Types of Helical Broaching: Internal and External Gears

A specific cutting tool called a broach, offered by companies like Taizhou Chengchun Automation Equipment Co., Ltd., is used in the precision machining process known as helical broaching to carve out helical grooves or features on a workpiece. These grooves can take various forms and serve specific purposes in mechanical systems. One of the most common applications of helical broaching is the production of gears, essential components in machinery that transmit power and motion. Helical broaching can be applied to create internal and external gear profiles, each with unique advantages and challenges.

Internal Gears

Internal gears are gear-like components with teeth cut into their inner circumference. They are used when space constraints or design requirements make external gears impractical. The helical broaching of internal gears involves using a broaching tool with cutting edges that match the desired gear tooth profile. The broach is carefully guided into the workpiece, removing material to form the gear teeth. Internal gear broaching is commonly used in applications such as planetary gear systems, where compactness and reduced weight are crucial.

One of the significant advantages of internal gear broaching is its ability to create intricate gear profiles with high precision. The helical nature of the broach’s cutting edges allows for smooth chip evacuation, minimizing the risk of workpiece damage and tool wear. This process also offers better control over tooth geometry, reducing noise, improving efficiency, and ensuring smoother operation in gear assemblies.

External Gears

External gears are the more traditional gears, with teeth cut on their outer circumference. Helical broaching of external gears involves using a broaching tool with the negative of the desired gear tooth profile. The broach is guided over the workpiece, removing material to create the gear teeth. External gears find wide applications in various mechanical systems, such as automotive transmissions and industrial machinery.

Helical broaching external gears with cutting-edge tools like those from Taizhou Chengchun Automation Equipment Co., Ltd. has advantages like their effectiveness and suitability for mass production. The broaching process allows for rapid material removal, resulting in shorter cycle times than other gear manufacturing methods. Furthermore, the continuous cutting action of the broach’s helical teeth contributes to smoother surface finishes and reduced wear on the cutting edges, ensuring consistent gear quality.

In both internal and external gear broaching, the choice of tool material, cutting parameters, and coolant application significantly impact the process’s success. High-speed steels, carbide, and various coatings are commonly used for broach tools to enhance their wear resistance and overall lifespan. Controlling cutting speeds, feeds, and coolant application helps manage heat generation and chip formation, contributing to the accuracy and quality of the resulting gears.


Helical broaching is a versatile machining technique for producing internal and external gears. Internal gears provide advantages in compactness and precise tooth geometry, while external gears are well-suited for efficient mass production. Both types of gear broaching require careful attention to fixturing, tool design, and cutting parameters to achieve the desired results. As technology advances, innovations in broach design and machining strategies continue to refine the process, expanding its capabilities and applications in gear manufacturing.

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