How Does A Rotary Broach Work

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Introduction to Rotary Broaching

A rotary broach is a specialized cutting tool used in machining processes to create precision shapes and forms in workpieces. It is commonly used in industries such as automotive, aerospace, and medical, where intricate shapes or internal features need to be machined accurately.

Working Principle

The working principle of a rotary broach involves a rotating tool known as a broaching tool. The broaching tool has a series of cutting edges arranged in a specific pattern that corresponds to the desired shape to be machined. As the broach rotates, the cutting edges engage with the workpiece, removing material gradually, creating the desired shape.

Broaching Process

The process of rotary broaching typically involves several steps:

  1. Workpiece Setup: The workpiece is securely positioned in the rotary broaching machine or lathe.
  2. Tool Alignment: The broaching tool is aligned with the workpiece, ensuring proper engagement.
  3. Tool Engagement: The broaching tool is gradually fed into the workpiece, allowing the cutting edges to remove material.
  4. Rotational Motion: The broaching tool rotates continuously, creating the desired shape in the workpiece.
  5. Axial Feed: Simultaneously, the broaching tool moves axially into the workpiece, which facilitates the cutting process.
  6. Coolant and Lubrication: Coolants or lubricants may be used to reduce heat and friction during the broaching process.
  7. Finishing and Inspection: After broaching, the workpiece is typically inspected for dimensional accuracy and surface finish.

Types of Rotary Broaches

There are various types of rotary broaches available, each suitable for specific applications:

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  • Internal Rotary Broach: Used to create internal shapes or splines inside a workpiece.
  • External Rotary Broach: Designed for machining external shapes or spline profiles on the outer surface of a workpiece.
  • Polygon Rotary Broach: Ideal for creating polygonal shapes or forms, such as squares, hexagons, or octagons.

Advantages of Rotary Broaching

Rotary broaching offers several advantages:

  • Precision and Accuracy: Rotary broaching allows for high precision and accurate machining of complex shapes.
  • Time Efficiency: It enables fast machining due to its continuous cutting action.
  • Surface Finish: Rotary broaching produces excellent surface finish, reducing the need for secondary finishing operations.
  • Cost-Effective: It eliminates the need for multiple tool setups and reduces overall manufacturing costs.

Tips for Successful Rotary Broaching

To ensure optimal results when using a rotary broach, consider the following tips:

  • Select the appropriate broaching tool based on your desired shape and material being machined.
  • Maintain tool sharpness by regularly inspecting and resharpening the cutting edges.
  • Optimize cutting parameters, including rotational speed, feed rate, and depth of cut.
  • Use appropriate coolants or lubricants to improve cutting performance and prolong tool life.


Rotary broaching is a versatile machining process that allows for precise shaping and forming of complex features in workpieces. By understanding its working principle, process, and advantages, manufacturers can harness the power of rotary broaching to enhance their machining capabilities and achieve high-quality results.


Q: How long does it take to rotary broach a part?

A: The time it takes to rotary broach a part depends on several factors, including the complexity of the shape, the material being machined, and the cutting parameters. However, rotary broaching is generally known for its time efficiency compared to other machining methods.

Q: Can I rotary broach both internal and external shapes?

A: Yes, rotary broaching is capable of machining both internal and external shapes. Internal rotary broaches are used for creating internal features, while external rotary broaches are used for machining external profiles.

Q: Is rotary broaching suitable for all materials?

A: Rotary broaching can be used on a wide range of materials, including metals, plastics, and even some hard materials. However, the specific parameters, such as cutting speed and tool material, may need to be adjusted based on the material being machined.

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