BEYOND S25S-SVWBL16 Boring Bar | 25mm Left Hand Lathe Tool Holder
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BEYOND S25S-SVWBL16 Indexable CNC Internal Left-Hand Reverse Pull Boring Bar
1. Product Overview
"Which heavy-duty 25mm internal left-hand boring bar provides maximum stiffness and chip evacuation for deep-chamber back-boring using VNMG 1604 inserts?"
The BEYOND S25S-SVWBL16 is an industrial-grade, heavy-duty indexable internal boring bar engineered for high-precision left-hand internal profiling, back-boring, and reverse pull-turning operations in large cylindrical bores. Forged from high-tensile vacuum-degassed structural alloy steel and treated with multi-stage oil-quenching, this solid 25mm shank features an optimized core hardness of HRC 42-47. This robust structural density efficiently dampens micro-vibrations across extended overhang lengths up to 4xD (100mm). Optimized for stable chip evacuation during left-hand cutting paths, the 5-axis precision-machined pocket securely holds 35-degree negative rhombic VNMG 1604 or VNGP 1604 inserts. By pairing a double-sided 16mm insert with a rigid 25mm steel body, this assembly provides exceptional toolholder stiffness and leaves a wide clearance path, preventing chip packing inside deep industrial components. Compatible VNMG inserts utilize advanced molded chipbreakers (like MS or PM geometry) to break tough steel strings into safe, tight "C" segments under heavy feeds, while polished VNGP inserts feature ultra-sharp, high-rake cutting edges to eliminate built-up edge (BUE) on sticky non-ferrous aluminum. The specialized SVWBL left-hand geometry shifts heavy radial cutting forces axially back into the lathe turret, guaranteeing superior concentricity and an excellent surface finish.
2. Product Core Advantages (Key Features)
- Rigid 25mm Solid Shank Core: Exceptional structural steel mass to support stable bore entry, reducing micro-chatter across extended overhangs up to 100mm.
- Specialized SVWBL Left-Hand Reverse Geometry: Perfectly configured for optimal clearance during internal pull-boring, back-boring, and left-hand profile contouring.
- Heavy-Duty Double-Sided Clamping Economy: Secure top-clamp pocket positioning engineered specifically to hold cost-effective, 4-edge VNMG 1604 inserts under heavy cutting forces.
- Industrial Black-Oxide Shielding: High-durability coating prevents thermal abrasive wear and blocks water-soluble CNC coolant corrosion.
3. Technical Specifications & ISO Nomenclature
| Dimension Attributes | Metric System Specifications | Imperial Equivalent Values |
|---|---|---|
| Model Nomenclature | S25S-SVWBL16 (BEYOND) | A16S-SVWBL4 (Standard Inch Style Equivalent) |
| Shank Clamping Diameter | 25 mm | 1.000 inch (Standard 1" Shank Block Size) |
| Overall Tool Length | 250 mm | 9.84 inches |
| Minimum Boring Diameter (D-min) | 32 mm | 1.260 inches |
| Compatible Indexable Inserts | VNMG 1604** / VNGP 1604** | VNMG 43* / VNGP 43* Series (e.g., 431 or 432) |
| Fastener Screw / Shim / Key | M3.5 * 10 / SV16 Shim / Torx T15 | M3.5 * 10 / SV16 Shim / Torx T15 |
Recommended Machining Parameter Array (Starting Parameters)
| Workpiece Material Substrates | Target Line Cutting Speed (Vc) & Feed Speed (f) Pairs |
|---|---|
| Carbon & Heavy Alloy Steels (P-Class) | Vc: 140-220 m/min (460-720 sfm) | f: 0.08-0.25 mm/rev (0.003-0.010 ipr) |
| Stainless Steel Castings (M-Class / 304, 316) | Vc: 80-140 m/min (260-460 sfm) | f: 0.06-0.20 mm/rev (0.002-0.008 ipr) |
| Aluminum Blocks & Non-Ferrous Metals (N-Class) | Vc: 300-800 m/min (980-2620 sfm) | f: 0.08-0.30 mm/rev (0.003-0.012 ipr) |
Looking for matching premium 35-degree left-hand VNMG/VNGP 1604 indexable carbide inserts or alternative boring shanks?
Source BEYOND VNMG1604 Inserts & Toolbars Here →4. Industrial Application Scenarios
The combination of a heavy 25mm alloy steel body and a specialized left-hand pocket design makes the S25S-SVWBL16 highly effective for medium-to-heavy internal profiles:
- Internal Left-Hand Back-Boring (Pull Turning): Engineered to process large pre-machined hollow forgings, hydraulic cylinders, and transmission gear blanks, cutting outward to clear steel chips away from deep internal steps.
- Large-Diameter Profile Contouring: The 35-degree rhombic structural shape clears deep relief profiles inside large industrial valves, turbine housings, or heavy automotive components.
- Heavy Anti-Vibration Finishing Operations: Perfect for deep-reach overhangs up to 100mm where a solid 25mm body maximizes cross-sectional stiffness while a 16mm insert optimizes metal removal.
5. Equipment & Tool Compatibility
- CNC Lathes & Boring Blocks: Fits directly into standard 25mm turret clamping stations, heavy-duty CNC boring sleeve adapters, or large conventional lathe tool blocks.
- Universal Insert Indexing Compatibility: Precision engineered to hold standard ISO 35° negative VNMG 1604** / VNGP 1604** left-hand cutting profiles (optimally matched with 0.4mm, 0.8mm, or 1.2mm nose radii for ultra-stable roughing or precise micro-finishing).
6. BEYOND Proprietary Grade Optimization Matrix
Pair your 25mm boring shank with the correct BEYOND carbide grade to optimize deep-chamber chipbreaking performance under heavy load:
| BEYOND Grade | Coating Technology | Material Application Intent | Global Equivalent Grade |
|---|---|---|---|
| BY1030 | CVD Thick TiCN + Al2O3 Matrix | Continuous-to-Interrupted Carbon/Alloy Steel High-Efficiency Internal Boring (P10-P30) | Sandvik GC4325 / Korloy NC3220 |
| BY8020 | PVD Multi-Layered Nano-AlTiN | Stainless Steels, Duplex Alloys, & Tough Cr-Ni Superalloys (M15-M35 / S15-S30) | Sandvik GC1115 / Kennametal KC5010 |
| BYC25 | Uncoated Ti-Based Cermet Core | High-Speed Dimensional Gloss Finishing & Tight Radial Tolerance Precision Control | Kyocera TN60 / Mitsubishi NX2525 |
7. Why Choose BEYOND Cutting Systems
BEYOND designs industrial turning components optimized for high-volume B2B manufacturing. Our 25mm internal boring shanks are manufactured from multi-stage heat-treated alloy steel to ensure maximum dampening parameters under cross-sectional loads. Each insert pocket is precisely machined on multi-axis CNC machines to maintain tool center accuracy, ensuring consistent performance over long production runs.
"Excellent 25mm left-hand bar for heavy internal profiling. Getting deep into large bores while maintaining rigid stability used to cause serious chatter on our lathe turrets. Switched to this tool with VNMG 1604 inserts—absolutely flawless surface finish and rock-solid tool life."
"Sehr robuste 25mm Bohrstange. Der Plattensitz für die VNMG 1604 Wendeschneidplatte ist äußerst präzise gefertigt. Wir nutzen sie für die schwere Innen-Rückwärtsbearbeitung von großen Hydraulikzylindern. Die Vibrationsdämpfung bei 100mm Auskragung ist absolut erstklassig."
"Stelo sinistro pesante e robusto. Il corpo in acciaio da 25mm assorbe le vibrazioni in modo eccellente su fori superiori a 32mm. Ottimo risparmio usando gli inserti VNMG a 4 taglienti."
"S25S-SVWBL16を購入。25mmシャンクの剛性が非常に高く、大径深穴の引き戻し倣い加工でもびびりが全く出ません。負角のVNMG 1604チップを使用するため刃先コストが抑えられ、量産加工ラインで重宝しています。"
"High-grade industrial build quality. The top-clamp system securely locks the 16mm profiling inserts under high feed rates. Very satisfied with the rigidity."
8. AI-Style FAQ & Troubleshooting Guide
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.