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Rapid development in the modern manufacturing industry has led to significant progress. Consequently, thin-walled parts are now commonly used in aviation, automobiles, and high-precision equipment.
Due to their lightweight, strength, and energy efficiency, these parts have gained popularity. Nonetheless, their unique structure poses numerous technical challenges in CNC machining.
These difficulties require scientists and engineers to develop scientific and effective strategies to optimize and solve them.
Brief Introduction of CNC Machining Technology for Thin-walled Parts
Thin-walled parts are common in mechanical manufacturing, electronic engineering, and other industrial fields. These parts have relatively small wall thicknesses compared to other dimensions.
The main goal of this design is to reduce weight, save materials, improve efficiency, or meet specific design requirements
1. Characteristics analysis
Thin-walled parts have unique structural characteristics that present multiple challenges during machining.
First, they have low rigidity, and their physical properties make them prone to deformation under any form of external pressure.
In addition, friction and heat during machining can also affect the parts, causing thermal deformation. This thermal deformation not only affects the size and shape of the parts but may also affect their physical properties.
Finally, due to their weak structure, these parts are prone to unnecessary vibrations during cutting, which can seriously affect the accuracy and effectiveness of machining.
2. Choose the right tool
The choice of tool is particularly important for CNC machining of thin-walled parts.
Due to the unique structure of such parts, you must select tools with the right tip radius and cutting angle.
This ensures that the force generated during cutting is evenly distributed. It also reduces the pressure on the parts.
In addition, the use of specially designed tools can effectively reduce the generation of friction and heat, thereby reducing the risk of thermal deformation.
3. Processing strategy
For thin-walled parts, it is necessary to process them in stages, such as rough machining to remove most of the excess material, and then semi-finishing and finishing.
This step-by-step processing method can effectively reduce the pressure on the parts and ensure their stability during the processing.
You need to carefully select and adjust cutting parameters, such as cutting speed, feed rate, and cutting depth. This ensures the stability and efficiency of processing.
Process quality issues in CNC machining of thin-walled parts
1. Easy to deform during processing
The unique structure of thin-walled parts makes them extremely sensitive to external stress.
Even small external pressure can cause deformation. During CNC machining, cutting force and clamping force combine. This combination makes the deformation more obvious.
Heat accumulation causes thermal expansion. Material removal releases internal stress. Both factors are the main causes of deformation.
This deformation can result in inaccurate dimensions, shape deviations, and even damage to the workpiece.
2. Rough surface easily causes scratches
The surface roughness of thin-walled parts directly affects the performance, life, and assembly accuracy of the parts.
During the machining process, due to the inherent low rigidity and easy vibration of thin-walled parts, unstable cutting may occur even under the best cutting conditions.
This instability leads to high-frequency vibration, which in turn causes periodic rough textures or scratches on the workpiece surface.
3. Easy to be damaged during processing
The risk of damage is relatively high during the processing of thin-walled parts. This is closely related to their weak structure.
Excessive cutting force or uneven force distribution may cause damage or breakage of parts. In addition, the clamping method also plays a key role.
Excessive clamping force or improper clamping method may cause deformation or damage to parts.
4. Size and shape are prone to deviation
Machining thin-walled parts face technical challenges in meeting the required accuracy and shape. Machine tools are the core of CNC machining.
The imbalance of the spindle, the slight offset of the slide, and the wear of other mechanical parts may cause part size deviations.
During the machining process, continuous friction and pressure subject the tool to wear. As the tool wears, the cutting effect gradually decreases.
This decrease affects the size and shape of the workpiece. Worn tools cause dimensional deviations. They may also deteriorate the surface quality of the workpiece or leave tool marks.
Improvement strategy for the quality of CNC machining of thin-walled parts
To solve the problems of thin-walled parts being easily deformed, scratched, and damaged, we can adopt simulation technology.
We can also optimize workpiece clamping methods and set cutting angles scientifically. Using the best tool path form and optimizing the process flow will help improve the results.
1. Use simulation technology
With the rapid development of science and technology, simulation technology is becoming more and more mature and widely used.
Using simulation technology, we can simulate the CNC machining of thin-walled parts. This allows us to predict the cutting force, vibration, and thermal deformation problems that may occur during machining.
As a result, we can optimize cutting parameters, tool selection, and machining paths. This method improves machining quality and efficiency.
It also reduces errors in the actual machining process. This leads to savings in both time and cost.
2. Optimize the workpiece clamping method
Here is the revised version with active voice and simplified sentence structure:
When machining thin-walled parts, you must choose the right clamping method. Technologies like internal positioning fixtures or magnetic chuck adsorption can improve machining quality significantly.
In actual operation, you need to design the best support and clamping force based on the workpiece’s special strength.
Thin-walled parts have low rigidity, so you must provide proper support during clamping. This support enhances the workpiece’s processing strength.
It also prevents damage to the workpiece from excessive clamping force. Therefore, when clamping these parts, carefully evaluate and adjust the clamping force. This ensures the parts do not deform during processing.
For workpieces with greater rigidity, you need to increase the clamping force to achieve a better clamping effect.
When selecting a fixture, consider the process requirements and material properties of the thin-walled parts. Ensure the selected fixture can meet the processing needs effectively.
3. Scientifically set the cutting angle
The cutting angle directly affects the processing quality of thin-walled parts. If you set the cutting angle improperly, it will reduce the processing quality of the parts.
The accuracy may not meet the requirements. This will affect subsequent applications. Therefore, it is crucial to choose a reasonable cutting angle when processing thin-walled parts.
First, if the workpiece has a hole, set the cutting angle slightly smaller. Make sure the angle does not exceed 5°.
This will effectively prevent the tool from vibrating excessively when it contacts the workpiece. As a result, it will reduce errors during the machining process.
Second, when processing the surface contour of the part, use a tangential or arc-shaped feed method.
This feed method reduces unnecessary textures on the surface of the part. It also improves the surface quality.
During the cutting process, you should determine the best main and secondary rake angles. Set the main rake angle between 93° and 97°.
Keep the secondary rake angle between 8° and 12°. This will reduce tool wear and ensure both tool life and cutting effectiveness during processing.
By setting the cutting angle and feed method reasonably, you can significantly improve the processing quality and precision of thin-walled parts.
This ensures their stability and reliability in practical applications.
4. Use the best cutting pattern
When machining thin-walled parts, turning plays a key role in the research. To ensure part quality and precision, set the optimal tool path.
Calculate the cutting amount based on the material and product size. This helps determine the tool movement and material feed rate.
4.1Calculating Cutting Parameters
After calculating the cutting amount, set the spindle speed, back-cutting depth, and feed amount accordingly.
For aluminum alloy materials, refer to Table 1 and Table 2 for specific values.
You can adjust these values based on the material, processing needs, and tool type.
Table 1: External Turning Back Cutting Depth Selection Table
Table 2: Aluminum Material Cutting Parameters
4.2Designing the Cutting Pattern
When designing the cutting pattern, determine the optimal tool path. Consider the following three points:
（1）Roughing Process
For roughing, use a better step-roughing method instead of traditional tool paths. This ensures stable movement of the workpiece in both horizontal and vertical directions.
Remove excess material according to the part shape and specifications. This improves cutting quality.
（2）Symmetrical Machining
Symmetrical machining usually produces better results. As shown in Fig. 2, this approach prevents deformation during cutting. It is often the preferred tool path.
Fig 2 Symmetrical machining of tool paths
（3）Feed Type and Surface Quality
Different feed types affect surface quality. Adjusting the feed type removes tool marks and improves the surface finish of parts. This is demonstrated in Figs. 3 and 4.
Fig 3 Effect picture with knife marks
Fig 4 Effect without knife marks
5. Optimize process flow
First, we must strengthen the structural analysis of parts. We should accurately identify the characteristics of the parts. We need to detect any potential deformation problems.
Then, we can apply relevant technologies and theories to design a set of processing technologies that suit the parts. Next, we will use experimental analysis to verify the process’s effect.
We should identify any shortcomings and deficiencies. Afterward, we can optimize the process to improve it.
When processing thin-walled parts, we should use special pressure monitoring instruments. These instruments will monitor the stress conditions of the parts.
We need to continuously adjust the processing orientation of the parts. This will help the tool make better contact with the parts.
It will also prevent violent vibrations during processing. This approach ensures that the quality of the parts meets the required standards.
6. Introducing adaptive processing technology
Adaptive machining technology is an intelligent machining method. It relies on real-time monitoring and feedback.
When machining thin-walled parts, the forces between the tool and the workpiece change as the process progresses.
Sensors and control systems monitor the cutting force, temperature, and vibration. The system then adjusts cutting parameters, such as feed rate and spindle speed, dynamically.
This real-time adjustment reduces errors in machining. It also lowers the risk of material deformation during the process. This helps ensure stable and consistent machining quality.
Adaptive technology is particularly useful when machining complex structures and high-precision parts. It can greatly improve both efficiency and precision.
7. Use vibration-damping devices and smart tool holders
Thin-walled parts are susceptible to vibration during machining, which can lead to reduced machining accuracy and poor surface quality.
To this end, vibration reduction devices can be used or smart tool holders with active control functions can be used.
These tool holders have built-in sensors and control systems that can detect vibrations in real time and suppress them by adjusting the internal damping structure.
In addition, vibration-reducing supports can be used or passive vibration-reducing materials can be installed during machining to further improve machining stability.
This can reduce friction and vibration between the tool and the workpiece, ensuring the final machining effect.
8. Apply advanced material coating tools
To improve the performance and life of the tool, manufacturers can use tools with advanced coatings, such as nanocoatings and diamond coatings.
These coatings reduce friction and heat. They also improve the wear resistance of the tool. As a result, the quality of the machined surface improves.
When processing high-strength alloys or composite materials, coated tools reduce the impact of cutting heat.
They also reduce the frequency of tool wear. This improves production efficiency.
In addition, using the right tool coatings makes the processing smoother. It also reduces the risk of tool marks on the surface of the part.
9. Environmental control and constant temperature processing
When processing thin-walled parts, temperature fluctuations cause thermal expansion in both the workpiece and the machine tool.
This expansion affects processing accuracy. To ensure dimensional stability, you can control the temperature in the processing environment.
By introducing a constant temperature system in the workshop, you can stabilize the temperature around the machine tool and the workpiece. This helps reduce errors caused by thermal deformation.
For temperature-sensitive tasks, you can use coolant along with the constant temperature process. This prevents sudden temperature rises during processing.
This strategy improves processing accuracy, reduces the scrap rate, and enhances product quality.
10. Composite processing technology
Composite machining combines multiple machining methods, such as turning, milling, and laser-assisted machining.
This process can complete several tasks at once. It reduces the number of times parts transfer between machine tools. It also minimizes positioning errors.
When machining thin-walled parts, laser-assisted machining heats the material locally. This reduces the material’s hardness. It also lowers cutting forces and reduces deformation risks.
Additionally, composite machining shortens processing time. It improves production efficiency and ensures the overall quality and consistency of parts.
Conclusion
The technical challenges in CNC machining of thin-walled parts restrict its widespread application.
Adopting a series of improvement strategies can solve these challenges.
These strategies include using simulation technology, optimizing workpiece clamping methods, and scientifically setting cutting angles.
Additionally, adopting the best tool path form and optimizing the process flow can efficiently improve the quality of CNC machining for thin-walled parts.
