Form Radius Shearing
The internal curve wraps around the workpiece corner and shears it into a convex arc.
Mills / Radius form tools
Concave Radius Milling Cutters
What Are Concave Radius Milling Cutters and How Do They Work?
A concave radius cutter is a form-milling tool with a female, inward-curved profile along its flutes. Unlike a convex cutter that machines a concave slot, this tool shapes an outer edge or corner into a convex radius.
Single-Pass Profiling
The form can generate a 90° corner radius or 180° convex bead in one milling movement.
Consistent Form Geometry
A precision-ground profile repeats the specified radius from part to part.
Surface Transition
The cutting form blends the rounded corner into adjacent flat walls.
Key Features and Benefits of Concave Radius Milling Cutters
Single-Pass Edge Rounding
Forms a complete radius in one contouring pass instead of many small 3D ball-nose stepovers.
Repeatable Forming
Produces consistent convex radii without manual bench blending.
High Form Rigidity
Solid construction limits vibration and tool flex during radius milling.
Profile Options
Available in quarter-round 90° and half-round 180° concave forms.
Multiple Flute Configurations
Available with 2, 3, or 4 flutes to balance chip clearance across soft and hard metals.
Concave Radius Milling Cutters Specifications
| Specification | Range / Details |
|---|---|
| Radius Sizes | 1/32" to 1/2"+; metric 0.5 mm to 12 mm+ available |
| Profile Geometry | 90° quarter-round or 180° half-round concave arc |
| Flute Count | 2, 3, or 4 flutes |
| Shank Style | Straight cylindrical or Weldon shank |
| Cutting Center | Non-center cutting; side-engagement form tool |
| Tolerance | Ground to sub-micron form-radius tolerances |
Materials and Coatings Available for Concave Radius Milling Cutters
| Material / Coating | Best For | Key Advantage |
|---|---|---|
| Solid Carbide | Stainless steel, titanium, hardened steels, and cast iron. | Rigidity limits tool flex and supports convex-profile accuracy. |
| TiAlN / AlTiN Coating | Tough alloys, high-temperature materials, and dry machining. | Thermal hardness protects the internal radius lips from premature wear. |
| DLC / ZrN Coating | Aluminum, copper, brass, and non-ferrous plastics. | Low friction helps prevent built-up edge inside the concave flutes. |
Solid carbide provides form rigidity, TiAlN or AlTiN supports tough alloys and dry machining, and DLC or ZrN helps manage built-up edge in non-ferrous materials.
Which Machines Use Concave Radius Milling Cutters?
CNC Machining Centers
Run 2D outer-contour and edge-rounding toolpaths.
5-Axis CNC Mills
Follow complex 3D contours to apply convex radii along angled surfaces.
Swiss-Type CNC Lathes
Use live tooling to round outer edges on small turned components.
Applications and Industries for Concave Radius Milling Cutters
External Edge Rounding
Machines functional convex radii on external corners of frames and housings.
Half-Round Bead Milling
Forms convex half-round beads and decorative ribs along structural channels.
Turbine and Vane Profiling
Shapes rounded leading and trailing edges on aerodynamic blades and vanes.
Medical Device Ergonomics
Rounds outer edges on hand-held surgical instruments and medical-equipment housings.
Frequently Asked Questions About Concave Radius Milling Cutters
How does a concave radius cutter differ from a convex radius cutter?
A concave cutter has an internal curved flute that creates an outer convex edge or bead. A convex cutter has an external curved profile that machines an internal concave radius or slot.
How can a concave milling cutter reduce CNC cycle time?
A ball nose end mill forms a radius with many small stepover passes. A concave form cutter cuts the complete radius in one 2D contouring pass.
How do I set tool offsets for a concave radius cutter?
Program from the cutter's major diameter or center point relative to the radius arc, and use the manufacturer's drawing to locate the gauge distance from the shank to the radius center.
Can concave radius cutters be used on internal holes?
They are primarily intended for external edges, steps, and outer perimeters. Corner rounding or back corner rounding end mills are used for entrance and exit edges of internal holes.
Does Bauron manufacture custom concave radius cutters?
Bauron can engineer non-standard radius dimensions, neck-clearance lengths, multi-radius geometries, and application-specific coatings from part drawings.
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Design and Engineering Support
Bauron provides design and engineering support for custom radius dimensions, neck clearances, multi-radius geometries, and application-specific coatings. Share part drawings and machining requirements for technical review.
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