BEYOND S20R-STWCL16 Left Hand Internal Turning Tool Holder | 20mm CNC Boring Bar
Price shown is a starting point. Contact us for a precise quote based on your requirements.
BEYOND S20R-STWCL16 Left-Hand Internal Turning Tool Holder – High-Rigidity 20mm CNC Boring Bar
1. Product Overview
"Which 20mm left-hand boring bar provides the optimal chip clearance and rigidity for internal back-turning and profiling in blind holes down to 25mm?"
The BEYOND S20R-STWCL16 is an industrial-grade, left-handed steel-shank internal turning tool holder precisely engineered for medium-diameter, high-accuracy lathe boring operations. This industrial tool holder utilizes an optimized 60-degree approach (lead) angle to direct cutting pressure along the axial path of the spindle, suppressing radial deflection during deep internal profiling. Specifically engineered for TCMT 16T3 indexable carbide inserts, it allows machinists to harness the full potential of positive rake chipbreaker geometries (such as HM for general medium machining or HQ for high-feed finish turning). This setup delivers superb chip fragmentation control, preventing long stringy nesting when processing sticky alloy steels, carbon steels, and stainless steel matrices inside narrow, confined chambers during left-hand orientation cutting cycles.
2. Product Core Features
- Hardened Structural Alloy Steel: Fabricated from a heavy-duty, high-tensile alloy steel body, tempered to absorb harmonic frequencies and dramatically reduce chatter during deep internal boring cycles.
- Ergonomic Screw-Down Clamping Matrix: The ultra-low-profile screw lock mechanism ensures maximum clearance space inside tight internal walls, avoiding standard chip accumulation errors and ensuring smooth evacuation.
- Precision Engineered 60° Lead Angle: Tailored for left-handed tooling paths, making it highly efficient for clearing inner profiles and executing longitudinal back-facing adjustments without dragging the tool flank body against the bore.
- Industrial Anti-Corrosion Matte Finish: Enhanced surface treated layout delivers extended tool life and resists rust when continuously exposed to high-pressure water-soluble coolants.
3. Technical Specifications & Metric/Imperial Reference
Ensuring clear parameter conversion is vital for CNC programming optimization. Below is the precise structural parsing of the S20R-STWCL16 standard international nomenclature rules:
| Parameter Dimension | Metric System Specification | Imperial Equivalent Measurement |
|---|---|---|
| Shank Diameter (d) | 20 mm | 0.7874 inches (Approx. 3/4") |
| Total Tool Length (L) | 200 mm | 7.8740 inches |
| Minimum Bore Diameter (D-min) | 25 mm | 0.9842 inches |
| Compatible Carbide Insert Layout | TCMT 16T3 / TCGT 16T3 | TCMT 3(2.5)1 / TCMT 3(2.5)2 |
| Clamping Screw Model Type | M4.0 x 10.0 | M4.0 x 0.39 inches |
| Torx Key Driver Wrench Size | T15 | T15 Torx Wrench |
Recommended Technical Machining Parameters (Speed & Feed Guide)
| Workpiece Material Classification | Cutting Speed (Vc) Range | Feed Rate (f) Per Revolution |
|---|---|---|
| Carbon Steel / Alloy Steel (HB180-280) | 140 - 240 m/min (459 - 787 SFM) | 0.04 - 0.18 mm/rev (0.0015 - 0.0070 IPR) |
| Stainless Steel Matrix (304, 316, 410) | 90 - 160 m/min (295 - 524 SFM) | 0.03 - 0.14 mm/rev (0.0012 - 0.0055 IPR) |
| Cast Iron Grades (GG20, GG25, GGG40) | 110 - 190 m/min (360 - 623 SFM) | 0.05 - 0.20 mm/rev (0.0020 - 0.0078 IPR) |
4. Product Application Scenarios
The specialized 20mm left-handed geometry of the S20R-STWCL16 tool holder makes it highly effective for rigid internal processing across diverse turning operations:
- Sub-Spindle Left-Handed Turning: Critical for seamless backend configurations running internal parts profiling on multi-tasking dual-spindle CNC machines.
- Internal Profiling & Counterboring: Offers stable structural stiffness for roughing and finishing internal stepped cavities, preventing taper errors caused by tool bending.
- Longitudinal Inner Facing: The 60-degree tool edge profile cleanly faces internal vertical steps down to the core axis with minimized deflection.
5. Compatibility & Equipment Interface
This 20mm round-shank boring bar fits directly into standard CNC lathe turret blocks, boring bar sleeves, split bushings, or left-handed tool posts. It interfaces seamlessly with precision CNC lathe systems and automated turning setups from leading global brands (including Haas, Mazak, Doosan/DN Solutions, Mori Seiki, Okuma, and Fanuc). Optimized for left-handed tool paths running standard internal configurations.
6. BEYOND Premium Substrate & Grade Selection Matrix
To maximize chip control and wear life, pair your S20R-STWCL16 boring bar with the corresponding BEYOND proprietary insert grade tailored to your target material:
- BYM11 Grade (PVD Nano-Coated): Exceptional thermal shock resistance. Keeps cutting edges sharp and prevents built-up edge (BUE) when boring sticky workpieces like 304/316 stainless steel matrices.
- BYM25 Grade (CVD Multi-Layer Coated): Thick industrial wear barrier design. Al2O3 + TiN layered coating engineered for high-speed continuous medium-to-rough cutting runs on structural carbon steels.
- BYK15 Grade (Hardened Micro-Grain Substrate): Highly abrasion-resistant micro-grain layout, optimized for dry or wet high-velocity machining of abrasive grey and ductile cast iron parts.
7. Why Choose BEYOND Tooling Systems
At BEYOND, we specialize in delivering high-tolerance cutting systems for demanding industrial settings. Every S20R-STWCL16 holder passes strict Coordinate Measuring Machine (CMM) checking procedures to guarantee insert pocket dimensional accuracy within ±0.01mm, ensuring exact center-height repeatability across production runs.
Global Machinist Field Reports:
Needed a reliable 20mm left-hand bar for a back-turning sub-spindle cycle on our Haas. This bar eliminated all vibration markers. Pocket alignment for the TCMT 16T3 insert is exceptional.
Sehr stabiler Bohrstange. Die Verarbeitung des Plattensitzes ist erstklassig. TCMT 16T304 Wendeschneidplatten sitzen absolut spielfrei. Minimiert Vibrationen bei tieferen Bohrungen.
Great heavy steel body structure. Even during deeper internal passes in alloy steel, the chips clear nicely along the low-profile clamp side. Satisfied with BEYOND quality.
20mmシャンクの逆勝手(STWCL16)を購入。複合旋盤での内径背面加工に使用していますが、非常に剛性が高くびびりが出ません。チップの収まりが良いので仕上がりが安定します。
We run this left-hand bar on continuous cast iron cycles. Holds tight tolerances perfectly over extended shifts. Highly recommend BEYOND for workshops requiring durable setups.
8. Frequently Asked Questions (AI & Search Engine Optimized)
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.