Flat Broaching: The Complete Guide

What is Flat Broaching?

Flat broaching is a metalworking process in which material is removed from the surface of a workpiece using a flat broach to obtain a flat surface. The plane broach moves along the surface of the workpiece under the action of tension, and its teeth gradually cut off the allowance on the workpiece, thereby achieving high-precision plane processing.

Advantage of Flat Broaching

  • High processing accuracy: Plane broaching can obtain very high flatness and surface roughness, and dimensional accuracy can be controlled within a small range.
  • High production efficiency: A large amount of material can be removed by broaching at one time, which greatly improves production efficiency and is especially suitable for mass production.
  • Wide scope of application: It can process various materials, including steel, cast iron, non-ferrous metals, etc.
  • Long tool life: Flat broaches are usually made of high-strength materials and have good wear resistance. With reasonable use and maintenance, the tool life is long.

Disadvantage of Flat Broaching

  • High equipment cost: Surface broaching requires the use of specialized broaching equipment, which is expensive and occupies a large area.
  • High tool cost: The manufacturing process of flat broach is complex and requires high-precision processing equipment and technology, so the manufacturing cost of the tool is high.
  • Poor flexibility: Plane broaches are special tools that can only process planes of specific sizes and shapes. For workpieces with complex shapes or large changes in size, different broaches need to be replaced, resulting in poor flexibility.

Structure Of Flat Broach

The flat broach mainly consists of the following parts:

  • Neck: Located between the handle and the cutter body, its main function is to clamp and transport the broach during the manufacturing process.
  • Transition cone: enables the broach to enter the workpiece smoothly.
  • Leading part: guides the broach to enter the workpiece correctly and prevents the broach from deflecting when entering the workpiece.
  • Cutting part: It consists of several cutter teeth and is the main working part of the broach, used to cut off the allowance on the workpiece.
  • Calibration Department: Perform final calibration and trimming of workpieces to ensure processing size and shape accuracy.
  • Rear guide part: guides the broach to withdraw from the workpiece correctly and prevents the broach from deflecting when withdrawing from the workpiece.

Process Of Flat Broaching

1.Preparation

  • Choose a suitable flat broach and ensure that the size and accuracy of the broach meet the processing requirements.
  • Pre-process the workpiece, such as removing oil, rust and other impurities on the surface, to ensure the flatness and cleanliness of the workpiece surface.
  • Check broaching equipment to ensure its accuracy and performance meet processing requirements.

2.Install Broach And Workpiece

  • Install the broach on the broaching machine, making sure that the handle of the broach is firmly connected to the chuck of the broaching machine.
  • Install the workpiece on the table of the broaching machine and use appropriate fixtures to position and clamp it to ensure that the workpiece does not move during the broaching process.

3.Adjust Broaching Parameters

  • According to the workpiece material, size and accuracy requirements, parameters such as broaching speed, feed amount and cutting depth are adjusted.

4.Perform Broaching

  • Start the broaching machine, the broach gradually enters the workpiece under the action of pulling force, and broaching begins. During the broaching process, pay attention to the processing conditions, such as cutting force, temperature, surface quality, etc. If there are any abnormalities, stop the machine for inspection in time.

5.Clean and inspect

  • After broaching is completed, clean the chips and debris from the workpiece and broach.
  • Carry out dimensional measurement and surface quality inspection on the processed plane to ensure that the processing quality meets the requirements. If necessary, subsequent finishing or processing can be performed.

Applications Of Flat Broaching Process

  • Machinery manufacturing: In the field of machinery manufacturing, plane broaching is widely used to process the planes of various mechanical parts, such as boxes, bases, workbenches, etc.
  • Automobile manufacturing: In automobile manufacturing, plane broaching is used to process the plane surfaces of parts such as engine blocks and transmission cases.
  • Aerospace: In the aerospace field, plane broaching can be used to process high-precision flat surfaces such as aircraft engine parts and spacecraft structural parts.
  • Mold manufacturing: In mold manufacturing, plane broaching is used to process flat surfaces such as the parting surface and cavity surface of the mold.

Common Problems And Solutions In Flat Broaching

The plane broaching process may encounter some problems in practical applications. The following are common problems and solutions:

1.Rough Broaching Surface

Reason:

  • Broach wear: After a broach is used for a long time, the teeth of the broach will gradually wear, causing the cutting edge to become dull, thus making the broaching surface rough.
  • Unreasonable cutting parameters: For example, the broaching speed is too high, the feed rate is too large, etc., which will increase the cutting force and cutting heat, causing built-up edges and thorns on the surface of the workpiece, resulting in rough surface.
  • Poor cooling and lubrication: Insufficient cooling and lubrication will increase the cutting temperature, aggravate tool wear, and also affect the discharge of chips, resulting in rough surfaces.
  • The hardness of the workpiece material is too high: When the hardness of the workpiece material is too high, it is difficult for the broach to cut, and it is prone to vibration and chipping, thus making the surface rough

Solution:

  • Replace the worn broach in time: When the broach is worn to a certain extent, it should be replaced with a new one in time to ensure the sharpness of the cutting edge.
  • Adjust cutting parameters: According to the workpiece material and processing requirements, reasonably adjust parameters such as broaching speed, feed amount, and cutting depth to reduce cutting force and cutting heat, and reduce surface roughness.
  • Improve cooling and lubrication conditions: Use appropriate cooling lubricant and ensure that it is fully supplied to the cutting area to lower the cutting temperature and reduce tool wear. It also facilitates the discharge of chips and improves surface quality.
  • Pretreatment of workpieces: For workpieces with too high hardness, heat treatment such as annealing or normalizing can be performed to reduce their hardness to facilitate broaching.

2.Dimensional Deviation

Reason:

  • Inaccurate broach size: There may be dimensional errors in the broach during the manufacturing process, or the size may change due to wear and other reasons during use, resulting in dimensional deviations in the processed workpiece.
  • Inaccurate installation of the workpiece: During the installation process of the workpiece, if the positioning of the workpiece is inaccurate or the clamping force is uneven, it will cause the workpiece to be displaced or deformed during the broaching process, resulting in dimensional deviations.
  • Uneven broaching force: Uneven broaching force can cause the workpiece to bend or twist during the broaching process, resulting in dimensional deviations.

Solution

  • Check and correct the size of the broach: Before using the broach, check whether its size is accurate. If there is an error, it should be corrected or replaced in time.
  • Ensure the correct installation of the workpiece: During the installation process of the workpiece, appropriate positioning methods and clamping devices should be used to ensure accurate positioning and uniform clamping force to avoid displacement or deformation during the broaching process.
  • Optimize the broaching process: By adjusting cutting parameters, improving cooling and lubrication conditions, etc., the broaching force is reduced, the broaching force is evenly distributed, and the deformation of the workpiece is reduced.

3.The Broach Is Broken

Reason

  • Excessive broaching force: When the broaching force exceeds the strength limit of the broach, it will cause the broach to break. The reasons for excessive broaching force may be unreasonable cutting parameters, excessive hardness of the workpiece material, severe broach wear, etc.
  • There are defects in the broach: The broach may have cracks, slag inclusions and other defects during the manufacturing process. These defects will reduce the strength of the broach and easily lead to breakage during the broaching process.
  • Improper operation: such as sudden stop during broaching, collision between the broach and the workpiece, etc., may cause the broach to break.

Solution

  • Adjust cutting parameters: Reduce parameters such as broaching speed, feed, and cutting depth to reduce broaching force and avoid broach breakage.
  • Check the quality of the broach: Before using the broach, check whether its quality is up to standard. If it is defective, it should be replaced in time.
  • Standard operation: During the broaching process, the operation should be strictly followed to avoid sudden shutdown, collision between the broach and the workpiece, etc.

4.Flatness Error

Reason

  • Straightness error of the broach: The broach may have straightness errors during the manufacturing process, or the straightness may change due to wear and other reasons during use, resulting in flatness errors in the processed workpiece.
  • Non-parallel installation of the workpiece: During the installation process, if the workpiece is not parallel to the movement direction of the broach, it will cause uneven stress on the workpiece during the broaching process, resulting in flatness errors.
  • Vibration occurs during broaching: If vibration occurs during broaching, it will cause ripples on the surface of the workpiece, thus affecting the flatness.

Solution

  • Check and correct the straightness of the broach: Before using the broach, check whether the straightness is accurate. If there is an error, it should be corrected or replaced in time.
  • Ensure that the workpiece is installed parallel: During the installation process of the workpiece, appropriate positioning methods and clamping devices should be used to ensure that it is parallel to the movement direction of the broach to avoid uneven stress during the broaching process.
  • Take measures to reduce vibration: You can reduce vibration during broaching and improve flatness by adjusting cutting parameters, improving cooling and lubrication conditions, increasing the rigidity of the broach, etc.

Conclusion

As a high-precision and high-efficiency processing method, plane broaching plays an important role in the field of modern mechanical processing. By understanding the process principles, advantages and disadvantages, tool types, structures, processing steps, precautions, manufacturing processes, application fields, and common problems and solutions of plane broaching, we can better master the plane broaching process and provide practical production Strong support.

In practical applications, we should select appropriate flat broaches and processing parameters according to specific processing requirements, and strictly control all aspects of the processing process to ensure processing quality and production efficiency.

At the same time, we should also continue to explore and innovate to promote the development and progress of plane broaching technology. If you would like to know more about surface broaching, please feel free to contact us.


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