Mitsubishi DN 55° Diamond Negative Inserts — DNMG, DNMA Heavy-Duty Stainless & Steel Turning

36 in-stock 55° negative diamond Mitsubishi indexable carbide turning inserts covering 2 geometry families (DNMG / DNMA) and 6 grade families (UC5115 / MC5015 / US735 / VP15TF / UE6020 / NX2525). Optimized for stainless steel profiling, cast iron turning, and steel heavy roughing. IC sizes 11-15 mm. 2-3 day dispatch from Zhejiang warehouse, DHL/UPS worldwide 3-7 days, all ISO 1832 compliant.

About DN 55° Negative Diamond Inserts (DN-Style)

The ISO 1832 DN-shape family delivers a 55° negative-rake rhombic cutting edge — the sharpest negative turning geometry for profiling and copy turning. Mitsubishi's DN lineup includes two main geometry variants:

• DNMG (M chip-breaker, M tolerance) — 35 SKUs. The workhorse 55° negative with chip-breaker on both faces. Double-edged economy for general roughing, semi-finishing, and finishing.
• DNMA (no chip-breaker, A tolerance) — 1 SKU. Flat-top negative insert with hole only. Used for cast iron heavy roughing where chip-breaking is not needed.

DN inserts are the go-to negative turning geometry for stainless steel profiling where the 55° angle provides a sharper edge than 80° CN, while the negative rake provides more edge strength than 55° DC positive. This makes DNMG the workhorse choice for stainless shaft turning, sanitary fittings (valves, pumps), and food-grade stainless components. Compared to other negative shapes: SN (90° square) is stronger but duller; CN (80° diamond) is balanced; DN (55° diamond) is the sharpest.

Mitsubishi's DN catalog is rich in chip-breaker variants — MA (medium for general use), MS (medium semi-finishing), GK (heavy roughing), MP (medium profiling), GH (general heavy) — combined with 7 grade options. The 15.0 mm IC is most popular (25+ SKUs), followed by 11.0 mm IC (5+ SKUs).

Browse by Application & Grade

All 36 DN 55° negative SKUs are grouped below by application and grade. Click any category to filter the full catalog.

By Workpiece Material

• Stainless Steel 304/316 (M-grade) — DNMG-MS US735, DNMG-MA US735
• Carbon Steel / Alloy Steel (P-grade) — DNMG-MA UE6020 / UE6110
• Cast Iron (K-grade) — DNMA UC5115, DNMG-GK MC5015, DNMG UC5115
• Mirror Finishing / Precision — DNMG NX2525 (cermet)
• Universal (steel + stainless) — DNMG-MA VP15TF PVD

By Operation

• Stainless Steel Profiling — DNMG-MS US735 (interrupted cuts)
• Cast Iron High-Speed — DNMG-GK MC5015 / DNMA UC5115
• Steel Heavy Roughing — DNMG-MA UE6020 / UE6110 (P20-P30)
• Mirror Finishing — DNMG NX2525 cermet
• Universal Finishing — DNMG-MA / MS VP15TF (PVD all-rounder)

By Carbide Grade

• CVD Cast Iron (K-grade) — UC5115 (K05-K20), MC5015 (K05-K15 high-speed)
• CVD Stainless Steel (M-grade) — US735 (M10-M25)
• PVD Universal (Miracle Coat) — VP15TF (Al-rich, P10-P25, M10-M25, S10-S20)
• CVD Steel (P-grade) — UE6020 / UE6110 (P15-P30)
• Cermet (Finishing) — NX2525 (P05-P15, mirror surface)

By Chip-Breaker

• MA (Medium All-round) — General purpose. The most common, 15+ SKUs across all grades.
• MS (Medium Semi-finishing) — Lighter chip-breaker, for finishing and stainless profiling.
• GK (General Heavy) — Stronger chip-breaker, for roughing of cast iron and steel.
• MP (Medium Profiling) — Optimized for profiling operations.
• GH (General Heavy) — Stronger chip-breaker for steel roughing.

How to Choose the Right DN 55° Negative Insert — 3-Step

Step 1 — Identify the Workpiece

• Stainless steel 304/316 (most common): DNMG-MS or DNMG-MA with US735 grade (M-grade CVD coated for stainless).
• Carbon steel / alloy steel: DNMG-MA with UE6020 or UE6110 (P-grade CVD steel).
• Cast iron (gray, ductile): DNMA flat-top with UC5115, or DNMG-GK with MC5015 for high-speed.
• Mirror finishing on steel: DNMG with NX2525 cermet.
• Universal (steel + stainless): DNMG-MA with VP15TF PVD Miracle Coat.

Step 2 — Pick the Chip-Breaker

• MA (Medium All-round): For general profiling and semi-finishing. Most common.
• MS (Medium Semi-finishing): Lighter chip-breaker for finishing and stainless profiling with low feed.
• GK (General Heavy): Stronger chip-breaker for cast iron high-speed and steel roughing.
• MP / GH: Specialty chip-breakers for profiling and heavy roughing respectively.

Step 3 — Verify Holder Compatibility

• DN (55° negative): Use DDJN-type holders (double clamp, 55° lead angle) or PDJN (pin lock).
• Verify lead angle: 55° matches DNMG perfectly. Common holders: DDJNR/L 2020-K11 (11 mm IC), DDJNR/L 2525-M15 (15 mm IC).
• Match IC to holder pocket: DNMG 11 needs 11 mm pocket; DNMG 15 needs 15 mm pocket.

Frequently Asked Questions

Related Mitsubishi Inserts & Holders

Need a Specific DN 55° Negative Insert Not in Stock?

36 in-stock SKUs covering DNMG / DNMA in 7 grades and 5 chip-breaker variants. For specialty DNGG (cermet sharp), DNMX, 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.