Mitsubishi SN 90° Square Negative Inserts — SNMG, SNMA Heavy-Duty Cast Iron & Steel Turning

31 in-stock 90° square negative Mitsubishi indexable carbide turning inserts covering 2 geometry families (SNMG / SNMA) and 6 grade families (UC5115 / MC5015 / UC5105 / US735 / VP15TF / UE6020 / NX2525). IC sizes 9-19 mm. The strongest negative turning geometry for heavy roughing of cast iron and steel. 2-3 day dispatch from Zhejiang warehouse, DHL/UPS worldwide 3-7 days, all ISO 1832 compliant.

About SN 90° Square Negative Inserts (SN-Style)

The ISO 1832 SN-shape family delivers a 90° square negative-rake cutting edge — the strongest negative turning geometry in the standard ISO lineup. Mitsubishi's SN lineup includes two main geometry variants:

• SNMG (M chip-breaker, M tolerance) — 28 SKUs. The workhorse 90° square negative with chip-breaker on both faces. Double-edged economy for heavy roughing and general turning.
• SNMA (no chip-breaker, A tolerance) — 2 SKUs. Flat-top negative insert with hole only. Used for cast iron heavy roughing where chip-breaking is not needed.

SN inserts are the go-to negative turning geometry for the heaviest roughing on cast iron (engine blocks, brake discs, flywheels) and steel (forged shafts, large flanges). The 90° included angle distributes cutting forces evenly across the strongest edge geometry, allowing depths of cut up to 10 mm with the larger 19 mm IC inserts. Compared to other negative shapes: SN is the strongest, CN (80°) is balanced, DN (55°) is the sharpest.

Mitsubishi's SN catalog emphasizes cast iron coverage — UC5115 / MC5015 / UC5105 grades (CVD K-grade) are heavily represented. Steel and stainless steel are also well-covered with UE6020/UE6110 (P-grade) and US735 (M-grade). The 12.7 mm IC (1204 / 1208 / 1212) is the most common (20+ SKUs), with 9.5 mm and 19.0 mm IC for special sizes.

Browse by Application & Grade

All 31 SN 90° square negative SKUs are grouped below by application and grade. Click any category to filter the full catalog.

By Workpiece Material

• Cast Iron (K-grade) — SNMG UC5115, SNMA MC5015 / UC5105 (12+ SKUs)
• Stainless Steel (M-grade) — SNMG-MS / MA US735 (4+ SKUs)
• Carbon Steel / Alloy Steel (P-grade) — SNMG-MA UE6020 / UE6110 (8+ SKUs)
• Universal (steel + stainless) — SNMG-MA VP15TF (4+ SKUs)
• Mirror Finishing — SNMG NX2525 (cermet)

By Operation

• Cast Iron Heavy Roughing — SNMA MC5015 / UC5105 (free cutting, no chip-breaker)
• Steel / Stainless Heavy Roughing — SNMG190616 UE6020 (19 mm IC, 1.6 mm nose)
• Steel General Turning — SNMG120408-MA UE6020 / UE6110
• Stainless Profiling — SNMG-MA US735 (negative + M-grade)
• Mirror Finishing — SNMG NX2525 cermet

By Carbide Grade

• CVD Cast Iron (K-grade) — UC5115 (K05-K20), MC5015 / MC6035 (K05-K15 high-speed), UC5105 (K05-K10)
• CVD Stainless Steel (M-grade) — US735 (M10-M25)
• PVD Universal (Miracle Coat) — VP15TF (Al-rich, P/M/S grades)
• CVD Steel (P-grade) — UE6020 (P20-P30), UE6110 (P15-P25 high-speed)
• Cermet (Finishing) — NX2525 (P05-P15, mirror surface)

By IC Size

• 9.5 mm (SNMG 09): Small IC, finishing. 2 SKUs (UE6110 steel, NX2525 cermet).
• 12.7 mm (SNMG 12): Most common, general turning. 26 SKUs (the workhorse size).
• 19.0 mm (SNMG 19): Heavy roughing. 2 SKUs (UE6020 steel, UC5115 cast iron).

How to Choose the Right SN 90° Square Negative Insert — 3-Step

Step 1 — Identify the Workpiece

• Cast iron (gray, ductile, CGI): SNMA flat-top with UC5115 / MC5015 / UC5105 grade (K-grade CVD). SNMG with UC5115 for chip-controlled roughing.
• Stainless steel 304/316: SNMG-MS or SNMG-MA with US735 grade (M-grade CVD coated for stainless).
• Carbon steel / alloy steel: SNMG-MA with UE6020 (P20-P30) or UE6110 (P15-P25 high-speed).
• Mirror finishing on steel: SNMG with NX2525 cermet.
• Universal (steel + stainless): SNMG-MA with VP15TF PVD Miracle Coat.

Step 2 — Pick the IC Size

• 9.5 mm IC (SNMG 09): Small diameters, finishing. Use for shafts under 30 mm.
• 12.7 mm IC (SNMG 12): General turning, the most common. Use for shafts 30-100 mm.
• 19.0 mm IC (SNMG 19): Heavy roughing, large diameters. Use for shafts over 100 mm, depths of cut up to 10 mm.

Step 3 — Verify Holder Compatibility

• SN (90° negative): Use DSBN-type holders (double clamp, 75° lead angle) or PSBN (pin lock).
• Verify IC to holder pocket: SNMG 12 needs 12 mm pocket; SNMG 19 needs 19 mm pocket.
• Match lead angle: 75° lead angle is standard for SN, but some holders (e.g., DSKN) use 90° lead. Check the holder spec.

Frequently Asked Questions

Related Mitsubishi Inserts & Holders

Need a Specific SN 90° Square Insert Not in Stock?

31 in-stock SKUs covering SNMG / SNMA in 7 grades. For specialty SNGG (cermet sharp), SNMX, 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.