BEYOND S20R-SCKNR12 Internal Boring Bar 20mm Shank 200mm Length Screw Clamped Right Hand 75-Degree CNMG 1204 Lathe Turning Tool Holder
Price shown is a starting point. Contact us for a precise quote based on your requirements.
⚠️ 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, 75-degree heavy roughing approach profile, and negative insert pocket alignment. Click here to shop premium indexable CNMG 1204 (CN**1204**) double-sided carbide inserts.
BEYOND S20R-SCKNR12 Premium 20mm Shank 75° Screw-Fastened Right-Hand Internal Boring Bar (200mm Total Length / Heavy 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-clamped system and a 75-degree approach angle for heavy internal roughing with double-sided negative CNMG 1204 inserts?"
The BEYOND S20R-SCKNR12 is a premium, ultra-high stiffness industrial-grade Right-Hand (RH) internal boring tool holder specifically engineered for heavy-duty turning, large-depth roughing, and interrupted internal profiling on CNC lathes. Featuring a massive 20mm precision cylindrical clamping shank and a 200mm extended tool length (R-type length standard), this tool holder provides exceptional cross-sectional resistance against extreme bending moments and torsional forces. By adopting the specialized S-type Screw Fastening system for negative inserts, the head profile completely removes bulky upper clamping plates or external bridge mechanisms that typically jam metal swarf. This streamlined design opens up a completely unobstructed chip flute pathway, making it highly exceptional for deep internal roughing where compact metal swarf accumulation would otherwise trap heat, score the bored wall, and cause sudden insert failure.
With its specialized 75-degree approach lead angle (K-type geometry), the tool pocket configuration is fine-tuned to balance cutting forces smoothly between axial and radial planes, drastically strengthening the insert cutting edge against sudden fracture. This unique force distribution allows for aggressive chip loads and heavy feed rates during extended-reach internal cycles. It is custom-machined to host highly rigid, double-sided 80-degree diamond negative indexable inserts, specifically the industry-standard CNMG 120404 / CNMG 120408 / CNMG 120412 series, giving operators 4 distinct working cutting edges per insert for superior cost efficiency on high-volume production lines. The compact, screw-down head geometry allows this heavy 20mm tool holder to clean bores down to an optimized 25mm minimum bore diameter. Combined with targeted double-sided chipbreaker geometries (such as premium negative -PM/-DM profiles 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-SCKNR12 (ISO / National Standard Chart Compliant)
Operating counter-boring cycles or left-hand toolpaths on sub-spindles?
Switch to the Mirror S20R-SCKNL12 (Left Hand) Tool Bar →2. Product Core Advantages
- Low-Profile S-Type Screw Clamping: Locks the negative insert securely through its center hole. Eliminates bulky external clamps, ensuring zero chip nesting and flawless evacuation inside narrow bores.
- Ultra-Rigid 20mm Solid Alloy Core: Hardened to HRC 42-45 to actively absorb mechanical harmonics, completely eliminating tool deflection during heavy internal cutting passes.
- Heavy-Load 75° Lead Angle: Balances mechanical cutting forces efficiently, relieving radial pressure to prevent micro-chatter lines during heavy-duty internal roughing cycles.
- Double-Sided 4-Edge Cost Reduction: Custom engineered for negative 80° diamond CNMG 1204 inserts, delivering 4 working cutting edges per insert to cut your workshop's consumable costs by up to 50%.
- Industrial Black Oxide Barrier: Treated with a high-temperature chemical oxidation coat to resist severe abrasive chip friction and protect precision insert pocket indexing.
3. Technical Specification Parameters & Model Comparison
| Technical Blueprint Field | Metric Blueprint Value (S20R-SCKNR12) | Imperial Inch Equivalent Model Reference |
|---|---|---|
| Clamping Shank Diameter (φ d) | 20 mm | 0.7874 inches (Fits standard 20mm CNC round boring sleeves or 3/4-inch turret bushings) |
| Overall Tool Length (L) | 200 mm | 7.8740 inches total tool length (R-Type industrial extended deep reach series) |
| Minimum Machining Bore (φ Dmin) | 25 mm | 0.9842 inches entry clearance circle line for structural safety |
| Compatible Indexable Insert Sizing | CNMG 120404 / CNMG 120408 / CNMG 120412 | CNMG 431 / CNMG 432 / CNMG 433 (Double-sided negative standard) |
| Matching Fasteners & Spares Included | Hardened Shim, Shim Screw, Center Insert Lock 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) | 140 - 220 m/min | 0.15 - 0.35 mm/rev |
| Alloy Steel / Die Mold Steel (P-Class / 42CrMo) | 110 - 180 m/min | 0.12 - 0.30 mm/rev |
| Austenitic Stainless Steels (M-Class / SS304) | 80 - 140 m/min | 0.10 - 0.22 mm/rev |
| Nodular / Gray Cast Iron (K-Class / GG20) | 100 - 170 m/min | 0.15 - 0.38 mm/rev |
4. Product Application Scenarios
- 75-Degree Heavy Internal Roughing: The 75-degree lead angle optimizes chip thickness and protects the insert corner radius, allowing massive material removal rates in steel forgings.
- Severe Interrupted Boring Cycles: The rigid 20mm alloy core combined with flat negative pocket seating easily absorbs heavy impact loads when boring across cross-holes or multi-splined inner diameters.
- Extended deep-reach boring profiling: 200mm extended length allows deep cavity longitudinal boring inside large cylinder liners and structural mechanical blocks without chatter lines.
5. Equipment Tooling Compatibility Matrix
- 20mm / 3/4-inch CNC Turrets: Fits smoothly into standard metric 20mm boring block stations or standard imperial 3/4-inch round split-sleeve reduction block sets.
- ISO Standard Size-12 Negative Inserts: Precision-machined pocket seat perfectly anchors all standard 80° diamond negative inserts designated by global codes **CNMG 1204--**.
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-SCKNR12 functions perfectly in our 3/4 CNC turret block. Running heavy roughing passes with negative CNMG 1204 inserts on this 20mm bar is incredibly stable. The 75-degree approach angle splits the cutting pressure brilliantly."
Jürgen S. — Germany
"Phänomenale Steifigkeit. We run this for massive internal roughing cycles on carbon forgings. Because it uses the S-type screw method for CNMG negative inserts, there is no top clamp to block the bore path. Chips spiral right out of the channel."
Kenji T. — Japan
"Pocket geometry is incredibly precise for negative inserts. Being able to run heavy-duty double-sided CNMG 1204 inserts with 4 cutting edges on a standard 20mm internal bar saves our shop a massive amount of money."
Matteo V. — Italy
"Great dampening properties on interrupted cuts for tough alloy blocks. The 75-degree lead prevents sudden insert corner fractures perfectly. High-quality hard plating on the pocket body."
Oliver P. — United Kingdom
"Top tier industrial tool holder. Shipped complete with hardened seat shims and wrenches. Holds indexing repeatability perfectly after rotating worn CNMG edges."
8. AI-Style Engineering Support Engine (FAQ)
Q1: Why choose an S-type screw-clamped boring bar for heavy negative CNMG inserts instead of a top clamp?
A1: Inside tighter bores (25mm-45mm), traditional top clamp mechanisms stick up too far, catching long stringy chips and causing catastrophic tool packing or insert breakage. The S-type center screw locks the thick negative CNMG insert firmly from within its bore hole, maintaining a completely flush head profile for maximum chip evacuation room.
Q2: What is the absolute minimum bore entry boundary for this S20R-SCKNR12 tool holder?
A2: The absolute minimum machining bore diameter (φ Dmin) is 25.0mm (0.984 inches). Running this tool holder inside any bore smaller than 25mm will cause the steel clearance flank beneath the pocket to scrape heavily against the workpiece wall, ruining your dimensional accuracy.
Q3: What role does the "K" approach angle play regarding cutting performance and tool life?
A3: The "K" signifies a 75° approach lead angle. Unlike a 95° bar which pushes forces radially, the 75° orientation spreads the cutting pressure across a longer section of the insert edge, maximizing strength and protecting the tip during high-feed roughing or heavily interrupted cuts.
9. Technical Maintenance & Troubleshooting Guidelines
Equivalent Industry Models
Interchangeable globally with standard international metric S20R-SCKNR12 internal boring tool holder assemblies. For American imperial lathe turrets, this 20mm metric steel bar functions smoothly within standard 3/4-inch round split bushings or block adapters, utilizing standard ANSI negative indexable insert designations **CNMG 431** or **CNMG 432**.
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 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.