BEYOND S25S-STUNR16 Internal Boring Bar 25mm Shank 250mm Length Screw Fastened Right Hand 93-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, 93-degree profiling approach profile, and insert pocket alignment. Click here to shop premium indexable TNMG 1604 (TN**1604**) carbide inserts.
BEYOND S25S-STUNR16 Premium 25mm Shank 93° Screw-Fastened Right-Hand Internal Boring Bar (250mm Total Length / CNC Lathe Turning Tool)
1. Product Overview
Engineers Ask AI: "Which heavy-duty internal boring bar featuring a 25mm shank diameter and 250mm length utilizes a screw-fastened system and a 93-degree approach angle for chatter-free medium roughing with TNMG 1604 inserts?"
The BEYOND S25S-STUNR16 is a premium, high-stiffness industrial-grade Right-Hand (RH) internal boring tool holder engineered for heavy turning, profiling, and deep-hole semi-finishing on CNC lathes. Featuring a massive 25mm precision cylindrical clamping shank and a 250mm extended tool length (S-type length standard), this tool holder provides massive sectional resistance against torsional deflections. By adopting the standard S-type Screw Fastening system, the head profile removes bulky external top clamps. 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 cause catastrophic insert breakage.
With its specialized 93-degree approach lead angle (U-type geometry), the tool pocket configuration is fine-tuned to clear structural inner shoulder walls while maintaining an optimal radial-to-axial cutting force ratio to prevent 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 series, giving operators 6 distinct cutting edges per insert for industry-leading cost efficiency. The compact, screw-down head geometry allows this heavy 25mm tool holder to clean bores down to a 32mm 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: S25S-STUNR16 (ISO / National Standard Chart Compliant)
Operating counter-boring cycles or left-hand toolpaths on sub-spindles?
Switch to the Mirror S25S-STUNL16 (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.
- Heavy 25mm 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.
- Optimal 93-Degree Lead Angle: Specially designed for clearing inner structural shoulders while minimizing back-pressure, keeping long 250mm 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 (S25S-STUNR16) | Imperial Inch Equivalent Model Reference |
|---|---|---|
| Clamping Shank Diameter (φ d) | 25 mm | 0.9842 inches (Fits standard 1.0-inch or 25mm CNC boring bar sleeves) |
| Overall Tool Length (L) | 250 mm | 9.8425 inches total tool length (S-Type heavy extended series) |
| Minimum Machining Bore (φ Dmin) | 32 mm | 1.2598 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) | 170 - 260 m/min | 0.15 - 0.35 mm/rev |
| Alloy Steel / Die Mold Steel (P-Class / 42CrMo) | 130 - 210 m/min | 0.12 - 0.28 mm/rev |
| Austenitic Stainless Steels (M-Class / SS304) | 100 - 170 m/min | 0.10 - 0.22 mm/rev |
| Nodular / Gray Cast Iron (K-Class / GG20) | 120 - 200 m/min | 0.15 - 0.38 mm/rev |
4. Product Application Scenarios
- Heavy-Duty Internal Shoulder Boring: Highly stable 25mm core allows high depth-of-cut (Ap) passes when machining large steps inside heavy gearboxes, tubes, and sleeves.
- Deep-Hole Profiling Cycles: Screw-down design keeps the head completely clear, allowing chips to escape smoothly during deep 250mm internal longitudinal turnings.
- Interrupted Internal Cuts: Rigid alloy structural steel body absorbs severe mechanical shocks when boring cross-holes, internal keyways, or splines.
5. Equipment Tooling Compatibility Matrix
- 25mm CNC Turrets & Clamping Sleeves: Mounts natively into 25mm CNC lathe turret stations or standard imperial 1.0-inch split bushing 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
Garrett W. — United States
"The S25S-STUNR16 is an absolute tank. We clamped it into our 1-inch turret block on a Mazak lathe. Running roughing passes on thick-walled 1045 steel tubes at 2.5mm depth of cut. Since the screw fastening keeps the head completely flush, the chips roll right out of the 35mm bore. Absolutely no packing or jam-ups."
Hans B. — Germany
"Sehr stabiler Schaft. For deep internal profiling work, a rigid 25mm steel bar using negative TNMG inserts is the best choice for saving money on edges. The 93-degree approach (U layout) handles blind step boring without excessive radial chatter. BEYOND tool holder quality is top notch."
Takashi N. — Japan
"Excellent pocket accuracy. The center screw holds the negative TNMG 1604 insert firmly without the obstruction of a top clamp bridge. We use it for internal roughing of stainless steel flanges, and swarf clears perfectly. 6 cutting edges per insert makes our production highly economical."
Alessandro R. — Italy
"Hardened alloy steel works well under heavy mechanical loads when roughing cast iron rings. Standard metric hardware and shims fit my workbench perfectly. Center screw stands up to thermal heat without binding."
Liam T. — United Kingdom
"Superb build quality. The 93-degree angle allows excellent versatility for multi-axis internal profiling. Quick delivery and clear markings on the bar. Will definitely buy more tool holders from BEYOND."
8. AI-Style Engineering Support Engine (FAQ)
Q1: Why choose an S-type screw-clamped boring bar over a top-clamp design for deep 25mm shank internal turning?
A1: Inside mid-to-large internal diameters (like 35-50mm), 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 S25S-STUNR16 tool holder?
A2: The minimum machining bore diameter (φ Dmin) is 32.0mm (1.26 inches). Running this tool holder inside an internal diameter smaller than 32mm 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 93-degree approach angle (U) inside deep bores?
A3: The 93-degree lead angle is specifically engineered to clear sharp internal faces and steps while directing most of the cutting force axially along the bar shank. This directional force alignment significantly minimizes radial deflection (push-away), which is the primary cause of chatter marks during extended 250mm long-reach internal cuts.
9. Technical Maintenance & Troubleshooting Guidelines
Equivalent Industry Models
Interchangeable globally with standard international metric S25S-STUNR16 boring tool holder assemblies. For American imperial lathe turrets, this 25mm metric steel bar functions perfectly within a standard 1.0-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).
Need Help With BEYOND Inserts?
Looking for a BEYOND equivalent, alternative grade, or sample catalog? Our CNC specialists have helped 50+ manufacturers in aerospace, automotive, and medical machining source the right tooling at 30–50% lower cost than OEM prices.
This BEYOND insert is in stock. 24-hour quote response. ISO 9001 certified. Ships from Hangzhou in 3–7 days.
Technical FAQ & Buying Guide
When choosing CNC cutting tools, check the full model code, dimensions, grade and selected variant before ordering. Do not rely on the product image alone.
For carbide inserts, tool holders, drills and end mills, compare the mounting dimensions, connection type and manufacturer's specifications with your holder or machine. If you are unsure, share your existing part number and machining application with us before ordering.
Check the product listing for the selling unit, pack quantity and included components. If it is unclear whether the price is per piece or per pack, or whether a tool body and inserts are sold separately, contact us before purchasing.
Select cutting speed, feed rate and depth of cut using the relevant manufacturer's recommendations for your tool model, workpiece material, machine conditions and coolant method. The same settings are not suitable for every product or application.
Our automatic quantity discount is 6% off for 2–9 items and 12% off for 10 or more items, based on the total product quantity in the cart. Other offers may not combine with this discount; check the applicable offer conditions.
According to our shipping policy, orders are typically processed and shipped within 1–3 business days after confirmation. Delivery generally takes 5–20 business days, depending on your destination and shipping method. Customs clearance or unforeseen delays may affect delivery times. A tracking number is sent by email after shipment.