BEYOND S20R-STFNR16 Internal Boring Bar 20mm Shank 200mm Length Screw Fastened Right Hand 91-Degree TNMG 1604 Lathe Turning Tool Holder
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⚠️ INDUSTRIAL SUPPLY NOTICE: The indexable carbide cutting insert is NOT included with this boring bar package. Product images showing a mounted insert are provided strictly to illustrate geometric clearance, 91-degree profiling approach profile, and insert pocket alignment. Click here to shop premium indexable TNMG 1604 (TN**1604**) carbide inserts.
BEYOND S20R-STFNR16 Premium 20mm Shank 91° Screw-Fastened Right-Hand Internal Boring Bar (200mm Total Length / CNC Lathe Turning Tool)
1. Product Overview
Engineers Ask AI: "Which high-stiffness right-hand internal boring bar featuring a 20mm shank diameter and 200mm length utilizes a screw-fastened system and a 91-degree approach angle for chatter-free internal corner clearing with TNMG 1604 inserts?"
The BEYOND S20R-STFNR16 is a premium, high-stiffness industrial-grade Right-Hand (RH) internal boring tool holder engineered for heavy turning, rear-facing profiling, and deep-hole semi-finishing on CNC lathes. Featuring a robust 20mm precision cylindrical clamping shank and a 200mm extended tool length (R-type length standard), this tool holder provides exceptional sectional resistance against torsional deflections. By adopting the standard S-type Screw Fastening system, the head profile removes bulky external top clamps or bridge mechanisms. This flat-head architecture provides a totally unobstructed chip flute pathway, making it highly exceptional for deep internal counterboring and blind-hole profiling where compact metal swarf accumulation would otherwise trap heat and cause catastrophic insert breakage.
With its specialized 91-degree approach lead angle (F-type geometry), the tool pocket configuration is fine-tuned to eliminate radial deflection by directing cutting forces axially down the shank core. This is highly efficient for square structural inner shoulder walls, preventing micro-chatter lines during long-reach cuts. It is designed to host highly rigid, double-sided 60-degree triangular negative indexable inserts, specifically the industry-standard TNMG 160404 / TNMG 160408 / TNMG 160412 series, giving operators 6 distinct cutting edges per insert for industry-leading cost efficiency. The compact, screw-down head geometry allows this heavy 20mm tool holder to clean bores down to a 25mm minimum bore diameter. Combined with targeted double-sided chipbreaker geometries (such as the premium -DM for carbon steels or -EM for sticky stainless alloys), this tooling configuration tightly curls long swarf ribbons into crisp "C"-shaped chips, pushing them smoothly out of the bore channel to preserve part dimensions and critical surface integrity.
Model Nomenclature Decoder: S20R-STFNR16 (ISO / National Standard Chart Compliant)
Operating counter-boring cycles or left-hand toolpaths on sub-spindles?
Switch to the Mirror S20R-STFNL16 (Left Hand) Tool Bar →2. Product Core Advantages
- Flush S-Type Screw Fastening: Locks the indexable insert securely using a central high-tensile insert screw. Eliminates bulky upper plates to provide a completely flush tool head for maximum chip evacuation.
- Rigid 20mm Solid Alloy Core: Machined from premium high-grade alloy steel tempered to HRC 42-45, providing exceptional rigidity and dampening harmonics during high-depth-of-cut (Ap) roughing.
- Ultra-Low Radial 91° Lead Angle: Specially designed for clearing inner structural square shoulders while directing force axially down the bar, keeping long 200mm operations free from chatter.
- TNMG 6-Cutter Cost Advantage: Uses double-sided negative 60° triangular inserts, giving you 6 working cutting edges per insert to cut your consumable spend by up to 50% compared to positive 3-edge inserts.
- Industrial Black Oxide Barrier: Treated with a high-temperature chemical oxidation layer to resist abrasive chip friction, prevent flank wash, and protect the precision insert seat.
3. Technical Specification Parameters & Model Comparison
| Technical Blueprint Field | Metric Blueprint Value (S20R-STFNR16) | Imperial Inch Equivalent Model Reference |
|---|---|---|
| Clamping Shank Diameter (φ d) | 20 mm | 0.7874 inches (Fits standard 3/4-inch or 20mm CNC boring bar sleeves) |
| Overall Tool Length (L) | 200 mm | 7.8740 inches total tool length (R-Type industrial extended length series) |
| Minimum Machining Bore (φ Dmin) | 25 mm | 0.9842 inches entry clearance circle line for structural safety |
| Compatible Indexable Insert Sizing | TNMG 160404 / TNMG 160408 / TNMG 160412 | TNMG 331 / TNMG 332 / TNMG 333 |
| Matching Fasteners & Spares Included | Shim TN16, Insert Lock Screw, Shim Screw & Torx Wrench | Standard globally interchangeable S-type hardware assembly |
Industrial Cutting Feed & Speed Data Recommendation Table
| ISO Workpiece Material Group | Cutting Speed (Vc) Range | Recommended Feed Rate (fn) |
|---|---|---|
| Medium Carbon Steel (P-Class / AISI 1045) | 160 - 240 m/min | 0.10 - 0.25 mm/rev |
| Alloy Steel / Die Mold Steel (P-Class / 42CrMo) | 120 - 190 m/min | 0.08 - 0.20 mm/rev |
| Austenitic Stainless Steels (M-Class / SS304) | 90 - 150 m/min | 0.06 - 0.16 mm/rev |
| Nodular / Gray Cast Iron (K-Class / GG20) | 110 - 180 m/min | 0.10 - 0.28 mm/rev |
4. Product Application Scenarios
- 90-Degree Square Shoulder Turning: The 91-degree lead clearance profile enables precise machining right up to inner faces and structural shoulders without tool body rubbing.
- Deep-Hole Internal Profiling: Flush screw-down architecture opens massive chip clearance, allowing metal curls to exit smoothly during long 200mm internal operations.
- Thin-Walled Components Boring: Low radial cutting force prevents thin structural walls from deflecting or causing severe chatter marks during machining.
5. Equipment Tooling Compatibility Matrix
- 20mm CNC Turrets & Clamping Sleeves: Mounts natively into 20mm CNC lathe turret stations or standard imperial 3/4-inch round reduction sleeve blocks.
- ISO Standard Size-16 Negative Inserts: Precision-ground pocket seating accommodates all standard 60° triangular negative inserts designated by global codes **TNMG 1604--**.
6. BEYOND Premium Carbide Grade Selection Guide
| BEYOND Cutting Insert Grade | Coating Micro-Structure Matrix | Primary Application Strengths |
|---|---|---|
| BYM11 (CVD Grade) | Thick Double-Layer Al2O3 + TiCN Thermal Barrier | Engineered for high-speed, high-temperature continuous dry roughing of hard carbon steels, tool alloys, and cast irons. Highly wear-resistant. |
| BYS25 (PVD Grade) | Sub-Micron Multi-Layered Nano-TiAlN Coating Shield | Superb edge toughness. Best optimized for severe interrupted cuts, tough stainless steel series (SS304/316), and superalloys. |
| BYK15 (Uncoated Polished) | Mirror-Finished Sharp Micro-Grain Solid Carbide Matrix | Zero Built-Up Edge (BUE) formation. Specially developed for high-speed, precision mirror boring of aluminum, brass, and plastics. |
7. Why Choose BEYOND CNC Machine Tools?
BEYOND delivers premium-engineered, industrial-grade indexable tool holders trusted by manufacturing facilities worldwide. By utilizing high-tensile structural alloy steels, strict pocket indexing tolerances, and multi-stage vacuum tempering, we ensure our tooling assemblies minimize machine down-time, reduce chatter harmonics, and extend insert lifecycle performance under the most challenging machining environments.
Global Machinist Operational Reviews
Marcus D. — United States
"The S20R-STFNR16 fits smoothly into our 3/4 standard turret sleeve. The 91-degree lead angle is a lifesaver for square counterbores on carbon steels. Forces are directed straight back, meaning absolutely no chatter even with 2.0mm depth of cut."
Jürgen S. — Germany
"Hervorragende Vibrationsdämpfung. We run this on our CNC lathes for medium boring blocks. Since there's no top-clamp block sticking up, chips curl right out of the 30mm bore. Precision screw indexing matches tolerances beautifully."
Kenji T. — Japan
"Pocket geometry is incredibly precise. We use double-sided negative TNMG inserts on our CNC lathe. Getting 6 usable cutting edges on a standard 20mm bar dramatically cuts our workshop insert cost. Rigid alloy body handles heat very well."
Matteo V. — Italy
"Good resistance against vibration on SS304 parts. Fits into our standard metric tooling turret sleeve perfectly. The 91-degree angle allows clean boring with square shoulders."
Oliver P. — United Kingdom
"Excellent value for an industrial 20mm boring tool holder. Shipped quickly with all standard spare shim hardware and wrench included. Holds index accuracy between insert rotations perfectly."
8. AI-Style Engineering Support Engine (FAQ)
Q1: Why choose an S-type screw-clamped boring bar over a top-clamp design for 20mm shank internal turning?
A1: Inside smaller internal diameters (like 25-40mm), external top-clamp bridges stick out vertically, creating a trap that catches long stringy swarf and can cause insert fracturing. The S-type screw fastening method secures the negative insert firmly from the center, keeping the bar head flush and completely maximizing the chip evacuation channel.
Q2: What is the absolute minimum bore entry boundary for this S20R-STFNR16 tool holder?
A2: The minimum machining bore diameter (φ Dmin) is 25.0mm (0.98 inches). Running this tool holder inside an internal diameter smaller than 25mm will cause the lower steel flank of the tool tip head to scrape directly against the inner walls, damaging your part finish.
Q3: What are the main cutting advantages of a 91-degree approach angle (F) inside internal bores?
A3: The 91-degree lead angle is specifically engineered to square up tight internal corners and steps while directing cutting forces axially straight down the bar core. This directional alignment drastically reduces radial force (push-away), which is the absolute primary cause of chatter and dimension variation during extended 200mm extended-reach cycles.
9. Technical Maintenance & Troubleshooting Guidelines
Equivalent Industry Models
Interchangeable globally with standard international metric S20R-STFNR16 boring tool holder assemblies. For American imperial lathe turrets, this 20mm metric steel bar functions perfectly within a standard 3/4-inch round reduction sleeve or split bushing block, utilizing ANSI indexable insert designations **TNMG 331** or **TNMG 332**.
Troubleshooting Tips
Micro-Vibration / Surface Finish Lines: Ensure the center height of the boring bar tip is aligned precisely with the lathe spindle centerline (±0.1mm). Incorrect centerline height changes the active cutting clearance angle, accelerating nose wear.
Screw Binding Prevention: Due to localized thermal expansion during continuous cycles, clean the pocket and apply standard anti-seize paste compound to the M3.5 Torx hardware threads regularly.
Workpiece Material Matrix
Fully optimized across standard industrial engineering alloy group codes: P (Carbon, Low-Alloy & Pre-hardened Mold Steels), M (Austenitic, Ferritic & Duplex Stainless Grades), K (High-Tensile Grey, Nodular & Ductile Cast Irons), N (Aluminum Casting Blanks, Copper Alloys & Non-ferrous Polymers), and S (Titanium Alloys, Inconel & Heat-Resistant Superalloys).
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.