Tungaloy SN 90° Square Negative Inserts — SNMG, SNMM Heavy-Duty Steel Roughing & Finishing

23 in-stock 90° square Tungaloy indexable carbide turning inserts covering 2 geometry families (SNMG / SNMM) and 4 grade families (T9115 / T9125 / T9225 / NS9530). IC sizes 12.0-25.0 mm. The workhorse 90° negative square for steel and stainless heavy roughing on CNC lathes. 2-3 day dispatch from Zhejiang warehouse, DHL/UPS worldwide 3-7 days, all ISO 1832 compliant.

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

The ISO 1832 SN-shape family delivers a 90° square cutting edge with negative 0° clearance — the strongest edge in the 90° square family. Tungaloy's SN-negative lineup in this collection includes:

• SNMG (M chip-breaker, M tolerance) — 19 SKUs. The workhorse 90° negative square with chip-breaker on both faces. IC sizes 12.0 / 12.7 mm (most common), with TM (medium), TS (sharp), S (sharp), and 37 chip-breaker variants.
• SNMM (M chip-breaker, M tolerance, heavy) — 4 SKUs. The heavy-duty 90° negative square. IC sizes 19.0 / 25.0 mm, with TU / TUS (heavy roughing) chip-breaker variants for steel heavy roughing on large shafts.

SN inserts are the workhorse 90° negative square turning insert for steel and stainless heavy roughing. 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 and 25 mm IC inserts. Tungaloy's SN catalog in this collection features 4 grade families: T9115 (CVD P-grade for general steel), T9125 (CVD M-grade for stainless), T9225 (heavy-duty CVD for steel roughing), and NS9530 (cermet for mirror finishing).

Common applications include heavy roughing of forged steel shafts, gear blanks, and large flanges (using SNMM 19/25 with T9225); general steel profiling (SNMG 12 with T9115/T9125); and mirror surface finishing on steel (SNMG 12 with NS9530 cermet).

Browse by Application & Grade

All 23 SN 90° negative square SKUs are grouped below by application and grade. Click any category to filter the full catalog.

By Workpiece Material

• Carbon Steel / Alloy Steel — SNMG-TM / -S T9115 (CVD P-grade, 5+ SKUs)
• Stainless Steel — SNMG-TM / -S T9125 (CVD M-grade, 8+ SKUs)
• Mirror Finish on Steel — SNMG-TS / -S NS9530 cermet (5+ SKUs)
• Heavy-Duty Steel Roughing — SNMM 19 / 25 with T9225 (3 SKUs)
• Heavy Stainless Roughing — SNMM 25 with T9125 (1 SKU)

By IC Size

• 12.0 mm (SNMG 12): Medium IC, general profiling. 1 SKU (SNMG120412 T9125).
• 12.7 mm (SNMG 1204 / 1208 / 1212): Most common IC, general turning. 18 SKUs across grades.
• 19.0 mm (SNMM 19): Heavy roughing. 1 SKU (SNMM190624-TU T9225).
• 25.0 mm (SNMM 25): Largest, heaviest roughing. 2 SKUs (SNMM250724-TU / 250924-TUS T9125).

By Carbide Grade (4 Tungaloy families)

• T9115 (CVD Steel P-grade) — Tungaloy's standard CVD grade for steel finishing (P10-P20). 5+ SKUs.
• T9125 (CVD Stainless M-grade) — Tungaloy's CVD grade for stainless with interrupted cuts (M15-M30). 8+ SKUs.
• T9225 (Heavy-Duty CVD Steel) — Tungaloy's premium CVD grade for heavy steel roughing (P25-P35). 1 SKU (SNMM 19).
• NS9530 (Cermet) — Tungaloy's premium cermet grade for mirror surface finishing (P05-P15). 5+ SKUs.

By Chip-Breaker (5 Variants)

• TM (Medium): 8+ SKUs. Tungaloy's standard medium chip-breaker for general profiling and roughing.
• TS (Sharp): 3+ SKUs. Tungaloy's sharp chip-breaker for finishing at low feed rates.
• S (Sharp): 5+ SKUs. Tungaloy's premium sharp chip-breaker for finest surface finish.
• 37 (Sharp Cermet): 1 SKU. Tungaloy's cermet mirror finish chip-breaker.
• TU / TUS (Heavy): 4 SKUs. Tungaloy's heavy roughing chip-breaker for SNMM 19 / 25 large IC.

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

Step 1 — Identify the Workpiece

• Carbon steel / alloy steel: SNMG-TM with T9115 (CVD P-grade).
• Stainless steel 304/316: SNMG-TM or SNMG-S with T9125 (CVD M-grade).
• Mirror finish on steel: SNMG-TS / -S / -37 with NS9530 cermet (P05-P15).
• Heavy steel roughing (forged steel, large shafts): SNMM 19 / 25 with T9225 (CVD P25-P35).

Step 2 — Pick the Chip-Breaker

• TM (Medium): Standard chip-breaker for general profiling and roughing.
• TS (Sharp): Sharper chip-breaker for finishing at low feed rates.
• S (Sharp): Premium sharp chip-breaker for finest surface finish.
• 37 (Sharp Cermet): Tungaloy's cermet mirror finish chip-breaker.
• TU / TUS (Heavy): Heavy roughing chip-breaker for SNMM 19 / 25 large IC.

Step 3 — Verify Holder Compatibility

• SN (90° negative): Use Tungaloy DSBN-type negative turning holder with 75° lead angle, or PSBN-type negative holder.
• Verify lead angle: 75° matches SN perfectly. Common holders: DSBNR/L 2020-K12 (12 mm IC), DSBNR/L 3232-P19 (19 mm IC).
• Match IC to holder pocket: SNMG 12 needs 12 mm pocket; SNMM 19 needs 19 mm; SNMM 25 needs 25 mm.

Frequently Asked Questions

Related Tungaloy & Other Brand Inserts

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

23 in-stock SKUs covering SNMG / SNMM in 4 grade families. For specialty SPGR (11° positive), 19+ mm IC for SNMG, or specific Tungaloy equivalent cross-references (Sandvik / Mitsubishi / Kennametal / Iscar / Walter), request a quote — 24-hour response, 2-3 day dispatch from Zhejiang, DHL/UPS worldwide 3-7 days.