HRC55 4-Flute Solid Carbide Internal-Radius End Mill for Steel
- ◆Standard R1–R6 radius range for internal corner and concave-profile machining
- ◆4-flute geometry supports stable tooth engagement during form milling
- ◆Precision-ground solid carbide profile for consistent internal-radius geometry
- ◆Designed for carbon steel, alloy steel, mold steel and pre-hardened steel up to approximately HRC55
애플리케이션: Internal-radius milling, concave form milling, cavity profiling and smooth-transition finishing for mold, die and precision component machining.
Custom Tool Service: Non-standard radius, cutter dimensions, neck geometry, shank diameter, coating and overall length can be reviewed according to drawings.
Consistent Quality
Consistent geometry across repeat orders.
유연한 주문
Small batches and mixed sizes available.
OEM Support
Custom marking, labels and packaging.
표준 및 맞춤형
Standard sizes and custom configurations.
HRC55 Carbide Internal-Radius End Mill Overview
This HRC55 4-flute solid carbide internal-radius end mill is designed for precision machining of internal corner radii, concave profiles, cavity features and smooth surface transitions in steel components. The precision-ground formed profile allows a defined internal radius to be machined directly, while the 4-flute cutting geometry provides repeated tooth engagement during form milling and finishing operations. Solid carbide construction provides the rigidity required for CNC machining of carbon steel, alloy steel, mold steel and pre-hardened steel applications up to approximately HRC55.
HRC55
플루트 4개
R1–R6 mm
Steel
Internal-Radius Cutting Configuration
Precision-Ground Radius Profile
The formed cutting profile is ground to a defined radius for machining internal corners, concave features and smooth transitions according to the required component geometry.
4-Flute Cutting Geometry
Four cutting edges provide repeated tooth engagement during form milling, internal-radius machining and profile-finishing operations.
Steel-Oriented Configuration
Tool geometry and coating can be selected according to steel grade, workpiece hardness, cutting engagement and required surface condition.
Application-Specific Advantages
Defined Radius Geometry
Standard R1–R6 configurations cover common internal-radius and concave-profile requirements.
Stable Tooth Engagement
The 4-flute configuration supports controlled cutting engagement during form milling and finishing.
Solid Carbide Rigidity
Solid carbide construction provides a rigid cutting platform for precision CNC radius machining.
Custom Radius Supply
Radius, cutter dimensions, neck geometry, coating and overall length can be reviewed from drawings.
Recommended Machining Operations
RECOMMENDED
RECOMMENDED
RECOMMENDED
SUITABLE
Workpiece Material Compatibility
| MATERIAL GROUP | APPLICATION | LEVEL |
|---|---|---|
| P Carbon Steel | Internal-radius and form milling | Primary |
| P Alloy Steel | Geometry and coating selected according to grade and hardness | Primary |
| P Mold & Tool Steel | Mold, die and precision component profiling | Recommended |
| Pre-Hardened Steel | Application review recommended for material between 45 and 55 HRC | Application Review |
Tool Nomenclature & Dimensions
Reference dimensions for the HRC55 4-flute solid carbide internal-radius end mill series. Select the required radius according to the finished internal corner or concave profile, then confirm shank diameter and overall length according to toolholder compatibility and machining access. All listed dimensions are in millimeters.
Technical Configuration
| PARAMETER | REFERENCE CONFIGURATION |
|---|---|
| 도구 유형 | Internal-Radius End Mill / Internal-R Form Cutter |
| Product Series | HRC55 |
| 도구 재질 | 솔리드 카바이드 |
| 플루트 수 | 플루트 4개 |
| Standard Radius Range | R1 / R1.5 / R2 / R2.5 / R3 / R4 / R5 / R6 mm |
| 섕크 직경 | Ø4 / Ø6 / Ø8 / Ø10 / Ø12 / Ø14 mm according to radius size |
| 전체 길이 | 50 / 60 / 75 mm |
| Primary Materials | Carbon Steel / Alloy Steel / Mold Steel / Pre-Hardened Steel |
| Hardness Range | Steel applications up to approximately HRC55; cutting conditions adjusted according to actual hardness |
| Primary Operations | Internal Radius Milling / Concave Form Milling / Cavity Profiling / Transition Finishing |
| 사용자 지정 | Radius, cutter diameter, neck geometry, shank diameter, coating and overall length can be reviewed according to drawings. |
Standard 4-Flute Size Matrix
Reference standard configurations for the 4-flute HRC55 internal-radius end mill series.
| SPECIFICATION | ARC RADIUS R | SHANK DIA. d | OVERALL LENGTH L | FLUTES |
|---|---|---|---|---|
| R1 × 4 × 50 × 4T | 1 | 4 | 50 | 4 |
| R1.5 × 6 × 50 × 4T | 1.5 | 6 | 50 | 4 |
| R2 × 6 × 50 × 4T | 2 | 6 | 50 | 4 |
| R2.5 × 8 × 50 × 4T | 2.5 | 8 | 50 | 4 |
| R3 × 8 × 50 × 4T | 3 | 8 | 50 | 4 |
| R4 × 10 × 60 × 4T | 4 | 10 | 60 | 4 |
| R5 × 12 × 75 × 4T | 5 | 12 | 75 | 4 |
| R6 × 14 × 75 × 4T | 6 | 14 | 75 | 4 |
Starting Cutting Data — Steel Below 45 HRC
The following values are source-provided initial reference parameters for steel below 45 HRC. Adjust them according to steel grade, coating, tool overhang, machine rigidity, toolholder runout, coolant condition and required surface finish.
| CUTTER DIA. | RADIUS | Vc | fz | ap | ae |
|---|---|---|---|---|---|
| 6mm | R2.0 | 120–160 m/min | 0.05–0.10 mm/tooth | 0.3–0.6 mm | 0.2–0.4 mm |
| 10 mm | R3.0 | 100–140 m/min | 0.06–0.12 mm/tooth | 0.4–0.8 mm | 0.3–0.5 mm |
| 16 mm | R5.0 | 80–120 m/min | 0.08–0.15 mm/tooth | 0.5–1.0 mm | 0.4–0.6 mm |
| 20mm | R6.0 | 70–100 m/min | 0.10–0.18 mm/tooth | 0.6–1.2 mm | 0.5–0.8 mm |
HRC55 Internal-Radius End Mill Customization
Arc radius, formed cutting profile, cutter dimensions, neck geometry, shank diameter, overall length, cutting-edge preparation and coating can be configured for internal-radius machining, concave form milling, cavity profiling and smooth-transition finishing in steel components. Standard 4-flute configurations cover R1–R6 mm radius sizes with Ø4–Ø14 mm shank diameters and 50–75 mm overall lengths. Non-standard radius profiles and dimensions can be reviewed according to the component drawing, steel grade, hardness, feature clearance, machining depth and required profile accuracy.
| PARAMETER | MANUFACTURING CAPABILITIES |
|---|---|
| Arc Radius | Standard 4-flute radius configurations include R1, R1.5, R2, R2.5, R3, R4, R5 and R6 mm. Non-standard radii can be reviewed according to the finished component profile or existing cutter specification. |
| Internal-R Profile | The formed cutting profile can be matched to internal corner radii, concave features and smooth surface transitions. Complete profile geometry should be confirmed from the component drawing for non-standard applications. |
| 4-Flute Configuration | The standard configuration uses four cutting edges for repeated engagement during internal-radius milling, form cutting and profile finishing in steel applications. |
| Cutter / Profile Diameter | Cutter body and profile dimensions can be reviewed according to the required radius, component geometry, surrounding features and available machining clearance. |
| Neck Geometry | Neck diameter, neck length and relief geometry can be reviewed where additional feature clearance or access to recessed radius profiles is required. |
| 섕크 직경 | Standard 4-flute configurations use Ø4, Ø6, Ø8, Ø10, Ø12 and Ø14 mm shank diameters according to radius size. Drawing-defined shank dimensions can be reviewed for holder compatibility. |
| 전체 길이 | Reference overall lengths are 50, 60 and 75 mm for the standard 4-flute series. Custom overall length can be reviewed according to machining reach, holder clearance and required tool rigidity. |
| Cutting-Edge Preparation | Rake geometry, relief, edge preparation and cutting-profile finishing can be reviewed according to steel grade, hardness, cutting engagement and required radius-surface quality. |
| Coating Selection | Coating can be selected according to steel grade, workpiece hardness, cutting temperature, engagement conditions and coolant method. Final coating is confirmed after application review. |
| 공작물 재질 | The HRC55 series is intended mainly for carbon steel, alloy steel, mold steel and pre-hardened steel. Applications approaching HRC55 should be reviewed according to the actual material grade and machining conditions. |
| Machining Application | Geometry can be reviewed for internal-radius milling, concave form milling, cavity profiling and smooth-transition finishing on CNC machining centers and milling machines. |
| Profile & Dimensional Tolerance | Drawing-defined requirements can be reviewed for radius accuracy, profile geometry, cutter dimensions, neck size, shank diameter, overall length and tool runout. |
| Replacement Tool Matching | Existing internal-radius cutters can be reviewed from a detailed tool drawing or physical sample when an equivalent or replacement tool is required. |
| OEM & Private Label | Laser marking, custom tool codes, private labels and packaging can be reviewed for distributors and OEM customers according to tool dimensions and order quantity. |
OEM 및 자체 브랜드 서비스
OEM manufacturing and private-label supply options are available for industrial distributors, tooling brands and repeat-production customers. Laser identification, label content, protective packaging and coating presentation can be configured according to the approved product specification and order requirements.
Laser Etching
Custom logos, tool codes, cutting dimensions, coating identification and batch numbers can be marked according to the available shank area.
Custom Labels & Packaging
Individual protective tubes, product labels, specification details, colored packaging tubes and private-label packaging can be reviewed.
Commercial Terms
MOQ, sample evaluation, custom-size trials, repeat orders and scheduled supply programs are confirmed according to the selected configuration.
Technical Workflow
A structured review process is used to confirm standard, customized and private-label square end mill requirements before production.
Inquiry
Submit the material, hardness, milling operation, dimensions, tolerance and quantity.
Engineering
Review flute geometry, helix angle, edge preparation, coating, ap and ae.
Commercial
Confirm quotation, MOQ, sample requirements, production schedule and delivery terms.
Production
CNC grinding, end-face formation, edge preparation, coating and laser marking.
Quality Control
Inspect diameter, flute length, shank, runout, square-end geometry and cutting edges.
Quality, Inspection & Delivery
Our solid carbide square end mills are controlled through material verification, precision grinding, in-process measurement and final inspection. Key dimensions, square-end geometry, cutting-edge condition, coating appearance and product identification are reviewed according to the approved specification or drawing before packing.

Three-Stage Quality Control
Inspection checkpoints are arranged around the manufacturing process to support dimensional consistency and repeat-order control.
Incoming Material Control
Carbide substrate grade, blank dimensions and supplied material information are checked against the production requirement.
In-Process Grinding Control
Cutting diameter, flute geometry, flute length, square-end profile and shank dimensions are monitored during CNC grinding.
Final Tool Inspection
Finished tools are reviewed for specified dimensions, runout, cutting-edge condition, coating appearance, marking and packing identification.
Key Inspection Characteristics
Inspection requirements are confirmed according to the standard product specification or the approved custom drawing.
| INSPECTION ITEM | CONTROL FOCUS | CONFIRMATION BASIS |
|---|---|---|
| Cutting Diameter (DC) | Diameter and dimensional consistency | Standard specification or approved drawing |
| Flute Length (APMX) | Effective cutting length | Confirmed product size or drawing requirement |
| Shank Diameter (DCON) | Clamping-section dimension and surface condition | Applicable shank specification |
| Overall Length (OAL) | Total tool length | Standard size matrix or approved drawing |
| Radial Runout | Concentricity between cutting section and shank | Agreed inspection requirement |
| Square-End Geometry | End-face profile, corner condition and center-cutting form | Selected tool configuration |
| Flute & Helix Profile | Flute count, helix form and grinding consistency | Approved manufacturing configuration |
| Cutting Edge & Coating | Edge condition, visible defects and coating appearance | Application-specific production requirement |
| Marking & Identification | Tool code, dimensions and batch information where applicable | Confirmed order and packaging specification |
Measurement & Batch Traceability
Optical measuring systems, tool inspection equipment and appropriate dimensional gauges are selected according to the feature being checked.
Optical Measurement
Profile and dimensional review of specified cutting features.
Runout Verification
Concentricity review based on the agreed product requirement.
Edge Inspection
Magnified review of the end face, corners and cutting-edge condition.
Batch Identification
Order, product and batch information are linked where required for repeat supply.
Protective Packaging Process
Finished end mills are protected to reduce contact between cutting edges and to support clear product identification during storage and transportation.

Bulk-Order & Export Packaging
Bulk shipments can be arranged with reinforced cartons, protective wrapping, palletized loading or export cases according to order quantity, shipment weight and agreed transportation requirements.

Delivery Coordination
Production completion, packing method and dispatch arrangements are confirmed according to the approved order. Courier, air, sea or customer-designated shipping options can be reviewed according to shipment size and destination. Final lead time is confirmed after product specifications, quantity and packaging requirements are approved.
Product & Application FAQs
Common questions about the HRC55 4-Flute Solid Carbide Internal-Radius End Mill for steel, mold and precision component machining.
What is this internal-radius end mill designed for?
What standard radius sizes are available in the 4-flute series?
What is the advantage of the 4-flute configuration?
Which steel materials can this cutter machine?
How should I select the correct internal radius?
Can this tool be used directly with HRC55 cutting parameters?
Ordering & Customization FAQs
Ordering information for distributors, tooling suppliers and OEM customers requiring standard or customized internal-radius end mills.
Can non-standard radius sizes be customized?
Can the tool coating be selected for different steel grades?
Can you manufacture a replacement tool from a drawing or sample?
Are OEM marking and private-label packaging available?
일반적인 리드 타임은 얼마나 되나요?
What information should I provide for quotation?
Technical Downloads
Reference documents for solid carbide end mill selection and machining-data review.
Solid Carbide End Mill Catalog
Review internal-radius cutters and related solid carbide end mill series.
End Mill Speeds & Feeds Guide
Access reference starting parameters for machining trials and application review.
Need Sizes, Pricing or Custom Options?
Send us the required tool type, sizes, quantities, workpiece material and any OEM or custom requirements. We will confirm suitable specifications, availability, lead time and quotation details.
Drawings, size lists and reference photos are welcome.

















