Mitsubishi CN 80° Diamond Negative Inserts — CNMG, CNMA, CNMM Heavy-Duty Cast Iron & Steel Turning

66 in-stock 80° negative diamond Mitsubishi indexable carbide turning inserts covering 3 geometry families (CNMG / CNMA / CNMM) and 6 grade families (UC5115 / UC5105 / MC5015 / US735 / VP15TF / UE6020 / AP25N). Optimized for cast iron roughing, stainless profiling, steel turning, and heavy-duty interrupted cuts. IC sizes 12-19 mm. 2-3 day dispatch from Zhejiang warehouse, DHL/UPS worldwide 3-7 days, all ISO 1832 compliant.

About CN 80° Negative Diamond Inserts (CN-Style)

The ISO 1832 CN-shape family delivers an 80° negative-rake rhombic cutting edge — the workhorse geometry for medium-to-heavy turning on cast iron and steel. Mitsubishi's CN lineup includes three main geometry variants:

• CNMG (M chip-breaker, M tolerance) — 58 SKUs. The everyday 80° negative with chip-breaker on both faces. Double-edged economy for general roughing and finishing.
• CNMA (no chip-breaker, A tolerance) — 5 SKUs. Flat-top negative insert with hole only. Used for heavy roughing of cast iron where chip-breaking is not needed, and as a brazed tool blank.
• CNMM (M chip-breaker, M tolerance) — 1 SKU. Heavy-duty negative with stronger edge for interrupted cuts on steel.

CN inserts are the go-to negative turning geometry for cast iron (engine blocks, brake discs, pump housings) and steel (shafts, flanges, gears) where strong edge and good chip control are both required. The 80° included angle provides the best balance between cutting edge strength and chip flow. Compared to 55° DN or 90° SN negative inserts, CNMG sits in the middle — strong enough for roughing, sharp enough for finishing.

Browse by Application & Grade

All 66 CN 80° negative SKUs are grouped below by application and grade. Click any category to filter the full catalog.

By Workpiece Material

• Cast Iron (K-grade) — CNMA-UC5115, CNMA-MC5015, CNMA-UC5105 (10 SKUs)
• Stainless Steel (M-grade) — CNMG-MS US735 (10+ SKUs)
• Carbon Steel / Alloy Steel (P-grade) — CNMG-MS UE6020, CNMG-MS VP15TF (15+ SKUs)
• Mirror Finishing / Precision — CNMG-FH AP25N (cermet)
• Heavy-Duty Steel Roughing — CNMM-HX UE6020 (interrupted cuts)

By Operation

• Cast Iron Heavy Roughing — CNMA-UC5115 / MC5015 (no chip-breaker, free cutting)
• Steel / Stainless Profiling — CNMG-MS US735 / VP15TF
• Mirror Finishing — CNMG-FH AP25N (cermet)
• Interrupted Cut Steel — CNMM-HX UE6020 (heavy)
• General Negative Turning — CNMG series (workhorse)

By Carbide Grade

• CVD Cast Iron (K-grade) — UC5115 (K05-K20), MC5015 (K05-K15 high-speed), UC5105 (K05-K10)
• CVD Stainless Steel (M-grade) — US735 (M10-M25)
• PVD Universal (Miracle Coat) — VP15TF (P10-P25, M10-M25, S10-S20)
• CVD Steel (P-grade) — UE6020 (P20-P30)
• Cermet (Finishing) — AP25N (P05-P15, mirror surface)

How to Choose the Right CN 80° Negative Insert — 3-Step

Step 1 — Identify the Workpiece

• Cast iron (gray, ductile, CGI): CNMA flat-top with UC5115 / MC5015 / UC5105 grade. No chip-breaker is fine for free-cutting cast iron.
• Stainless steel 304/316: CNMG-MS with US735 grade (M-grade CVD coated for stainless).
• Carbon steel / alloy steel: CNMG-MS with UE6020 (P-grade CVD) or VP15TF (PVD universal).
• Mirror finishing on steel: CNMG-FH with AP25N cermet.
• Heavy interrupted cuts on steel: CNMM-HX with UE6020.

Step 2 — Pick the Chip-Breaker

• MS (medium semi-finishing): Light to medium chip-breaker for general profiling and finishing. Most common.
• FH (finishing): Very light chip-breaker for mirror surface and low feed finishing.
• No chip-breaker (CNMA): Flat top, used for cast iron and heavy roughing where chip flow is not constrained.
• HX (heavy): Strong chip-breaker for interrupted cuts and heavy depths.

Step 3 — Verify Holder Compatibility

• CN (80° negative): Use DCLN-type holders (double clamp, 80° lead angle) or PCLN (pin lock). Most common negative turning holders.
• Verify lead angle: 80° matches CNMG perfectly. Some holders (e.g., DCLN 2525-M12) accept 12 mm IC; larger (e.g., DCLN 3232-P19) accept 19 mm IC.
• Match IC to holder pocket: CNMG 12 needs 12 mm pocket; CNMM 19 needs 19 mm pocket.

Frequently Asked Questions

Related Mitsubishi Inserts & Holders

Need a Specific CN 80° Negative Insert Not in Stock?

66 in-stock SKUs covering CNMG / CNMA / CNMM in 7 grades. For specialty CNGG (cermet sharp), CNMA-MM chip-breaker, or specific Mitsubishi equivalent cross-references (Sandvik / Kennametal / Iscar / Walter), request a quote — 24-hour response, 2-3 day dispatch from Zhejiang, DHL/UPS worldwide 3-7 days.