Home>Products>Milling>Solid Carbide End Mills>Specialized End Mills

SRM Series Carbide Concave Radius End Mill

Specialized internal R (concave radius) end mills for precision undercut and fillet machining. Available in two optimized versions: TiSiN Coated for Steel (≤38HRC) and DLC Coated for Aluminum. 4-flute design ensures superior surface finish.

Solid Carbide 4 Flutes Internal R Geometry R0.2mm - R8.0mm Steel & Aluminum Versions Undercut Specialist
View Specifications Request Bulk Pricing
SRM Series Carbide Concave Radius End Mill
SRM Series Carbide Concave Radius End Mill
DLC coating for aluminum

Procurement & Commercial Terms

MOQ1 pc (sample/stock) | 50 pcs (OEM/bulk)
Lead TimeSame day dispatch (standard stock) | 7–10 days (custom/OEM)
InventoryR0.2mm–R8.0mm full range in stock (Steel & Aluminum versions). Ready to ship.
Coating OptionsSteel Version: TiSiN Coating (≤38HRC) | Aluminum Version: DLC Coating
Custom OptionsExtended lengths, specific radii, laser marking, OEM branding
PackagingIndividual plastic tubes + anti-rust paper | Rigid export cartons (50/100 pcs)
ShippingDHL/FedEx/UPS for samples | Air/Sea freight for bulk. Incoterms: EXW, FOB, CIF, DDP

SRM Concave Radius Specifications (4-Flute)

Two Versions Available:  Steel Version (TiSiN Coated) for steel ≤38HRC | Aluminum Version (DLC Coated) for aluminum, copper, brass

SRM Concave Radius Specifications

ModelR (mm)D (mm)d (mm)L (mm)Stock
SRM-R0.2-3.8-4-500.23.8450● In Stock
SRM-R0.3-3.4-4-500.33.4450● In Stock
SRM-R0.4-3.2-4-500.43.2450● In Stock
SRM-R0.5-3-4-500.53450● In Stock
SRM-R0.6-2.8-4-500.62.8450● In Stock
SRM-R0.7-2.6-4-500.72.6450● In Stock
SRM-R0.75-2.5-4-500.752.5450● In Stock
SRM-R0.8-2.4-4-500.82.4450● In Stock
SRM-R1-2-4-5012450● In Stock
SRM-R1-4-6-5014650● In Stock
SRM-R1.5-3-6-501.53650● In Stock
SRM-R2-2-6-5022650● In Stock
SRM-R2-4-8-6024860● In Stock
SRM-R2.5-3-8-602.53860● In Stock
SRM-R3-2-8-6032860● In Stock
SRM-R3-4-10-60341060● In Stock
SRM-R3.5-3-10-603.531060● In Stock
SRM-R4-2-10-60421060● In Stock
SRM-R4.5-3-12-604.531260● In Stock
SRM-R5-2-12-60521260● In Stock
SRM-R5.5-3-14-705.531470● In Stock
SRM-R6-4-16-70641670● In Stock
SRM-R8-4-20-70842070● In Stock

● All sizes in stock | Radius tolerance: ±0.01mm | Diameter tolerance: D≤6 → 0~-0.020mm | D>6 → 0~-0.030mm. CAD/STEP files available.

Concave Radius (Internal R) Application: SRM Series is specifically engineered for internal fillet machining, undercut profiling, and concave surface finishing. Available in two coating versions: TiSiN for steel (≤38HRC) and DLC for aluminum/non-ferrous. The 4-flute design ensures superior surface finish.

Two Optimized Versions for Different Materials

Steel Version (TiSiN Coated)

  • Coating: TiSiN (Titanium Silicon Nitride)
  • Hardness Range: ≤38 HRC
  • Best For: Stainless steel (304/316/17-4PH), carbon steel, alloy steel
  • Key Benefits: High heat resistance, wear resistance, prevents built-up edge

TiSiN coating provides excellent heat resistance and wear resistance for steel machining up to 38HRC. Ideal for internal fillet machining in stainless steel molds and components.

Aluminum Version (DLC Coated)

  • Coating: DLC (Diamond-Like Carbon)
  • Material: Aluminum, copper, brass, graphite
  • Key Feature: Ultra-low friction coefficient (<0.1)<>
  • Benefits: Zero material adhesion, 3-5x tool life extension

DLC coating provides ultra-low friction to prevent aluminum and copper adhesion. Essential for precision internal R profiling in non-ferrous materials with mirror-like finish.

Why Choose SRM Concave Radius End Mills?

Internal R Geometry

Specialized concave radius design enables machining of internal undercuts and fillets impossible with standard end mills. Essential for complex mold features.

4-Flute Precision

4-flute design provides superior surface finish and higher feed rates compared to 2-flute tools. Ideal for precision internal radius profiling.

Dual Coating Options

Choose TiSiN for steel (≤38HRC) or DLC for aluminum. Each coating optimized for specific material properties and cutting conditions.

Undercut Capability

Lollipop geometry enables machining of internal undercuts and concave surfaces. Critical for mold/die manufacturing and complex 3D features.

Material Compatibility Guide

Steel Version (TiSiN Coated)
Workpiece MaterialHardnessSuitabilityNotes
Stainless Steel (304, 316, 321)≤38 HRC◎ ExcellentPrimary application. TiSiN prevents built-up edge. Use moderate speeds with flood coolant.
Carbon Steel / Alloy Steel≤38 HRC◎ ExcellentGeneral steel machining. High wear resistance.
17-4PH Stainless≤38 HRC◎ ExcellentPrecipitation hardening steel. 4-flute design ensures smooth fillet finish.
Aluminum / Copper-✗ Not RecommendedUse Aluminum Version (DLC). TiSiN not optimized for non-ferrous.
Aluminum Version (DLC Coated)
Workpiece MaterialHardnessSuitabilityNotes
Aluminum (6061, 7075, 5052)-◎ ExcellentPrimary application. DLC prevents adhesion. Use high RPM with air blast.
Copper / Brass / Zinc-◎ ExcellentDLC coating prevents smearing. Ideal for electrical connectors.
Graphite / Carbon-◎ ExcellentIndustry standard for graphite electrodes. No coating contamination.
Steel / Hardened Steel>25 HRC✗ Not RecommendedDLC coating fails rapidly in steel. Use Steel Version (TiSiN).

◎ = Excellent | ✗ = Not Recommended |        SRM Series offers two specialized versions. Choose based on your workpiece material.

Typical Applications for SRM Concave Radius End Mills

Mold & Die Manufacturing

Internal fillet machining of stainless steel molds for food processing, pharmaceutical, and consumer goods. Eliminates manual deburring and polishing.

Medical Implants & Devices

Precision internal radius machining of stainless steel surgical instruments and orthopedic implants. Mirror-finish concave surfaces meet strict biocompatibility standards.

Aluminum Heat Sinks

Undercut profiling of aluminum heat sinks and electronic enclosures. DLC coating ensures burr-free surfaces with zero adhesion.

CAM Setup & Machining Guidance

Steel Version Parameters (TiSiN)
  • ✅ Stainless 304/316: Vc = 60–100 m/min, fz = 0.03–0.08 mm/tooth, ae = 0.2D–0.4D
  • ✅ Carbon Steel: Vc = 80–120 m/min, fz = 0.04–0.10 mm/tooth, ae = 0.2D–0.4D
  • ✅ Use climb milling exclusively for smooth concave finish
  • ✅ Use flood coolant for heat management
Aluminum Version Parameters (DLC)
  • ✅ Aluminum 6061: Vc = 400–800 m/min, fz = 0.05–0.15 mm/tooth, ae = 0.3D–0.5D
  • ✅ Copper/Brass: Vc = 200–400 m/min, fz = 0.03–0.10 mm/tooth, ae = 0.2D–0.4D
  • ✅ Use climb milling for smooth finish
  • ✅ Use air blast or MQL for chip evacuation
Best Practices for Concave Radius Tools
  • ⚠️ Minimize overhang - use shortest possible tool length for rigidity
  • ⚠️ Use trochoidal toolpaths - reduces radial engagement and prevents chatter
  • ⚠️ Avoid dwell - never let tool stop while engaged; materials work-harden quickly
  • ⚠️ Runout<0.005mm<>- essential for maintaining coating integrity
  • ⚠️ Use adaptive clearing - maintains constant chip load in concave profiling
  • ⚠️ Select correct version - Steel (TiSiN) for steel, Aluminum (DLC) for non-ferrous

Factory Production & Quality Control

Concave radius end mill grinding and quality inspection

Manufacturing Process & QA Steps

  • 🔹 Substrate: Ultra-fine grain carbide optimized for concave radius grinding
  • 🔹 Grinding: 5-axis CNC grinding ensures precise concave radius geometry and radius accuracy ±0.01mm
  • 🔹 Coating Options: TiSiN for steel version, DLC for aluminum version - applied via PVD process
  • 🔹 Inspection: 100% visual, laser, and coating thickness inspection. Radius profile verified with optical comparator
  • 🔹 Traceability: Batch tracking with laser marking. ISO 9001 certified quality management.

Frequently Asked Questions

Concave radius end mills (also called internal R or lollipop end mills) are specialized tools for machining internal concave surfaces, fillets, and undercuts. The 4-flute SRM series is available in two versions: TiSiN coated for steel (≤38HRC) and DLC coated for aluminum.

Steel version features TiSiN coating optimized for materials ≤38HRC with high heat resistance. Aluminum version features DLC coating with ultra-low friction to prevent material adhesion. Both use 4-flute design for superior surface finish.

Yes. The SRM steel version with TiSiN coating is engineered for stainless steel (304/316/17-4PH) and other steels ≤38HRC. The 4-flute design provides superior surface finish for internal fillet machining.

Yes. While we stock R0.2mm to R8.0mm in both steel (TiSiN) and aluminum (DLC) versions, we can manufacture custom radii, extended lengths, and specific shank diameters upon request. OEM branding available for bulk orders (MOQ 50+ pcs).

Request Quote for SRM Series Carbide Concave Radius End Mill

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

ISO 9001 Certified Factory
Export Packaging Standard
Technical Support Available

🔒 Information used only for quotation. No third-party sharing.

Related Products

Explore our curated selection of complementary tools

STM Series Carbide T Slot end mill 4 Flutes

STM Series Carbide T Slot end mill 4 Flutes

4-flute T-slot mills for worktable & fixture machining. Two versions: TiSiN coated for steel (≤38HRC···

View Specs
SCM Series Carbide Chamfer End Milll 3 Flute

SCM Series Carbide Chamfer End Milll 3 Flute

3-flute chamfer mills for deburring & edge profiling. Two versions: TiSiN coated for steel (≤38HRC),···

View Specs
SDM Series Carbide Dovetail End Mill Cutter 4 Flutes

SDM Series Carbide Dovetail End Mill Cutter 4 Flutes

4-flute dovetail mills for precision slot machining. Two versions: TiSiN coated for steel (≤38HRC), ···

View Specs

Technical Resources

Explore related tools and machining guides to improve efficiency and tool life

How to Prevent Edge Chipping in Carbide End Mills When Machining Stainless Steel (7 Proven Solutions)

Machining stainless steel with carbide end mills can be challenging due to edge chipping, leading to tool failure, poor finishes, and downtime. This g···

2025-04-01 1097 views
What is the Use of SNMG Insert?

Discover the applications, features, and advantages of SNMG inserts in CNC turning. Learn how to select the right carbide insert for steel, cast iron,···

2025-09-06 1146 views
Ball Nose End Mills for Aerospace Parts: Performance and Surface Finish Explained

Explore how ball nose end mills improve performance and surface finish in aerospace part machining. Learn about material choice, coatings, and applica···

2025-07-28 1050 views

Ready to Improve Your Machining Performance?

Contact our experts today for a free quote or technical consultation.

Get a Free Quote