Everything You Need to Know About The Mechanics of High Feed End Mills

The milling operation is nowadays completely automated. A big milling machine is equipped with rotary cutters and drills to remove material from a particular workpiece.

Because of the virtually limitless variety of drill bits and milling ends available, the milling process may produce essentially anything, including gun components, circuit boards, jewelry, and much more.

What Are End Mills?

End Mills are used in milling, profiling, contouring, slotting, counterboring, drilling, and reaming applications to create shapes and holes in a workpiece.

In a CNC machine, milling cutters, also known as end mills, are employed. Specialized software is utilized to deliver automated milling instructions, often known as a ‘toolpath,’ to the machine, which subsequently cuts away a design in the stock material.

CNC machines perform several tasks in a small space and in a short amount of time. Hydraulic systems and hydraulic press machinery play a critical part in generating compressive force using a hydraulic cylinder.

What Is a High Feed End Mill?

High-feed end milling is a technique that provides results up to three times faster than traditional procedures. It was first used in the die and mold business and is a machining technology that combines a shallow depth of cut with a high feed per tooth, resulting in increased metal removal rates and the ability to produce more components.

Cutting forces are directed axially towards the machine spindle, resulting in improved stability, saving time and fewer vibrations, increasing tool life.

Properties of High Feed End Mills

A High Feed End Mill is a high-efficiency milling (HEM) instrument with a unique end profile that allows the tool to enhance feed rates by utilizing chip thinning drastically.

These tools are designed to work with a very shallow axial depth, allowing the cutting action to occur along the curved edge of the bottom profile. It enables a variety of occurrences:

  1. Because of the low lead angle, most of the cutting force is carried axially back into the spindle. This results in less deflection since less radial force pulls the cutter away from its center axis.
  2. The bottom edge’s extended curved contour creates a chip thinning effect, allowing for higher feed rates.
  3. Other Phenomena as a Result of the Bottom Edge’s Curved Geometry.

The bottom edge’s curved form also allows for the following events to take place:

  1. Adding a programmable radius to a CAM toolpath.
  2. During facing surgeries, scallops develop.

Properties of High Feed End Mills

Scallop Management

Scallops are a cusp of material that is left behind by cutting instruments with curved profiles. Two primary factors determine scallop height and breadth:

  • Axial Depth of Cut
  • Radial Depth of Cut

High Feed End Mills tools are often accompanied by vibration. When operating these tools at deep cutting depths to achieve high metal removal rates, productivity can sacrifice cutting tool corners and machine life.

High Feed End Mills are a simple variant of a traditional end mill because it uses a circular insert shape instead of a traditional parallelogram or square indexable insert.


Some mills can plunge directly into the material, like a drill bit. This is especially true for end mill versions, but only if the manufacturer has enough space to cut in that direction underneath the tool.

Helical Interpolation

The milling cutter can be combined with helical interpolation to quickly and easily create holes with larger diameters. This technique uses all three axes (X, Y, Z) to move simultaneously. This tool is inserted into the material without a starting hole. It starts with a spiral and moves to the final depth to completely remove the material from the hole.

Edge Strength

These provide the strongest cutting edge available for carbide inserts. This strength is useful when working with heavy cuts or when trying rough cuts in unstable conditions. When cutting with long-reach tools, round indexable inserts are more resistant to tool deflection and chatter. This means the speed and feed can be increased without the risk of chipping inserts.

Number of Edges

Depending on the size of the insert and the depth of the cut, a round insert can provide a valid index of 4-8. This is at least twice the total material removal and cutting time of a normal parallelogram or square. This advantage reduces travel to tool stores looking for new inserts, reduces the number of inserts in the warehouse, and reduces cutting-edge costs.

Low Power Metal Removal

The strength of the round inserts allows for feed rates not possible with 90 degree cutting tools, allowing even lighter machines to perform aggressive roughing. The key to the round inserts used is the deeper the cut, the thicker the chips, and the more horsepower.


Using round indexable inserts for roughing opens new possibilities in preparing for semi-finishing or finishing cuts. When roughing with a 90-degree mill, a “staircase” remains each time someone steps down. The resulting non-uniform surface creates non-uniform pressure on the semi-finished product. The direct transition from roughing to finishing is out of the question as this impacts the tool and causes different deflections.


High Feed Milling Machine is a machining process that combines a low cutting depth (DOC) with a high feed rate per tooth up to 2.0 mm. This combination maximizes the amount of metal removed from the part and increases the number of parts completed in each amount of time.

  • The HFM mechanism is formulated on the “chip thinning” effect. The chip thickness depends on the angle of entry of the cutter. A milling cutter with an inlet angle of 90 ° has a feed of 0.2 mm per tooth, producing chips with a thickness of only 0.2 mm, which has no advantage in thinning the chips.
  • Low cutting resistance is another advantage of HFM. The milling inlet angle determines the direction of cutting resistance. The 90 ° milling cutter creates a cutting force that acts perpendicular to the spindle, exerting incredible pressure on the tool. With a 45 ° cutter, the cutting force acts on the spindle at a 45 ° angle.
  • The hydraulic pressing machines cut with the bottom of the insert rather than the side. It ensures that the cutting force is roughly parallel to the spindle, and the tool is subjected to minimal side forces.

Scallop Management in High Feed End Mill


Shape Acceleration

From a tool life and productivity standpoint, the High Feed Milling Cutter is used to machine steel, cast iron (CARBFeed Steel), stainless steel, and difficult-to-machine alloys (CARBFeed Inox). Set the highest standards, the same applies to hardening (CARBFeed Hard). New performance peaks have been achieved by optimally adapting macro and micro shapes to the application areas of their respective tools.

Short Machining Time and High Feed Rate

Milling shape, substrate, coating, and cutting edge machining are specially developed for the materials to be machined and compatible with each other. Thanks to the positive rake angle, the milling cutter works much smoother than its predecessor.

Small Mill Great Achievement

The High Feed End Mill is primarily used to rough small and medium-sized components and celebrate the addition. New cutting materials for machining stainless steel and superalloys enable efficient and reliable machining of other application areas.

Best Tool for All Applications

All indexable inserts are the same size, regardless of the diameter of the cutter body. This reduces both investment and storage costs. The excellent combination of hard metal and coating guarantees high process reliability and long service life, which can be used for all applications.


A high-feed mill is an excellent choice for long reaches because the bulk of cutting forces is sent via the spindle. The method excels in rigid materials ranging from tool steels to aerospace alloys.

Here are five applications that High Feed End Mills excel in:

  1. A High Feed End Mill is perfectly designed for roughing, deep pocketing, face milling, slotting, and 3D milling. The machines incorporate smaller axial depths of cut and high radial depths of cut where HEM toolpaths show a heavy axial depth of cut and light radial depths of cut. These machines can manage a large radial depth of cut – approximately 65% to 100% of the cutter diameter with a small axial depth of cut – approximately 2.5% to 5% diameter depending on the application.
  2. The rigidity and strength of the high feed end mill make them ideal for materials that are difficult to machine. The high feed end mills are coated with a Tplus coating, providing high hardness and long life in high-temperature alloys and iron materials up to 45Rc.
  3. These high feed end mill designs and short cut lengths work in conjunction with shank geometry to further limit deflection and provide tools with a powerful core that allows for longer reach tools. This tool reduces radial cutting forces.
  4. The end profile of this tool is designed so that the cutting force is directed up the tool axis to the spindle. This reduces radial cutting resistance that causes deflection, increases tool reach, and reduces chatter and other problems that can lead to tool failure.
  5. Cycle Time For applications with high RDOC and low ADOC, these tools can be pushed much faster than traditional end mills, saving time and money over the tool’s life.


The high feed end mills are designed for face milling machines, roughing machines, slot milling machines, deep pocket milling machines, and 3D milling machines. These tools use chip thinning and a small axial depth of cut to enable significantly higher feed rates with a special final shape. Combining the final shape and short cut length provides a tool that works well on very hard and tough-to-machine materials.

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Vincent Hua
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