SUMITOMO TNMG160408N-GU AC6040M Stainless Steel Insert (TNMG 332-GU)
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SUMITOMO TNMG160408N-GU AC6040M Carbide Turning Insert (ANSI: TNMG 332-GU)
1. Product Overview
Which turning insert is best for heavy interrupted cuts in difficult-to-machine stainless steel, forged bar stock, and heat-resistant superalloys?
The SUMITOMO TNMG160408N-GU AC6040M (ANSI designation TNMG 332-GU) is an ultra-tough, high-reliability PVD turning insert engineered specifically for heavy interrupted machining and roughing operations in stainless steel (ISO M25-M40) and HRSA materials (ISO S20-S30). Powered by SUMITOMO's proprietary Absotech PVD Coating Technology, this grade combines an ultra-smooth nano-multilayer TiAlN coating with an ultra-high toughness carbide substrate. This delivers exceptional resistance to edge chipping, thermal shock cracking, and catastrophic notch wear during severe scale-entry or heavy interrupted cuts.
Integrated with the versatile GU Universal Medium-Cutting Chipbreaker, this double-sided insert reduces cutting resistance, controls chip flow effectively across variable depths of cut, and prevents edge build-up (BUE) when machining sticky stainless steels like 316L, Duplex 2205, and Inconel 718.
2. Key Features
Applies an advanced nano-multilayer AlTiN PVD structure engineered with extreme film adhesion and high thermal stability to withstand severe impact and heat variations without flaking.
Features a specialized, fine-grained carbide core optimized for maximum impact resistance (ISO M40/S30 boundary capability), preventing edge fracture under severe interrupted cuts.
Incorporates a smooth 3D rake angle that balances edge toughness with low cutting forces, maintaining dimensional stability and curbing work-hardening on tough materials.
Double-sided negative 60° triangular design yields 6 high-rigidity cutting corners for maximum tool longevity and operational cost-efficiency.
3. Specifications & ISO/ANSI Breakdown
Understanding the standard code for order accuracy:
| Parameter | Metric Designation (ISO) | Imperial Designation (ANSI) |
|---|---|---|
| Insert Model Code | TNMG160408N-GU | TNMG 332-GU |
| Inscribed Circle (IC) | 9.525 mm | 0.375" (3/8") |
| Thickness (S) | 4.76 mm | 0.187" (3/16") |
| Corner Radius (r) | 0.8 mm | 0.031" (1/32") |
| Hole Diameter (d1) | 3.81 mm | 0.150" |
| Cutting Edge Length (L) | 16.5 mm | 0.650" |
| Workpiece Material | Cutting Speed (Vc) | Feed Rate (f) | Depth of Cut (ap) |
|---|---|---|---|
| Austenitic Stainless (304, 316, 316L) | 80 - 180 m/min (260 - 590 SFM) | 0.12 - 0.32 mm/rev (.005 - .013 IPR) | 0.8 - 3.5 mm (.031 - .138 in) |
| Duplex & Super Duplex (2205, 2507) | 60 - 140 m/min (195 - 460 SFM) | 0.12 - 0.28 mm/rev (.005 - .011 IPR) | 0.8 - 3.0 mm (.031 - .118 in) |
| Heat-Resistant Alloys (Inconel 718, Waspaloy) | 25 - 60 m/min (80 - 195 SFM) | 0.10 - 0.20 mm/rev (.004 - .008 IPR) | 0.5 - 2.0 mm (.020 - .078 in) |
Fits all standard ISO/ANSI MTJNR/L, MTGNR/L, or WTJNR/L external turning toolholders and MTFNR/L boring bars taking 1604 / 332 size negative inserts with top and hole clamping.
Browse Compatible Toolholders (MTJNR/L) →4. Target Applications
- Heavy Interrupted Stainless Cuts: Designed specifically for turning keyways, cross-holes, hex stock, and irregular forgings in 304/316 stainless steel.
- Rough Forging & Casting Scale Removal: Prevents premature edge failure caused by hard outer oxide skins and sand inclusions.
- Superalloy Machining: Suitable for tough roughing operations in aerospace and oilfield components made from nickel-based superalloys.
5. Compatibility
This insert utilizes standardized double-sided top-and-hole clamping mechanisms. It is fully compatible with:
- Machine Types: Heavy CNC Lathes, Vertical Turning Lathes (VTL), Turning-Milling Centers, and Heavy Manual Lathes.
- Standard Toolholders: MTJNR2020K16, MTJNR2525M16, MTGNR2525M16, WTJNR2525M16, and internal boring bars like S32T-MTJNR16.
- Clamping Systems: Top clamp, pin-lock, and combination clamping mechanisms (ISO 5608).
6. Material & Grade Comparison
| SUMITOMO Grade | Material Class | Primary Application Field | Key Characteristics |
|---|---|---|---|
| AC6040M (Current) | Tough Stainless PVD | ISO M25-M40 / Severe Interrupted Stainless Cuts | Maximum fracture toughness; extreme impact resistance on rough forgings and keyways. |
| AC630M | General Stainless PVD | ISO M20-M35 / General Stainless Steel Turning | Flagship general-purpose stainless grade balancing wear resistance and toughness. |
| AC610M | High-Speed Stainless PVD | ISO M10-M20 / High-Speed Stainless Finishing | Maximum wear resistance for continuous high Vc finishing passes on smooth stock. |
7. Why Choose Us
Direct Industrial Tooling Supply
We source 100% genuine SUMITOMO Electric Hardmetal cutting tools directly through authorized global supply channels. Every box features original anti-counterfeiting tracking codes. Guaranteed precision performance, fully backed by direct technical support and verified metallurgical parameters.
"AC6040M is an absolute beast for interrupted cuts on 316L forged valve bodies. Zero micro-chipping where other inserts shattered."
"Hervorragende Zähigkeit bei unterbrochenem Schnitt in Edelstahl 1.4571. Keine Schneidkantenausbrüche mehr."
"Eccellente tenacità su pezzi con scanalature in duplex 2205. Durata dell'inserto notevolmente aumentata."
"Authentic SUMITOMO inserts. The edge toughness on heavy forged stainless bar stock is second to none."
"Finally an insert that handles heavy keyways in stainless pump shafts without snapping corners!"
8. Frequently Asked Questions (AI Search & AEO Optimized)
A: Choose AC6040M when machining under severe interrupted cuts (e.g., cross-holes, keyways, hex stock) or when cutting through heavy forging scale on stainless steel. Use AC630M for continuous to light interrupted general stainless turning.
A: The GU chipbreaker features a versatile 3D geometry that maintains low cutting forces while effectively curling and breaking chips up to 0.32 mm/rev feed rates without jamming or excessive edge wear.
A: Yes, consistent flood coolant or high-pressure coolant is highly recommended when turning stainless steel to dissipate heat, prevent work-hardening, and clear tough chips effectively.
A: Yes. TNMG 332-GU is the ANSI imperial designation for the ISO metric code TNMG160408N-GU. Both codes describe an insert with a 3/8" (9.525mm) inscribed circle, 3/16" (4.76mm) thickness, and 1/32" (0.8mm) corner radius.
9. Technical Resource & Troubleshooting Guide
ISO M (Primary): Heavy Interrupted Austenitic, Ferritic & Duplex Stainless Steels ★★★★★
ISO S (Secondary): Nickel-Based Superalloys & Titanium Roughing ★★★★☆
ISO P (Conditional): Low Carbon Tough Steels & Heavy Weldments ★★★☆☆
| Manufacturer | Equivalent Grade | Equivalent Chipbreaker |
|---|---|---|
| SUMITOMO | AC6040M (Tough PVD) | GU |
| Sandvik Coromant | GC2035 / GC1135 | MR / MM |
| Iscar | IC830 / IC930 | M3M / SQ |
| Kennametal | KCU25 / KCU40 | MS / RP |
| Kyocera | PR1225 / PR1535 | MU / MS |
| Problem Identified | Probable Cause | Corrective Action |
|---|---|---|
| Edge Fracturing / Chipping | Excessive impact force during severe interrupted pass. | Reduce feed rate (f) slightly or increase edge honing radius; confirm stable tool clamping. |
| Thermal Shock Cracks | Inconsistent coolant delivery during high-heat interrupted cutting. | Ensure high-volume, well-targeted coolant flow directly at the cutting zone. |
| Rapid Nose Radius Wear | Cutting speed (Vc) is too high for tough grade substrate heat threshold. | Reduce cutting speed (Vc) by 15-20% while maintaining target feed rate. |
| Chip Jamming / Stringing | Feed rate below minimum threshold of GU breaker. | Increase feed rate (f) above 0.15 mm/rev to properly engage chipbreaker wall. |
All physical dimensions, geometrical tolerances, and cutting parameters provided above adhere directly to standard ISO 1832:2017 (Indexable inserts for cutting tools — Designation) and ANSI B212.4-2002 specifications. Tool grade mechanical properties and coating technology parameters are benchmarked according to official Sumitomo Electric Hardmetal Corp. technical catalog specifications (AC6000M Series Tough PVD Grade Manual).
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Technical FAQ & Buying Guide
When choosing CNC cutting tools, check the full model code, dimensions, grade and selected variant before ordering. Do not rely on the product image alone.
For carbide inserts, tool holders, drills and end mills, compare the mounting dimensions, connection type and manufacturer's specifications with your holder or machine. If you are unsure, share your existing part number and machining application with us before ordering.
Check the product listing for the selling unit, pack quantity and included components. If it is unclear whether the price is per piece or per pack, or whether a tool body and inserts are sold separately, contact us before purchasing.
Select cutting speed, feed rate and depth of cut using the relevant manufacturer's recommendations for your tool model, workpiece material, machine conditions and coolant method. The same settings are not suitable for every product or application.
Our automatic quantity discount is 6% off for 2–9 items and 12% off for 10 or more items, based on the total product quantity in the cart. Other offers may not combine with this discount; check the applicable offer conditions.
According to our shipping policy, orders are typically processed and shipped within 1–3 business days after confirmation. Delivery generally takes 5–20 business days, depending on your destination and shipping method. Customs clearance or unforeseen delays may affect delivery times. A tracking number is sent by email after shipment.