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Back Corner Rounding End Mill



What is a Back Corner Rounding End Mill? How does it work?

A back corner rounding end mill is a specialized cutting tool designed to create precise radii (rounded corners) on the backside of a workpiece.They are often used in situations where a standard corner rounding end mill won't fit due to clearance issues. These tools typically feature a flared neck and shoulder to blend the radius smoothly into the surrounding surfaces, avoiding steps or marks.

How does it work?

Setup: The end mill is mounted securely in the machine spindle.
Positioning: The workpiece is positioned so the back corner that needs rounding is accessible to the cutter.
Cutting: The end mill spins while being moved along the edge of the workpiece. It uses the radius portion of its cutting edge (and sometimes the flares) to cut away material.
Radius Creation: This cutting action creates a smooth, rounded corner on the backside of the part.

How are Back Corner Rounding End Mills manufactured?

The process generally involves several key stages:

1. Material Selection:

  • High-speed steel (HSS) or solid carbide rods are the most common materials. Carbide offers superior wear resistance and is better suited for harder materials or higher production volumes.

2. Blank Formation:

  • The rod is cut and ground to a cylindrical blank with the general shape of the end mill.

3. Flute Grinding:

  • Specialized CNC grinding machines carve out the helical flutes that form the cutting edges of the end mill. The number of flutes (often 2 or 4) influences chip removal and cutting smoothness.

Radius Grinding:

  • The precise radius shape at the tip of the tool is ground using highly accurate grinding wheels. This step defines the final radius size that the end mill will produce.

Neck and Flare Formation:

  • Additional grinding steps create the back corner rounding end mill's distinctive neck and flared shoulder, crucial for clearance and a smooth finish.

Coating (Optional):

  • Some end mills receive a performance-enhancing coating (like TiN or AlTiN) for increased wear resistance and longer tool life.

Quality Inspection:

  • Dimensions, tolerances, and surface finish are carefully checked to ensure the end mill meets specifications.


Chipbreaker End Mill

A chipbreaker end mill is a cutting tool featuring specially designed notches or geometries along its cutting edges.

Keyseat Cutter

Full radius keyseat cutters are specialized milling tools designed to create semi-circular keyseats within shafts or bores.

End Mill

An end mill is a type of milling cutter extensively used in CNC machines and manual milling machines for a wide variety of machining operations.

What sizes does Baucor manufacture Back Corner Rounding End Mill?

Common Sizes for Back Corner Rounding End Mills

  • Radius Sizes:
  • Imperial: 1/32", 1/16", 3/32", 1/8", 5/32", 3/16", etc.
  • Metric: 1mm, 2mm, 3mm, 4mm, 5mm, 6mm,etc.
  • Shank Diameter: Common shank sizes are 1/8", 1/4", 3/8", and 1/2".
  • Overall Length: Varies based on radius and shank size, but generally between 1.5" to 4".
  • Neck Length and Diameter: These will often be slightly smaller than the shank to ensure clearance.

Baucor can manufacture end mills to cater to a diverse range of milling applications, from general purpose milling tasks to the creation of intricate profiles and complex 3D shapes. 

End mills are available in a variety of types, such as square end mills for creating sharp corners, ball nose end mills for smooth contouring, and roughing end mills for rapid material removal. Suitable for materials including metals, plastics, and composites, Baucor can produce end mills in highly specialized sizes and configurations tailored to meet your specific requirements. Please contact us for detailed information on dimensions and customization options to perfectly match your milling needs.

Ball Nose End Mill

A ball nose end mill is a specialized cutting tool used in CNC machining. It features a rounded, ball-shaped tip that makes it ideal for creating curved surfaces, rounded corners, and intricate contours.

Porting Tools

Porting tools are specialized cutting and grinding tools used to modify the intake and exhaust ports within an engine's cylinder head.

Tapered End Mill

A Tapered End Mill is a cutting tool with a conical shape, where the diameter gradually decreases from the shank to the tip, used for machining angled surfaces, deep cavities, and tapered features in various materials.

An Engraving Cutter with a Radius

An Engraving Cutter with a Radius is a precision cutting tool designed for engraving and detailing, featuring a tip with a rounded radius to create smooth, curved cuts and intricate designs on various materials.

What materials are used to make Back Corner Rounding End Mill? 

Back Corner Rounding End Mills are specialized cutting tools used to create a radius on the back side of a workpiece. Here's the breakdown of their material composition:

Common Materials

High-Speed Steel (HSS):

  • Traditional material, relatively less expensive.
  • Offers good toughness and flexibility.
  • Suitable for softer materials or less demanding applications.
  • Common grades include M2, M35 (with cobalt), and M42 (even more cobalt for higher hot hardness).

Solid Carbide:

Extremely hard and wear-resistant.

Maintains sharpness over greater cutting distances and at higher speeds.

Ideal for harder materials like hardened steel and for high-volume production.

More brittle than HSS, requiring careful handling.

Less Common (but Possible) Materials

Powdered Metal (PM) Steels:

  • Offer a balance between the toughness of HSS and the wear resistance of carbide.
  • More expensive than HSS but generally cheaper than solid carbide.


  • Incredible hot hardness and wear resistance.
  • Used for very high-speed machining in specialized applications.
  • High cost and extreme brittleness limit their general use.

Lollipop cutters

Lollipop cutters, also known as undercut end mills or ball nose end mills with necks, are specialized cutting tools used for a variety of machining tasks.

Clearance Cutter Square End Mill

A clearance cutter, more commonly known as a square end mill, is a versatile rotary cutting tool used in CNC milling machines.

Corner Rounding End Mill - Double End

A Double-End Corner Rounding End Mill is a cutting tool with rounded cutting edges on both ends, used to create rounded corners or radii on the edges of a workpiece, enhancing efficiency by allowing use of both ends.

Clearance Cutter - Ball End Mill

A Clearance Cutter - Ball End Mill is a type of end mill with a rounded tip (ball end) and a reduced diameter or relieved shank, designed to provide clearance for machining intricate surfaces, deep cavities, and complex shapes while minimizing tool interference.

What coatings improve Back Corner Rounding End Mill?

Back corner rounding end mills are specialized cutting tools that add smooth radius edges to the backside of workpieces. These tools are essential in various manufacturing applications but choosing the right end mill material and coating can significantly impact their performance and longevity.

Common Coatings

  • TiN (Titanium Nitride): A versatile, all-purpose coating that improves surface hardness, reduces friction, and provides moderate heat resistance.
  • TiCN (Titanium Carbonitride): Offers even greater hardness and wear resistance than TiN, making it suitable for more abrasive materials.
  • AlTiN (Aluminum Titanium Nitride): Excels in high-temperature applications due to its superior heat resistance, making it ideal for harder materials or high-speed machining.
  • TiAlN (Titanium Aluminum Nitride): Similar properties to AlTiN, often used as an alternative based on cost and availability.
  • ZrN (Zirconium Nitride): A good choice for machining softer, non-ferrous materials like aluminum and its alloys.

Specialized Coatings

  • Diamond-like Carbon (DLC): Provides extreme hardness, wear resistance, and a very low coefficient of friction. Used for specific applications with very abrasive materials or where lubrication is difficult.
  • Multilayer coatings: Can combine the properties of different coatings (e.g., AlTiN with TiN) for tailored performance.

Important Considerations:

  • Compatibility: The coating must be compatible with the base material of the end mill (HSS, carbide, etc.).
  • Application: Choose a coating that aligns with the materials you're cutting and the machining conditions (speeds, feeds, lubrication).
  • Cost: Advanced coatings generally increase the cost of the end mill.


What machines use Back Corner Rounding End Mill?

Back Corner Rounding End Mills are primarily used in CNC (Computer Numerical Control) machines. Here's a breakdown of the most common types:

Primary Machines

  • CNC Milling Machines: These are the most common machines for back corner rounding end mills. Their precision, programmability, and automatic tool-changing capabilities make them ideal for creating complex radii in a variety of materials.
  • Types: 3-axis, 4-axis, and 5-axis CNC mills can all use back corner rounding end mills depending on the complexity of the workpiece.

CNC Machining Centers: Similar to CNC milling machines, but often with more advanced capabilities and a larger work envelope.

Less Common, but Possible

  • Manual Milling Machines: Experienced machinists can sometimes use back corner rounding end mills in manual mills, but the precision and repeatability will be less predictable compared to CNC machines.

CNC Lathes (with Live Tooling): Lathes with live tooling capabilities (rotating tools on the turret) can sometimes use back corner rounding end mills for specific applications.

Important Factors

  • Clearance: The machine must have sufficient clearance around the workpiece and spindle to accommodate the back corner rounding end mill's unique geometry.
  • Rigidity: The machine must be rigid enough to withstand the cutting forces involved, especially when working with harder materials.
  • Control: CNC control is ideal for the precise movements needed to create accurate radii with back corner rounding end mills.

Where are Back Corner Rounding End Mills used?

The world of precision machining often requires going beyond right angles and sharp edges. Back corner rounding end mills are specialized tools designed to add smooth, rounded profiles to the often overlooked backsides of workpieces. Here's where they make a difference:

Primary Applications

  • Creating Internal Radii: Back corner rounding end mills are vital for creating rounded corners on the back sides of parts where a standard corner rounding tool wouldn't have the necessary clearance.
  • Deburring and Chamfering: They can be used to remove sharp edges (deburring) or create angled bevels (chamfering) on the backside of features.
  • Improving Aesthetics and Functionality: Rounded corners reduce stress concentrations, improve part fatigue life, make parts safer to handle, and often enhance a part's overall appearance.

Which industries use Back Corner Rounding End Mill?

In the world of precision machining, sometimes a sharp edge just won't do. Back corner rounding end mills are specialized tools that transform sharp corners into smooth, radiused edges. This seemingly small detail has far-reaching benefits across several industries.

  • Aerospace: Aircraft manufacture requires numerous complex parts with internal pockets and features. Back corner rounding end mills provide the clearance to create smooth radii for weight reduction, stress concentration reduction, and improved part longevity.
  • Automotive: Engine blocks, transmission housings, and other powertrain components often have internal corners that benefit from radiusing. Smoother corners improve durability, reduce stress points, and can even influence fluid flow and lubrication.
  • Medical: Surgical implants and instruments frequently require rounded corners for safety, biocompatibility, and ease of cleaning. Back corner rounding end mills ensure these radii are precise and smooth.
  • Mold and Die Making: Molds for plastic injection or metal casting often incorporate internal radii. Adding these radii to the mold itself improves part release, reduces stress points in the molded part, and enhances the mold's lifespan.
  • General Manufacturing: Numerous industries producing machined components benefit from back corner rounding end mills. Rounded internal corners improve aesthetics, safety, and strength across a vast range of products.

End Mill Neck Relief

End Mill Neck Relief is the reduced diameter section behind the cutting edge of an end mill, designed to provide clearance and reduce tool deflection during deep cutting operations.


Reamers are a precision cutting tools used to enlarge and finish the diameter of an existing hole to a high degree of accuracy and smoothness.

Tapered Ball Nose End Mill

Tapered Ball Nose End Mill is a specialized cutting tool with a tapered body and rounded tip, ideal for 3D contouring and smooth surface finishing in CNC milling and engraving applications.

Pointed Chamfer Cutter

Pointed chamfer cutters are a type of end mill used specifically for creating chamfers – angled cuts that transition between two surfaces.

What design and engineering support does Baucor provide for Back Corner Rounding End Mill?

Design and Engineering Support from Baucor

  • Tool Selection Assistance:
  • Analyze part drawings and material properties to advise on the best end mill configurations (radius size, shank diameter, flute count, neck dimensions, material, coating).
  • Consider factors like the machine's capabilities, workpiece geometry, and desired finish.

  • Machining Parameter Optimization:
  • Provide recommended spindle speeds, feed rates, and depths of cut tailored to the specific workpiece material, machine, and desired surface finish.
  • Help customers achieve optimal material removal rates while maximizing tool life.

  • Troubleshooting and Problem Solving:
  • Help diagnose issues like excessive tool wear, chatter, poor surface finish, or dimensional inaccuracies.
  • Suggest adjustments to machining parameters, tool fixturing, or even the workpiece design itself.

  • Custom Tool Design:
  • Design and manufacture back corner rounding end mills with unique geometries, radii, or features.
  • Create highly specialized tools for applications where standard off-the-shelf end mills aren't sufficient.

  • Application Engineering:
  • Provide in-depth consultations on best practices for using back corner rounding end mills.
  • Teach customers about optimizing workholding strategies and programming techniques to get the most out of these tools.

Additional Support Possibilities

  • On-Site Visits: Send engineers to the customer's facility to observe machining operations and offer targeted advice.
  • Simulation Software: Provide or recommend software for simulating cutting processes, predicting tool wear, and preventing potential problems.
  • Training and Education: Offer webinars, seminars, or written resources on back corner rounding end mills and their applications.


Engineering Expertise, Every Step of the Way

BAUCOR offers custom manufacturing and engineering solutions tailored to your specific needs, across various industries.

Optimize Your Design for Production

BAUCOR's engineers can review your design and provide feedback to improve manufacturability, cost effectiveness, and efficiency.

Your Solution, Your Scale

Whether you need a single prototype or full-scale production, BAUCOR''s engineers are ready to collaborate with you. Contact us to discuss how we can bring your concept to life.

Tailored Solutions for BAUCOR Customers

BAUCOR specializes in providing unique manufacturing and engineering solutions designed to meet the specific needs of each client. Our expertise covers a wide range of industries and applications.

What are the design guides for Back Corner Rounding End Mill?

In manufacturing, achieving smooth, rounded edges on the backside of workpieces is often crucial. Back corner rounding end mills are the tools designed for this specific task. Understanding their construction is key to selecting the right tool and maximizing its performance.

Primary Geometric Features


  • Dictates the size of the rounded corner created on the workpiece.
  • Selected based on design requirements, stress reduction needs, and aesthetic preferences.

Shank Diameter:

  • Must be compatible with the machine tool's spindle and tool holder.
  • Larger shank diameters provide more rigidity but may restrict access to tight corners.

Neck Diameter:

  • Typically slightly smaller than the shank diameter.
  • Provides clearance behind the cutting edges to avoid interference with the workpiece.

Neck Length:

Determines the reach of the tool into recessed areas.

Longer necks may require reduced cutting parameters to avoid chatter.

Overall Length (OAL):

  • Includes the shank, neck, and cutting portion.
  • Longer lengths may require greater machine rigidity and slower speeds.

Other Design Considerations

Number of Flutes:

  • More flutes generally improve surface finish but reduce chip clearance.
  • Typically 2-4 flutes are used for back corner rounding end mills.

Helix Angle:

  • Influences chip evacuation, cutting forces, and surface finish.


HSS for softer materials and lower production runs. Solid Carbide for harder materials, high-speed machining, and longer tool life.


  • TiN, TiCN, AlTiN, and others improve wear resistance and performance in specific materials.

Important Notes:

  • Clearance: The design must ensure the tool can access the workpiece corner without the shank or holder interfering.
  • Trade Offs: Design decisions often involve trade-offs between rigidity, reach, surface finish, and material removal rate.
  • Application Specific: The optimal design is always highly influenced by the specific application needs.