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5 Main Types of Milling Processes

Table of Contents

Milling, a pivotal CNC machining process, harnesses the prowess of multi-edge cutters to remove material, shaping various objects with remarkable precision. Essential in manufacturing, milling processes are classified based on the directional approach of the cutting tool, including face Milling, end Milling, thread milling, angle milling, shoulder milling, and others, each offering unique capabilities and serving specific applications.

CNC machining

Overview of Types of Milling Processes

Milling stands as a cornerstone in the machining world, delivering a variety of operations that expertly carve out material from a workpiece to craft precise components.The categorization of milling is often drawn along the lines of the cutter’s positioning—horizontal and vertical milling form the foundational approaches, each adept at shaping workpieces in their unique way to fit a multitude of designs.

The milling operations mainly discussed in this article are the following:

  • Face Milling
  • End Milling
  • Thread Milling
  • Angle Milling
  • Shoulder Milling

1. Face Milling: Techniques and Applications

face milling

Face Milling stands as a central technique in modern manufacturing, renowned for its capacity to generate perfectly flat surfaces. Utilizing a cutter with its axis perpendicular to the workpiece, Face Milling swiftly shears away material, leaving behind a smooth finish. This process is crucial in industries that demand high precision, such as automotive and aerospace, where large surface areas need to be milled uniformly.

Applications of Face Milling are diverse and can be broken down into several key areas:

  1. Creating a Flat Surface:This is the most common application for Face Milling, particularly in the preparation of mating surfaces, where a flat and smooth finish is crucial.
  2. Heavy Stock Removal:Due to the cutter’s design, Face Milling is ideal for removing large amounts of material quickly, making it a first step in the machining of cast or forged parts.
  3. Finishing:With the right tooling, Face Milling can achieve very fine finishes, which makes it suitable for the final finishing pass on a part, eliminating the need for additional grinding or machining.
  4. Die and Mold Making:In die and mold making, the squareness and surface finish are critical. Face Milling is often used here to ensure that the die or mold has the proper dimensions and surface quality.
  5. Aerospace and Automotive: In these industries, Face Milling is used to create large flat surfaces on body parts and frames, where precision and strength are of paramount importance.


While the process is lauded for its excellent surface finish and rapid production capabilities, it’s important to acknowledge certain challenges as well. A notable limitation of Face Milling is the potential cost associated with tooling, particularly for specialized or small-scale tasks. Despite this, the technique remains a fundamental process for manufacturers seeking efficiency and precision in their milling operations.

2. End Milling

end milling

End Milling refers to a versatile CNC machining process where the cutting action occurs at the tip as well as the periphery of the end mill cutter. Unlike Face Milling, which primarily uses the face of the tool, End Milling involves the cutter’s end for cutting and shaping the workpiece. This process can be used to create a variety of features such as slots, pockets, and complex contours.

The applications of End Milling are wide-ranging and can be itemized as follows:

  1. Slotting: This involves creating slots of various shapes and sizes and is one of the most frequent uses of End Milling.
  2. Pocketing: End Milling is well-suited for hollowing out a section of a workpiece to create pockets or recesses.
  3. Profiling: The process is also utilized for profiling operations, where the peripheral cutting edges create the desired outer form of a part.
  4. Contouring: With the ability to navigate complex paths, End Milling can produce intricate contours and fine details in workpieces.
  5. Drilling and Plunging: While drilling is not the primary purpose, end mills can plunge into the material to create the initial cavity for other milling operations.

3. Thread Milling

thread milling

Thread Milling is defined as a machining process used to create threads within a hole or on the outside of a cylinder. It involves the use of a rotating, multi-point cutting tool, called a thread mill, to carve threads into the workpiece precisely. This process is versatile and can produce internal or external threads, straight or tapered threads, and even threads of varying diameters from the same tool.

s the thread mill moves up or down along this helical path, it creates a full thread in a single 360-degree rotation. Unlike tapping, which can create only one specific thread size, Thread Milling is more versatile because one tool can be used for various thread diameters and pitches. This process also allows for adjustment to be made for tolerances, thread fit, and to compensate for any material variations.

Types of threads that can be milled

Thread Milling is a precise and versatile process used in CNC machining to create threaded parts. It is appreciated for its accuracy and the ability to produce a wide range of thread forms which include:

  1. Internal Threads: Thread mills can produce precise and smooth internal threads, commonly used in nuts, bores, and other internal threading applications.
  2. External Threads: Similarly, thread milling can fabricate accurate external threads on bolts, shafts, and other cylindrical parts.
  3. Straight Threads: These are the standard threads used for most fastening applications with a uniform diameter throughout.
  4. Tapered Threads: Tapered threads, often seen in pipe fittings, diminish in diameter along their length and can be milled with specialized thread mills.
  5. Right-hand Threads: The most common thread direction, where the thread tightens clockwise.
  6. Left-hand Threads: These are less common and tighten counterclockwise, often used in applications where standard right-hand threads would come loose due to the direction of rotation or force.
  7. Fine and Coarse Threads: Depending on the application’s requirement for thread spacing, thread mills can produce both fine (closely spaced) and coarse (widely spaced) threads.
  8. Multi-start Threads: A multi-start thread consists of two or more intertwined threads running parallel to one another, allowing for faster thread engagement.


Please note that these are just some common thread types, and more special thread types may be involved in actual applications.For more thread information, please refer to IFI-8 Standards Assembly.


Advantages of Thread Milling over traditional threading methods


  1. Versatility: A single tool can produce various thread sizes and types, eliminating the need for multiple taps or dies.
  2. Quality and Strength: Thread milling typically results in higher quality, stronger threads with better dimensional accuracy and a smoother finish.
  3. No Breakage Risk: Unlike taps, thread mills don’t run the risk of being broken inside the part, as they are less prone to snapping due to their design and the way the force is distributed during machining.
  4. Adjustability: It’s easier to adjust the thread fit for different tolerances, enabling more precise control over the thread’s final dimensions.
  5. Burr-Free: The milling process usually produces clean, burr-free threads, reducing the need for secondary finishing operations.
  6. Threading to the Bottom: Thread mills can produce threads close to the bottom of a blind hole, whereas taps require a specific amount of clearance at the bottom.
  7. Improved Tool Life: Thread mills have a longer tool life than taps, as the cutting load is distributed across multiple teeth and they can be re-sharpened or have their cutting edges replaced.
  8. Better for Difficult Materials: Thread milling is often preferred for hard or brittle materials, as the cutting process is less aggressive than tapping, reducing the chance of material damage.

4 . Angle Milling

angle milling

Angle Milling is a highly precise CNC machining procedure used to create beveled edges and specific angled features on parts. Essential for components requiring slanted surfaces or angular cuts, such as gears and brackets, this process excels in crafting chamfers and complex angular profiles.

It is particularly valued in the aerospace and automotive industries for its ability to generate aerodynamic shapes and parts that need to fit together at precise angles. Angle Milling is known for its high precision, which is crucial for intricate designs and superior craftsmanship.

This milling technique stands out by minimizing manual interventions and potential errors associated with complex angular machining. The use of advanced CNC technology ensures accelerated production times without compromising the exactitude of the cuts. Embracing Angle Milling allows for a meticulous finish and unmatched detail in the final product.

5 . Shoulder Milling

shoulder milling

Shoulder Milling is a critical technique in types of milling, creating precise right-angled edges on parts essential for assembly. Widely used in sectors like automotive and aerospace, it’s integral for shaping features such as gear slots with CNC machining for high precision and repeatability.

This process excels in versatility, handling various materials to produce complex profiles needed for components with stringent engineering demands. Shoulder Milling remains a key operation in manufacturing, ensuring sharp, clean edges for high-quality product finishes.

Comparison of different types of milling processes

Each milling process has its unique attributes that make it more suitable for specific manufacturing scenarios.

Feature End Milling Face Milling Thread Milling Angle Milling Shoulder Milling
Cutting Action Tip and periphery Face of the cutter Helical cutting edge Cutter positioned at an angle Periphery cutting with a square shoulder finish
Applications Slots, pockets, complex contours, and fine details Flat surfaces, high-quality finishes, heavy stock Precise threads, internal and external Chamfers, bevels, tapered features Step features, square-edged slots, and fine edges
Material Removal Moderate to high High Low to moderate, depending on thread size Moderate Moderate to high
Finish Varies from rough to fine, depending on the tool Typically very fine and smooth Clean, precise threads Clean angular cuts, usually requires finishing Precise, straight edges with a good surface finish
Flexibility Highly versatile for various shapes Limited to planar surfaces Specialized for threads only Limited to angled features Good for 90-degree edges and complex profiles
Set Up Complex due to multi-directional cutting Simpler setup as mostly planar cutting Specialized setup for threads Requires precise angle setup Complex due to the need for precise edge alignment


As we’ve explored throughout this article, the world of milling is both vast and intricate, encompassing a wide range of types of milling processes, each with its specific set of applications and advantages. From the traditional Face Milling and End Milling to the precision of Thread Milling and the versatility of Shoulder Milling, these techniques form the backbone of modern manufacturing, shaping the way we create parts across various industries.

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