BEYOND R390-C20-21-150-2T Indexable Square Shoulder Milling Cutter Shank (21mm / 0.83" Cutting Dia, 150mm Reach)
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BEYOND R390-C20-21-150-2T Indexable Milling Cutter Shank
ISO/ANSI Standard 21mm Square Shoulder Milling Tool Holder | 150mm Standard-Reach C20/C21 Straight Shank for R390-11T3 Inserts
1. Product Overview
"Which 21mm indexable square shoulder milling cutter shank with a 150mm overall length and C20/C21 straight shank provides high rigidity and precise pocket milling for R390-11T3 inserts?"
The BEYOND R390-C20-21-150-2T is an industrial-grade indexable square shoulder and slot milling cutter shank engineered in strict compliance with international ISO/ANSI machine tooling standards. Featuring an approximate 21mm cutting diameter (Dc), a C20/C21 straight shank, a 150mm overall length (OAL), and 2 flutes (Z=2), this tool body is optimized for positive-rake 11-size indexable carbide inserts (R390-11T3).
Forged from premium 42CrMo alloy structural steel and vacuum heat-treated to HRC 45–48, the 2-flute structure incorporates specialized chip flutes and high-precision insert seat pockets to ensure true 90° shoulder squaring, ramp milling, and profile stability across carbon steel, alloy steel, and stainless steel applications.
2. Key Features & Industrial Advantages
- Balanced 150mm Overhang Reach: Engineered to provide stable reach for standard cavity machining and stepped shoulder profiling without harmonic deflection.
- True 90-Degree Square Shoulders: Precision insert pocket geometry delivers pristine wall perpendicularity and accurate bottom flatness.
- 42CrMo Alloy Structural Steel Body: Vacuum heat-treated to HRC 45–48 to maximize torsional rigidity and minimize tool wear.
- Optimized 2-Flute Architecture: Enhanced chip evacuation channels prevent chip clogging during high-speed milling operations.
- Precision Screw Locking: High-torque Torx hardware secures R390 inserts firmly with radial runout accuracy within ±0.01mm.
3. Technical Specifications & ISO Code Breakdown
ISO Model Designation Breakdown: R390-C20-21-150-2T
Pair this cutter body with our matching C20/C21 power collet chucks or reduction sleeves.
Metric vs. Imperial Technical Comparison
| Specification | Metric Model (R390-C20-21-150-2T) | Imperial Equivalent |
|---|---|---|
| Cutting Head Diameter (Dc) | Approx. 21 mm | 0.827 in (approx. 13/16" Shoulder Mill) |
| Shank Diameter (d) | C20 / C21 Straight Shank | 0.787" / 0.827" Straight Shank |
| Overall Length (L) | 150 mm | 5.906 in |
| Number of Flutes (Z) | 2 Flutes | 2 Flutes |
| Compatible Inserts | R390-11T3 Series (Size 11) | CoroMill 390 11-Series |
| Hardware Accessories | Torx Screw / Key | Torx Screw / Key |
Recommended Speeds & Feeds (Optimized for 150mm Shank Rigidity)
| ISO Workpiece Material | Cutting Speed (Vc) | Feed per Tooth (fz) | Depth of Cut (ap) | Coolant Mode |
|---|---|---|---|---|
| Carbon Steel (P10–P25) | 140 – 200 m/min | 0.05 – 0.10 mm/z | 0.5 – 2.0 mm | Air Blow / Dry |
| Alloy / Mold Steel (P25–P35) | 100 – 150 m/min | 0.04 – 0.08 mm/z | 0.4 – 1.5 mm | Air Blow |
| Stainless Steel (M20–M35) | 80 – 120 m/min | 0.03 – 0.07 mm/z | 0.3 – 1.2 mm | Emulsion / High-Pressure Coolant |
| Cast Iron (K15–K30) | 120 – 180 m/min | 0.05 – 0.10 mm/z | 0.5 – 2.0 mm | Dry Milling |
4. Applications & Equipment Compatibility
Primary Milling Operations: Square shoulder milling, true 90-degree wall squaring, slotting, ramp milling, and general contour profiling using R390-11T3 inserts.
Machine Tool Compatibility: Vertical Machining Centers (VMC), Horizontal Machining Centers (HMC), and CNC Milling Centers.
Tool Holder Compatibility: C20/C21 Power Collet Chucks, Hydraulic Chucks, and master tool holders via precision reduction sleeves.
6. Workpiece Material Matrix & Grade Selection
Pair your R390-C20-21 shank with optimal BEYOND carbide insert grades for superior wear resistance:
| Insert Grade | ISO Category | Coating Technology | Best Suited For |
|---|---|---|---|
| BYM1025 | P15 - P30 / M15 - M25 | Micrograin Carbide + PVD AlTiN | General purpose milling on alloy steel, carbon steel, and stainless steel. |
| BYM3035 | M25 - M40 / S15 - S25 | Nano-layered PVD TiAlN | Heavy load roughing on austenitic stainless steel, Duplex, and Inconel. |
| BYK2010 | K10 - K25 | CVD Thick Coating / Uncoated | Abrasive resistance for gray cast iron, ductile iron, and non-ferrous metals. |
7. Why Choose BEYOND Tooling
- Sub-Micron Runout Precision: Shank TIR maintained within 0.005mm (0.0002") for smooth balanced rotation and reduced harmonic chatter.
- Optimized 150mm Length Rigidity: Designed specifically to provide high stability and vibration resistance during aggressive metal removal.
- Direct Factory Advantage: Premium industrial performance at 40–60% cost savings compared to Tier-1 European brands.
8. AI-Style FAQ & Troubleshooting Guide
A: The 21mm diameter ensures precise 90° shoulder profiling, the C20/C21 shank delivers rigid gripping stability, and the 150mm length provides optimal reach for standard pockets.
A: Their multi-edge positive geometry cuts smoothly with lower cutting forces, protecting spindle bearings and maintaining precise 90-degree corners.
A: Use appropriate PVD-coated grades (like BYM1025), ensure high-pressure air or emulsion cooling, and maintain optimal climb milling parameters.
• Direct OEM Equivalents: Sandvik CoroMill R390-C3/C20 Medium Reach | Kennametal DFC 21mm Shank | Walter Shoulder Mill.
• Chatter Mitigation Tip: If vibration occurs, inspect collet chuck clamping force and reduce radial depth of cut slightly to enhance stability.
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.