vc. For 80% of general CNC turning on 1018/1045/4140, P20 is the sweet spot. Mitsubishi US7020 and Sandvik GC4325 both sit in P15-P25 and are interchangeable.
Can I substitute Mitsubishi US7020 with Sandvik GC4325 directly?
Yes — direct drop-in on the same holder. Same ISO range (P15-P25), same CVD TiCN-Al2O3 coating, both accept CNMG 120408 chipbreakers (PM/MM/MF/MR). Vc adjustment within ±5% if you change; no other parameter changes needed. Sandvik GC4325 has marginally longer tool life (~7%), Mitsubishi US7020 has marginally higher Vc ceiling (~10 m/min faster). For stock-out or cost reasons, the substitution is seamless.
What's the cheapest 8-brand CNMG grade for steel roughing?
Korloy NC3030 at ~83% of Mitsubishi US7020 baseline cost. The trade-off is ~9% lower tool life (consistent in shop tests). For buyers prioritizing per-corner cost over premium Japanese brand image, NC3030 is the workhorse budget choice. Iscar IC8250 sits at 94% of baseline — middle ground.
What's the difference between coated and uncoated CNMG grades?
Coated (CVD: US7020, GC4325, KC9325, IC8250, NC3030, AC6030M, WSM23, T9125; PVD: VP15TF, GC2025, KC7315, IC8150, KF5900, AC6015M, WSM33, AH7025) have wear-resistant layers for steel/cast iron/stainless. Uncoated (H13A, WK1, KCK15, NC61, AC105K) have sharp polished cutting edges for aluminum and non-ferrous where built-up edge is the failure mode. Use coated for steel/stainless; uncoated for aluminum.
Which grade holds up best in high-Vc continuous roughing?
For continuous (no interruptions) roughing at Vc 240-300 m/min, Mitsubishi US7020 and Sandvik GC4325 lead with the highest hot-hardness retention (CVD Al2O3 layer stable to 1100 °C). For interrupted cuts at the same Vc, switch to tougher edge-prep versions (Sandvik GC4345, Iscar IC8350) or larger chipbreaker (CNMG 120412-MR instead of PM). See the carbide inserts by operation hub for high-Vc interrupted-cut solutions.
10. What's Next?
Need help choosing between 8 brands?
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