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SM-4R 4-Flute Corner Radius End Mill

Engineered for chatter-free radius shoulder profiling and edge blending in gummy stainless steels. Variable helix & pitch, U-flute chip evacuation, and TiAlN+AlCrN composite coating deliver seamless roughing-to-finishing on curved transitions.

Solid Carbide 4 Flutes Variable Helix & Pitch U-Flute Design TiAlN+AlCrN Coated Radius Shoulder Finishing
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SM-4R 4-Flute Corner Radius End Mill
SM-4R 4-Flute Corner Radius End Mill
SM series 4 flute corner radius end mill for stainless steel variable helix pitch
Variable helix and pitch flute geometry detail

Procurement & Commercial Terms

MOQ1 pc (sample/stock) | 50 pcs (OEM/bulk)
Lead Time3–5 days (standard stock) | 10–15 days (custom/OEM)
InventoryR0.2–R2.0 in stock. R2.5–R3.0 available on short notice.
Custom OptionsExtended cutting length, slim shanks, alternative coatings, laser marking, private packaging
PackagingIndividual vacuum blister + anti-rust paper | Rigid export cartons (50/100 pcs)
ShippingDHL/FedEx/UPS for samples | Air/Sea freight for bulk. Incoterms: EXW, FOB, CIF, DDP

Advanced Geometry for Stainless Steel Radius Profiling

Variable Helix & Pitch

Eliminates harmonic chatter during radius shoulder profiling of gummy stainless steels. Irregular flute spacing disrupts resonant frequencies for smooth curved engagement.

U-Flute Wide Gullet

Maximizes chip evacuation space to prevent recutting and built-up edge during radius corner slotting. Critical for maintaining surface quality in 304/316 stainless.

TiAlN + AlCrN Coating

Composite PVD layer combines hardness with low friction. Withstands >1100°C during continuous radius profiling, preventing thermal softening and chip adhesion.

4-Flute Radius Stability

Larger core diameter minimizes deflection on radius transitions. Four cutting edges distribute load evenly, maintaining tight tolerances on curved shoulders.

SM-4R Corner Radius Dimensions 

SM-4R Corner Radius Dimensions

ModelD (mm)R (mm)d (mm)H (mm)L (mm)Stock
SM-4R-1-0.2-3-4-5010.24350●
SM-4R-1.5-0.2-4.5-4-501.50.244.550●
SM-4R-2-0.2-6-4-5020.24650●
SM-4R-2-0.5-6-4-5020.54650●
SM-4R-3-0.2-8-4-5030.24850●
SM-4R-3-0.5-8-4-5030.54850●
SM-4R-3-1-8-4-50314850●
SM-4R-4-0.2-10-4-5040.241050●
SM-4R-4-0.5-10-4-5040.541050●
SM-4R-4-1-10-4-504141050●
SM-4R-5-0.5-13-6-5050.561350●
SM-4R-5-1-13-6-505161350●
SM-4R-6-0.2-15-6-5060.261550●
SM-4R-6-0.5-15-6-5060.561550●
SM-4R-6-1-15-6-506161550●
SM-4R-8-0.5-20-8-6080.582060●
SM-4R-8-1-20-8-608182060●
SM-4R-8-2-20-8-608282060●
SM-4R-10-0.5-25-10-75100.5102575●
SM-4R-10-1-25-10-75101102575●
SM-4R-10-2-25-10-75102102575●
SM-4R-12-0.5-30-12-75120.5123075●
SM-4R-12-1-30-12-75121123075●
SM-4R-12-2-30-12-75122123075●

● In stock | ○ Make-to-order | Full range: D3.0–D16.0 with R0.2–R3.0. Tolerance: D≤12 → 0~-0.020mm | D>12 → 0~-0.030mm. R → ±0.01mm. CAD/STEP files available.

Note: Optimized for radius shoulder profiling, edge blending, and radius corner slotting in stainless steel. U-flute geometry requires adequate coolant/MQL flow to evacuate gummy chips effectively.

Stainless Steel Radius Milling Guide

WorkpieceGrade ExamplesSuitabilityRadius Profiling Notes
Austenitic Stainless304, 316, 321◎ ExcellentHigh ductility requires variable pitch to prevent chatter. U-flute prevents BUE on radius transitions.
Martensitic/PH17-4PH, 420, 440C◎ ExcellentHigher hardness benefits from composite coating thermal resistance during edge blending.
Duplex/Super Duplex2205, 2507◎ ExcellentHigh strength requires reduced speeds. Variable helix maintains stability on curved shoulders.
Carbon/Alloy Steel1045, 4140, P20○ GoodEfficient but over-specified. Use GM series corner radius for better cost efficiency.

◎ = Very Suitable | ○ = Limited | ✗ = Not Recommended | SM Series is engineered specifically for stainless steel radius shoulder challenges. For general steels  <55HRC, please use our PM Series Corner Radius. For hardened steels >55HRC, please use our HM Series Corner Radius.

CAM Setup & Radius Shoulder Parameter Guidance

Recommended Parameters (304/316)
  • ✅ Radius Shoulder Finishing: ae = 0.02D–0.04D, ap = 0.3D–0.5D, Vc = 40–70 m/min
  • ✅ Edge Blending: Use ae = 0.01D–0.02D, ap = 0.1D–0.2D for seamless transitions
  • ✅ Roughing-to-Finishing: Start at ap = 0.3D, finish at ap = 0.05D without tool change
  • ✅ Use climb milling exclusively to minimize work hardening and improve surface finish
Radius-Specific Best Practices
  • ⚠️ Maintain constant chip load on curved paths. Never let the tool dwell to prevent severe work hardening
  • ⚠️ Use MQL or high-pressure coolant to flush gummy chips from corner radius flutes
  • ⚠️ Ensure runout <0.005mm. Uneven load distribution accelerates wear on radius juncture
  • ⚠️ For radius corner slots, use arc lead-ins to avoid shock loading the cutting edge

Typical Stainless Steel Radius Applications

🏥 Medical Implants & Surgical Tools

Radius shoulder profiling of 316L orthopedic components and hygienic instrument housings. Variable pitch ensures burr-free edges on blended curves.

🍽️ Food & Beverage Hygienic Fittings

Radius corner profiling of 304/316 tank interiors, conveyor frames, and pipe fittings. U-flute design prevents chip recutting in curved transitions.

🧪 Chemical & Valve Components

Radius shoulder finishing of duplex 2205 valve bodies and chemical reactor fittings. TiAlN+AlCrN coating prevents nickel/chromium smearing.

Factory Production & Quality Control

5 axis CNC grinding and PVD coating line for SM corner radius end mills

Manufacturing Process & QA Steps

  • 🔹 Substrate: Ultra-fine tungsten carbide (0.4μm grain) optimized for high toughness in gummy material radius profiling
  • 🔹 Grinding: 5-axis CNC maintains variable helix/pitch accuracy ±0.3° & radius tolerance ±0.01mm
  • 🔹 Coating: Imported target PVD TiAlN+AlCrN (3.0–4.0μm) applied at 400-450°C for optimal adhesion
  • 🔹 Passivation: Controlled sandblasting + micro-edge honing balances fracture resistance and sharpness for radius transitions
  • 🔹 Traceability: Each batch includes laser-etched SKU, grinding date, coating certificate, and QC report. Available upon request.

Frequently Asked Questions

Radius profiling on gummy stainless steels creates uneven cutting forces that trigger harmonic chatter. Variable helix and pitch disrupt resonant frequencies, ensuring smooth engagement on curved shoulders and eliminating vibration marks.

Yes. The U-flute wide gullet provides exceptional chip evacuation for aggressive radius roughing, while sandblasted passivation and TiAlN+AlCrN coating maintain edge integrity for fine finishing, eliminating tool changes.

The composite layer combines TiAlN's hardness with AlCrN's low friction and oxidation resistance. This prevents chip adhesion and built-up edge during continuous radius profiling, extending tool life by 30-50% in austenitic and duplex steels.

Maintain constant chip load using arc toolpaths on radius shoulders, ensure adequate coolant/MQL flow, and use climb milling exclusively. The SM series variable pitch geometry inherently reduces cutting forces, minimizing heat and plastic deformation.

Request Quote for SM-4R 4-Flute Corner Radius End Mill

Specify your diameter range, material, and monthly volume. We respond with pricing, stock status within 24 hours.

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