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Understanding Broaching: Definition and Overview

Broaching is a machining process that involves removing material using a special tool called a broach. The broach is a multi-toothed cutting tool that progressively increases in size, enabling it to cut different parts of a workpiece in a single pass. This process is especially efficient for producing internal keyways, splines, and other complex shapes with high precision.

Basic Components of Broaching

  1. Broach: The central component of the broaching process, the broach is a long, slender tool with multiple teeth. It is designed to progressively cut the desired shape into the workpiece.
  2. Workpiece: The material that undergoes the broaching process. It can be made of various metals, including steel, aluminum, or brass.
  3. Broaching Machine: The machinery responsible for executing the broaching process. The broaching machine holds the workpiece securely and facilitates the movement of the broach through the material.
  4. Fixture: A device used to secure the workpiece in place during the broaching operation. Fixtures ensure stability and precision during the cutting process.
  5. Cutting Fluid: To reduce friction, dissipate heat, and improve the overall efficiency of the process, cutting fluid is often applied during broaching.

Broaching Process Steps

1. Setup and Fixturing

Before the actual broaching operation, careful setup is crucial. The workpiece is securely fixed in place using a fixture on the broaching machine. Proper alignment is essential to ensure accuracy in the final product.

2. Broach Selection

Choosing the right broach is a critical decision. Broaches come in various shapes and sizes, and selecting the appropriate one depends on the desired features and the material of the workpiece.

3. Broaching Operation

The broach is carefully guided through the workpiece, cutting away material with each pass. The process is often completed in a single stroke, making it highly efficient. The cutting action can be either linear or rotary, depending on the type of broaching machine and broach used.

4. Inspection

After the broaching process, the workpiece undergoes a thorough inspection to ensure that the desired specifications and tolerances have been met. Any necessary adjustments can be made at this stage.

Types of Broaching

Linear Broaching

In linear broaching, the broach moves linearly along the workpiece. This is a common method for cutting keyways and splines. Linear broaching can be classified into two main types:

Internal Broaching

Internal broaching focuses on creating precise internal features within a workpiece. Internal broaching is highly efficient, providing exceptional precision and accuracy in producing internal features, essential for various industries like automotive, aerospace, and machinery manufacturing. The internal broach method significantly reduces the need for multiple machining operations, offering a streamlined and cost-effective solution for creating complex internal geometries with tight tolerances.

External Broaching

Unlike internal broaching, which focuses on internal features, external broaching involves cutting material from the external surface of a workpiece using a specialized broach tool. This process allows for the creation of flats, contours, or other external profiles with high precision in a single pass.

The broach, equipped with cutting edges or teeth, is carefully guided along the external surface of the workpiece, gradually removing material to form the desired shape. External broaching is highly efficient and ideal for applications requiring accurately machined external features, contributing to improved component functionality and fit in industries such as automotive, aerospace, and general engineering.

Rotary Broaching

Rotary broaching is a specialized machining process that involves the simultaneous rotation of both the cutting tool and the workpiece. Unlike traditional linear broaching, where the broach moves linearly through the workpiece, rotary broaching imparts a rotary motion to both the broach and the workpiece. This process allows for the efficient creation of intricate shapes and forms with a single pass of the broach.

The key component in rotary broaching is the rotary broach tool, which typically has a polygonal or contoured shape. The tool is designed to produce specific shapes, such as hexagons, squares, or other polygons, and it can also be customized for more complex forms like gears or splines. Rotary broaching offers several advantages including single-pass operation, improved tool life, and overall versatility.

Surface Broaching

Surface broaching is employed to cut flat surfaces on a workpiece. It is commonly used in applications where a smooth and precise finish is essential.

Pull Broaching

Pull broaching involves applying force to the broach tool in the opposite direction of the cut, drawing the broach through the workpiece. This method is more common and widely used in vertical broaching machines. Pull broaches typically have a hydraulic or mechanical system that pulls the broach downward or vertically through the workpiece that is fixed on a sturdy fixture or work table.

Push Broaching

Push broaching, on the other hand, applies force in the same direction as the cutting motion. This method pushes the broach upward or forward through the workpiece. Push broaches are less common and often used in specialized applications. They apply force from the bottom of the workpiece to push the broach upwards.

Keyway Broaching

Keyway broaching is specifically designed for cutting keyways, which are slots that accommodate keys or other mating components.

Advantages of Broaching

High Precision

Broaching is renowned for its ability to produce highly accurate and intricate shapes with tight tolerances. The single-pass operation minimizes the chance of cumulative errors, resulting in superior precision.


The efficiency of broaching lies in its ability to complete complex operations in a single pass. This reduces machining time, enhances productivity, and lowers production costs.


Broaching is a versatile process suitable for a wide range of materials, including metals, plastics, and composites. It can be applied to various industries, such as automotive, aerospace, and manufacturing.

Surface Finish

The broaching process often yields a superior surface finish, reducing the need for additional finishing operations. This is particularly beneficial in applications where a smooth surface is critical.

Broaching Applications

Automotive Industry

Broaching is extensively used in the automotive industry for manufacturing components like gears, shafts, axles, and spline shafts. The precision and efficiency of broaching make it ideal for producing the intricate shapes required in automotive engineering.

Aerospace Industry

In the aerospace industry, where precision and reliability are paramount, broaching is employed to create components such as turbine blades, engine parts, and aerospace gears.

Medical Equipment Manufacturing

Broaching is utilized in the production of medical instruments and implants, where the need for precision is critical. The process ensures the creation of intricate components with tight tolerances.

Firearms Manufacturing

In the production of firearms, broaching is commonly used to create features like rifling in gun barrels. The precision of the broaching process is crucial for the accuracy and performance of firearms.

Challenges and Considerations

Tool Wear

The cutting teeth of the broach can experience wear over time, affecting the quality of the cuts. Regular maintenance and monitoring are necessary to address tool wear and ensure consistent performance.

Initial Setup Costs

While broaching offers long-term cost savings through its efficiency, the initial setup costs, including the purchase of broaching machines and tools, can be relatively high.

Limited to Internal Shapes

While highly effective for internal machining, broaching is not suitable for cutting external shapes. Other machining processes may be required for such applications.

Future Trends in Broaching

Advanced Materials

As industries continue to explore and implement advanced materials, the broaching process is likely to evolve to accommodate these changes. New tool materials and coatings may be developed to enhance the efficiency of broaching on exotic materials.


The integration of automation and robotics into manufacturing processes is a growing trend. Broaching machines may become more automated, leading to increased precision and reduced labor costs. The CNC machining process can be used for broaching thanks to new automation technology.

Simulation and Modeling

Advancements in simulation and modeling technologies may allow manufacturers to optimize the broaching process digitally, reducing the need for physical prototypes and minimizing errors.

Broaching Machines

Broaching machines are specialized tools used to perform the broaching process, which involves cutting precise shapes or features into workpieces. There are several types of broaching machines, each designed for specific applications and varying in their mechanism of operation:

Vertical Broaching Machines

There are two types of vertical broaching machines:

Horizontal Broaching Machines

There are two types of horizontal broaching machines:

Rotary Broaching Machines

Specialized Broaching Machines

Continuous Broaching Machines

Combination Broaching Machines

Each type of broaching machine has its advantages and is suitable for specific applications based on factors such as the size and shape of the workpiece, required tolerances, production volume, and the complexity of the machining operation. The choice of broaching machine depends on the specific requirements of the manufacturing process and the desired outcome.

Broaching Materials

The materials used in broaching depend on both the broach tool and the workpiece being machined. Broach tools, being cutting tools, are typically made from hard and wear-resistant materials to withstand the forces involved in the cutting process.

The workpiece material, on the other hand, can vary widely depending on the industry and application. Here are common materials used in broaching:

Steel Alloys: Broaching is commonly used on various steel alloys, including carbon steel, alloy steel, and tool steel. These materials are prevalent in industries such as automotive and aerospace.

Aluminum: Aluminum and its alloys are often broached, particularly in applications where lightweight components are essential, such as aerospace and automotive.

Brass and Bronze: These materials are used in applications where corrosion resistance and electrical conductivity are important, such as in electronic components.

Stainless Steel: Stainless steel is known for its corrosion resistance and is commonly broached, especially in applications where hygiene and durability are critical, such as medical equipment.

Cast Iron: Broaching is also applicable to cast iron, which is used in various industries for its excellent castability and machinability.

Broaching Machine Tools

Broaches or broaching tools come in various shapes and types, each designed for specific applications and cutting requirements. Below are some common broaching tool shapes and types although custom broaches are widely used in the manufacturing industry.

Keyway Broaches:

Square Broaches:

Hexagonal Broaches:

Round Broaches:

Splined Broaches:

Dovetail Broaches:

Internal Broaches:

External Broaches:

Surface Broaches:

Involute Gear Broaches:

Serration Broaches:

Taper Broaches:

Oval Broaches:

These are just a few examples, and the diversity of broach shapes reflects the broad range of applications and machining needs in various industries. The choice of a particular broach type depends on factors such as the desired feature, material of the workpiece, and specific manufacturing requirements.

Broach Sharpening and Maintenance

Sharpening broaches is crucial for maintaining the effectiveness, accuracy, and longevity of these cutting tools. Here are key reasons why sharpening broaches is important:

Precision and Accuracy

A sharp broach ensures precise cutting teeth and accurate formation of the intended shapes or features on the workpiece. Dull or worn broach teeth may lead to inaccuracies, poor surface finishes, or deviations from the required dimensions, compromising the quality of the machined components.

Extended Tool Life

Regular sharpening removes wear and damage from the cutting edges of broaches, extending their lifespan. Proper maintenance through sharpening helps prevent premature tool failure and ensures consistent performance over multiple uses.

Efficient Cutting

Sharp broaches reduce cutting forces and heat generated during machining, enhancing cutting efficiency. This efficiency not only improves the speed of the machining process but also minimizes the risk of workpiece damage due to excessive heat or force.

Consistency in Machining

A consistently sharp broach results in consistent and uniform machined surfaces and dimensions. This is critical for maintaining tight tolerances and meeting specifications across batches of machined components.

Cost Savings

Regularly sharpened broaches contribute to cost savings by reducing the frequency of tool replacement. By maximizing the lifespan of broaches through sharpening, companies can reduce tooling expenses in the long run.

Safety Considerations

Dull or improperly sharpened broaches can pose safety hazards due to increased cutting forces, potential workpiece slippage, and erratic machining behavior. Keeping broaches sharp helps maintain a safer working environment.

Overall, the sharpening of broaches is a fundamental aspect of their maintenance and contributes significantly to the quality, efficiency, and safety of the broaching process in metalworking industries.


The broaching manufacturing process stands as a testament to the ingenuity and precision achievable in modern metalworking. Its versatility, efficiency, and ability to produce intricate shapes make it a valuable asset in various industries, from automotive to aerospace.

Start a Broaching Manufacturing Project Today

The Federal Group USA stands as the unparalleled choice for broaching solutions due to our unwavering commitment to excellence, cutting-edge technology, and a proven track record of delivering precision in metal cutting. Our company sets itself apart by investing in state-of-the-art broaching machinery and employing highly skilled professionals with extensive expertise in the field.

We prioritize customer satisfaction by offering tailor-made broaching services that meet the unique requirements of diverse industries, from automotive to aerospace. The Federal Group USA excels in delivering high-precision components with tight tolerances, ensuring that our clients receive top-notch quality products.

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