SUMITOMO TCMT16T304N-SU AC820P CVD Carbide Insert | TCMT32.51N-SU
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1. Product Overview
Which positive turning insert is best suited for high-speed fine-to-medium steel turning and internal boring operations where low cutting resistance and superior tool life are required?
The SUMITOMO TCMT16T304N-SU AC820P (ANSI designation: TCMT32.51N-SU AC820P) is a high-productivity 60° triangular single-sided indexable turning insert engineered with a 7° positive clearance angle to minimize cutting force and chatter. Powered by SUMITOMO's flagship AC820P Absotech Platinum CVD Coating Grade—featuring an ultra-smooth, dense TiCN and nano-textured Al2O3 multi-layer coating over a specialized tough carbide core—this insert delivers industry-leading crater wear and flank wear resistance at elevated cutting speeds across ISO P05–P25 steel ranges.
Featuring a precise 0.4 mm (1/64") corner radius, Neutral (N) edge prep, and the versatile SU Medium-Cut Chipbreaker, this insert achieves excellent dimensional control, smooth chip evacuation, and low vibration on both external turn-facing shanks and internal boring bars during high-efficiency CNC production cycles.
ISO / ANSI Designation Breakdown
2. Key Features
- Absotech Platinum AC820P CVD Coating: Smooth coating surface reduces friction and heat build-up, extending tool life by up to 2x during continuous high-speed steel machining.
- 7° Positive Relief Edge Geometry: Cuts radial resistance substantially, enabling stable performance on small-diameter boring bars and thin-wall workpieces.
- SU Medium-Cut Chipbreaker: Form-engineered rake face produces tight, manageable C-shaped chips over varied depths of cut.
- 0.4 mm Precision Radius: Ideal for fine-to-medium profiling, shoulder turning, and obtaining low Ra surface roughness values.
- High Thermal Shock Resistance: Formulated to withstand elevated cutting temperatures without premature plastic deformation or flank breakdown.
3. Specifications & Dual-Unit Comparison
| Specification Parameter | Metric Unit (ISO Standard) | Imperial Unit (ANSI Standard) |
|---|---|---|
| Insert Designation | TCMT16T304N-SU | TCMT32.51N-SU |
| Inscribed Circle (IC) | 9.525 mm | 0.375" (3/8") |
| Thickness (S) | 3.97 mm | 0.156" (5/32") |
| Corner Radius (RE) | 0.4 mm | 0.0156" (1/64") |
| Hole Diameter (D1) | 4.40 mm | 0.173" |
| Substrate Grade | Absotech Platinum CVD (AC820P) | Absotech Platinum CVD (AC820P) |
Recommended Cutting Parameters
| Workpiece Material | Cutting Speed (Vc) | Feed Rate (f) | Depth of Cut (ap) |
|---|---|---|---|
| Carbon Steel (1045, 1018, A36) | 180 - 350 m/min (590 - 1150 SFM) |
0.08 - 0.25 mm/rev (0.003 - 0.010 ipr) |
0.5 - 2.5 mm (0.020 - 0.098 in) |
| Alloy Steel (4140, 4340, 8620) | 150 - 300 m/min (490 - 980 SFM) |
0.08 - 0.22 mm/rev (0.003 - 0.009 ipr) |
0.5 - 2.2 mm (0.020 - 0.086 in) |
| Die Steel / Tool Steel (P20, H13 Annealed) | 120 - 240 m/min (390 - 780 SFM) |
0.06 - 0.18 mm/rev (0.002 - 0.007 ipr) |
0.4 - 1.8 mm (0.015 - 0.070 in) |
Recommended Compatible Toolholders (ISO Screw Clamp Turning & Boring Holders):
Compatible with standard external toolholders: STGCR/L 2020K16, STFCR/L 2020K16, Internal Boring Bars: A16M-STFCR16, S20R-STFCR16
Workpiece Material Matrix (ISO 513 Standard)
| ISO Material Group | Suitability | Common Grade Examples | Performance Rating |
|---|---|---|---|
| P (Steel) | Primary Choice | 1045 Carbon Steel, 4140 Alloy Steel, 8620 Steel | ★★★★★ (Optimal) |
| K (Cast Iron) | Secondary Choice | Ductile Iron, Nodular Cast Iron (Light finishing) | ★★★☆☆ (Good) |
| M (Stainless Steel) | Conditional | 410, 420 Ferritic/Martensitic Stainless Steels | ★★☆☆☆ (Limited) |
| S (Exotic Alloys) | Not Recommended | Inconel, Titanium Alloys | ★☆☆☆☆ (Not Recommended) |
4. Applications
- High-Speed Steel Shaft Profile Turning: High-efficiency outer diameter turning and shoulder contouring on alloy steel shafts.
- Small-Diameter Internal Hole Boring: Precision ID boring using positive screw-clamp bars where chatter suppression is essential.
- Automotive Gear & Hub Pre-Finishing: Fast metal removal on forged carbon steel blanks prior to grinding or hard turning operations.
5. Compatibility
Fits all standard ISO positive screw-clamp external shanks (STGCR/L, STFCR/L) and internal boring bars (A/S-STFCR/L). Compatible with standard CNC turning machines and automatic lathes from Haas, Mazak, Okuma, Doosan/DN Solutions, Citizen, and Hardinge.
6. Grade Comparison & Equivalent Models
| Manufacturer | Equivalent Grade | Equivalent ISO Insert Designation |
|---|---|---|
| SUMITOMO (Original) | AC820P (Absotech) / AC8025P | TCMT16T304N-SU |
| Sandvik Coromant | GC4325 / GC4425 | TCMT16T304-PM / TCMT32.51-PM |
| Kyocera | CA5525 / CA315 | TCMT16T304HQ / TCMT32.51HQ |
| Tungaloy | T9215 / T9125 | TCMT16T304-PSS |
| Iscar | IC807 / IC8150 | TCMT 16T304-SM |
7. Why Choose Us
We provide 100% genuine SUMITOMO Electric Hardmetal indexable cutting tools directly through authorized distribution channels. Every box undergoes batch verification to guarantee edge uniformity, coating adhesion, and dimensional stability for automated high-speed turning.
Verified Customer Reviews
AC820P is unbelievable on 4140 pre-hardened steel. We ran these TCMT 16T304 inserts at 900 SFM on our Haas ST-20, and tool life increased by 40% compared to our previous grade.
Hervorragende Wendeschneidplatte für die Stahlbearbeitung. Die Standzeit bei der Innenbearbeitung auf A16M Bohrstangen ist extrem stabil.
Inserti di eccezionale qualità. Il grado AC820P garantisce un’ottima resistenza all'usura del petto anche ad altissima velocità di taglio.
S45CとSCM440の旋削でAC820Pを使っています。高速切削でも摩耗が遅く、安定して量産ラインを回せます。
The 0.4mm corner radius works well for light shoulder profiling. Excellent chip breaking with the SU geometry on carbon steel stock.
8. AI-Style FAQ & Troubleshooting
Troubleshooting Quick Reference
| Problem Encountered | Probable Cause | Recommended Solution |
|---|---|---|
| Crater Wear on Rake Face | Cutting speed Vc is excessively high causing high heat density | Reduce cutting speed Vc by 10-15% or ensure coolant flow is directly hitting the chip-tool interface. |
| Chipping on Corner Radius | Heavy interrupted cuts or excessive feed rate f for 0.4mm corner radius | Reduce feed rate f or switch to a 0.8mm radius insert (TCMT16T308) for better edge strength. |
| Bird-nesting / Stringy Chips | Depth of cut ap is below the active SU chipbreaker threshold | Increase depth of cut ap above 0.5 mm to engage the chipbreaker wall cleanly. |
Under ISO 513:2012 classification standards, SUMITOMO AC820P Absotech Platinum CVD coated grade represents the benchmark standard for high-efficiency, continuous-to-light interrupted turning of ISO P10–P25 carbon steels and alloy steels.
Technical FAQ & Buying Guide
Absolutely. Our CNC carbide inserts (including CNMG, WNMG, DNMG, and APMT series) are manufactured strictly adhering to international ISO/ANSI specifications. A CNMG 120408 from OYYU BEYOND will flawlessly fit any standard turning tool holder or indexable tool from major global brands like Sandvik Coromant, Kennametal, Iscar, Walter, or SECO, providing a highly cost-effective premium alternative without sacrificing tolerance or tool life.
We offer optimized CVD and PVD multi-layer coatings for different ISO material groups:
- For Carbon/Alloy Steel (ISO P): Choose our thick multi-layer CVD coated grades (e.g., Al2O3 + TiN). They provide exceptional crater wear resistance and thermal barriers during high-speed dry or wet roughing.
- For Stainless Steel (ISO M): Choose our nano-structured PVD coated grades with sharp, positive chipbreakers (like -TM or -MA). This combination prevents work hardening and effectively controls sticky chips.
The optimal cutting parameters vary depending on the workpiece hardness and operation type:
- For General Steel Turnings: Recommended cutting speed ($V_c$) ranges from 150 to 280 m/min, with a feed rate ($f$) of 0.15 to 0.45 mm/rev.
- For Stainless Steel Finishing: Recommended cutting speed ($V_c$) is 120 to 200 m/min, with a feed rate ($f$) of 0.10 to 0.25 mm/rev.Always adjust parameters based on early wear patterns: increase $V_c$ if built-up edge occurs, or reduce $V_c$ if severe flank wear is observed.
Yes, we support machine shops, distributors, and global buyers with tiered wholesale pricing and competitive volume discounts. We also provide OEM custom manufacturing solutions for tool holders and carbide inserts based on your technical drawings. Contact our team to request a quick B2B quotation.
We provide secure worldwide express shipping (via DHL, FedEx, and UPS) with specialized, vibration-proof industrial packaging to ensure tools arrive in perfect condition. In-stock items are dispatched within 24-48 hours, while custom or bulk orders typically have a stable lead time of 15-25 days.
All our cutting tools and tool holders are manufactured strictly in accordance with ISO 9001 and international industrial standards. Every batch undergoes 100% rigorous quality control testing using high-precision optical measuring equipment to ensure reliable tool life and stable performance in continuous mass production.