Introduction to Double Chamfer End Mills and Their Machining Capabilities

Introduction to Double Chamfer End Mills

Double chamfer end mills, also known as double angle end mills, are a type of milling cutter used in CNC machining and manual milling applications. They are characterized by having cutting edges on both the end face and circumference of the cutter, allowing them to machine in two directions at once.

Double chamfer end mills provide several key benefits that make them a versatile tool for a range of milling operations:

• They can generate sharp internal and external corners, eliminating the need for multiple tools or secondary operations.
• The double cutting edges shear the material more aggressively for faster material removal rates.
• The chamfered corners allow for better chip ejection when pocketing or slotting.
• Having cutters on both the end and circumference provides more flutes for chip evacuation.
• The double angle cutting edges provide stronger teeth for more durable tool life.

In this article, we'll take a closer look at how double chamfer end mills work and where they excel in machining applications. We'll also go over tips for how to select and utilize them effectively in your jobs.

How Double Chamfer End Mills Work

Double chamfer end mills get their name from having chamfered corners on both the end cutting face and circumferential surface of the tool. This allows them to cut on both the end and periphery simultaneously.

The end cutting edges are ground at a 30-45 degree angle relative to the tool axis. Meanwhile, the peripheral edges have a standard 30-45 degree helix angle. Having positive rake angles on both sets of cutting edges allows for an aggressive shearing action when milling.

Double chamfer end mills are made from high speed or carbide tooling substrates. Carbide tools are harder and more wear resistant for machining harder materials like steel and cast iron. High speed steel tools cost less but can still tackle a wide range of materials.

They come in a range of diameters like standard end mills. Length of cut and number of flutes also vary to suit different operation requirements. The more flutes, the better chip evacuation. Longer lengths of cut provide greater reach for slotting or plunging.

Advantages of Double Chamfer End Mills

Here are some of the key benefits and capabilities of using double chamfer end mills vs. other types of milling tools:

Generate Sharp 90 Degree Internal Corners

One of the main advantages of the double chamfer end mill is its ability to create sharp 90 degree internal corners and angles.

A standard square end mill can only make a rounded internal corner dictated by the tool diameter. Double angle cutters can square off these corners since their cutting edges extend into the intersection.

This makes double chamfer end mills ideal choices for cutting precise pockets, profiles, and slots with clean internal details.

Faster Machining with Aggressive Shearing Action

The positive cutting rake angles on double chamfer end mills promote an aggressive shearing action as the tool rotates and cuts. This allows them to machine material much more efficiently compared to neutral rake cutters.

The combination of downward axial force and sharp cutting edges lets double angle end mills take very large depths of cut and bite into the workpiece aggressively. This results in much higher material removal rates.

Smooth Machined Finishes

Despite their fast metal removal, double chamfer mills also produce smooth machined finishes on flat, contoured, and pocket surfaces. The multiple flutes provide extensive chip evacuation while shearing the material cleanly.

Milling with double chamfer tools leaves uniform finishes ideal for parts that don't require secondary polishing operations. Reduced tool pressure also minimizes potential for work hardening on delicate materials.

Slotting, Pocketing, and Contouring

Double angle end mills excel at a range of common milling operations besides surface profiling. Their unique cutting geometry allows them to effectively slot, pocket, and contour as well.

The peripheral cutting edges make them suitable for full slotting comparable to slot drills. They can also clear large internal cavities and pockets thanks to the chamfered corners and double set of flutes for chip evacuation.

In contouring and 3D profiling, the end cutting edges machine crisply into vertical walls and compound angles. The sharp corners minimize material deflection under load for accuracy.

Applications of Double Chamfer End Mills

Here are some of the most common applications where double chamfer end mills are the best tool selection:

Machining Precise Pockets and Cavities

The ability to cut sharp 90 degree internal corners makes double angle end mills ideal for pocketing. They excel at clearing out square internal profiles and angles while leaving smooth flat floors.

Common examples are pockets for inserts, housings, fixtures, and dies where dimensional precision and surface finish are critical factors.

Creating Accurate Slots

Double chamfer end mills produce accurate through or blind slots with sharp corners. Machining full slot widths without leaving behind radiused edges at the bottom.

They are commonly used for cutting sliding or interface slots on machinery components like actuators, presses, and dies.

High Efficiency Milling of Flats and Contours

The aggressive material removal of double angle end mills makes them ideal for surfacing, facing, profiling, and contouring jobs where productivity is paramount.

Their shearing action and chip evacuation excel at hogging out large face areas or cutting free-form shapes efficiently.

Machining Hardened Materials

Carbide double chamfer end mills can effectively machine hardened steels up to 45-50 HRc. This allows them to cut wear resistant materials for tools, dies, and machine components without heat treating after the fact.

They are also useful on gummy and abrasive alloys prone to work hardening like stainless steels, titanium alloys, and nickel-based superalloys.

Benefits Over Standard End Mills

Comparing double angle end mills vs. standard end mills, double chamfer cutters have clear advantages in the right applications.

One Tool for Internal and External Corners

A key benefit is the ability to do both external and internal 90 degree corners with just one tool. Standard square end mills can only cut external corners and require an additional tool for internal corners.

Less Tool Pressure and Deflection

The cutting forces are distributed between the end and peripheral edges, leading to less tool pressure. Reduced deflection results in more accuracy in slotting, pocketing, and profiling operations.

Requires Lower Radial Depths of Cut

Taking lighter radial depths of cut lowers cutting forces, deflection, and heat generation. This allows double angle end mills to use more of the tool’s potential axial depth of cut for higher MRR.

Generates Less Heat

The combination of lower tool pressure and interspersed up and down milling results in lower cutting temperatures. This makes double chamfer end mills suitable for heat sensitive materials.

Maximizing Performance of Double Chamfer End Mills

Follow these tips to utilize double angle end mills effectively and get the best performance:

Run at High Spindle Speeds and Feeds

The aggressive cutting of double chamfer tools allows them to run at the upper limit of recommended SFM range. Higher speeds paired with maximum allowable chipload produces the best metal removal rates.

Reduce Radial Depths of Cut for Slotting/Pocketing

Take lighter radial DOC and allow the tool to cut more axially. This reduces tool pressure to limit deflection, work hardening, and heat generation in the cut.

Use Climb Milling for Better Results

Climb milling engages the tool cutting edges more efficiently, requiring lower forces and leaving a better finish. Conventional milling causes more rubbing and work hardening.

Apply High Pressure Coolant if Possible

HPC directed at the cutting zone can help break up chips, improve chip evacuation, and keep cutting temperatures in check for greater tool life.

Tool Selection Guidelines

Follow these basic guidelines when choosing double chamfer end mills for your application:

• Smaller diameter tools for semi-finishing and finishing cuts
• Larger diameters for high MRR roughing operations
• 4-6 flutes for optimal chip evacuation and milling forces
• Longer length of cuts for extended reach slotting applications
• Carbide tools for hardened steels and exotic alloys
• High speed steel for general purpose milling in various materials

Also take note of the tool’s shank style, reach, neck length, and coatings when selecting the optimal tool.

FAQs

Are double chamfer mills center cutting?

The majority of double angle end mills have center cutting ends. This allows them to plunge straight down similar to spot drills. Non-center cutting versions are also available for peripheral milling applications.

What angle are double chamfer end mills sharpened at?

A typical double chamfer end mill has 30-45 degree chamfer angles on the end and periphery cutting edges. The exact angle varies by tool brand and characteristics.

When should you use double chamfer vs. ball nose end mills?

Double chamfer mills are ideal for slotting, pocketing, surfacing, and profiling requiring sharp corners and shear action. Ball noses excel at 3D contouring requiring smooth rounded edges with no sharp transitions.

Can you plunge mill with double chamfer end mills?

Yes, center cutting double chamfer mills can plunge straight down like an end mill. Non-center cutting versions are limited to peripheral milling operations.

How are double angle end mills different from corner radius end mills?

Double chamfer mills cut sharp 90 degree internal corners. Corner radius (bull nose) end mills leave a small radius inside corners based on the tool diameter.

Key Takeaways

• Double chamfer end mills cut on both the end and circumference for highly efficient milling.
• They excel at pocketing, slotting, and profiling where sharp internal corners are required.
• Double angle cutters machine aggressively and evacuate chips efficiently for high MRR.
• Their shearing action produces good finishes and minimizes work hardening risks.
• Optimal speeds/feeds, depths of cut, and climb milling maximize their performance.

FAQs

What materials can you cut with double chamfer end mills?

Double chamfer mills can cut a wide range of materials including aluminum, steels, titanium, tougher alloys like Inconel, and even hardened materials up to 45-50 Rc. Tool substrate and coatings are selected based on workpiece hardness.

Do double angle end mills produce a lot of heat?

No, the reduced tool pressure and up/down direction milling characteristic of double chamfer mills results in lower cutting temperatures than end mills. This makes them suitable for heat sensitive materials.

Can these tools side mill or face mill?

Primarily intended for end milling operations, double chamfer cutters can also face mill in certain applications. However, peripheral milling should be limited to lighter depths of cut to avoid high tool stresses.