CNC Knowledge: Solutions for the treatment of deformation of thin wall parts

Solutions for the Treatment of Deformation of Thin Wall Parts: A Comprehensive Guide

Deformation of thin wall parts is a common problem in various industries, particularly in aerospace, automotive, and medical devices. Thin wall parts, such as those with complex geometries and precise dimensional requirements, are prone to deformation during treatment, which can compromise their functionality and lifespan. In this article, we will delve into the causes of deformation, analyze the problems associated with handling these parts, and provide solutions to mitigate deformation and ensure precision.

Characteristics of Thin Wall Parts

Thin wall parts, such as short hollow trees (Figure 1) and solver seats (Figure 2), often possess unique characteristics that make them challenging to process. These parts typically have high precision requirements, with dimensional precision in the range of IT5 ~ IT7, coaxiality of φ0.008 ~ φ0.015 mm, and verticality of 0.010 ~ 0.015 mm. Their wall thickness is typically thin and prone to distortion, making them susceptible to deformation during processing.

Challenges in Treatment and Measurement

The processing of thin wall parts is a complex process that requires accurate planning and execution. The treatment process typically includes rough machining, semi-finishing, and finishing, with each stage critical to the overall outcome. Measurement and inspection are also essential to verify the accuracy of the parts. However, the deformation of these parts can compromise their dimensional precision and shape, making it challenging to meet the required tolerances.

Causes of Deformation

Deformation of thin wall parts can be attributed to several factors, including:

1. Redistribution of internal stress during processing.
2. Inadequate positioning surface that does not meet the required standards, leading to rebound deformation.
3. Inconsistent tightening that can cause deformation due to stress points.
4. Machining forces that can alter the part’s shape during processing.
5. Cutting heat that can cause residual stress and deformation.
6. Unreasonable part design that can predispose the part to deformation.

Solutions for Deformation Control

To mitigate deformation and ensure precision, several strategies can be employed:

1. Controlling stress relief through heat treatment, including rough processing, semi-finishing, and finishing.
2. Improving positioning surface accuracy by using grinding, grinding, or other finishing methods.
3. Modifying compression to control deformation, such as radial compression or axial compression.
4. Reducing cutting forces by using finishing techniques like grinding or polishing.
5. Minimizing cutting heat by using cutting fluids or reducing cutting speeds.
6. Improving part design by adding support ribs or symmetrical design to reduce deformation.

Case Studies: Processing Thin Wall Parts

To illustrate the effectiveness of these solutions, we present two case studies:

Case Study 1: Processing Short Hollow Trees

For short hollow trees, a key challenge lies in maintaining the part’s coaxiality and roundness. To address this, we employed the following measures:

1. Crowning the reference surface to ensure accurate positioning.
2. Designing special tools (Figure 3) with an axial tightening method (Figure 4).
3. Reducing finishing allowance from 1 mm to 0.5 mm.
4. Ensuring a stress-relieved surface by using a thermal stress relieving treatment.

These measures resulted in a roundness of 0.01 mm, coaxiality of φ0.006 ~ φ0.015 mm, and a success rate of 100%.

Case Study 2: Processing Solver Seats

For solver seats, the unique characteristics of the part design and wall thickness require special consideration. To address this, we employed the following measures:

1. Aging the part to release internal stress.
2. Using a radial tightening method (Figure 5) to control deformation.
3. Reducing finishing allowance from 1 mm to 0.5 mm.
4. Ensuring precision positioning, ensuring dimensional tolerance and position requirements.

These measures resulted in a roundness and coaxiality that met the requirements, with a success rate increase from 15% to 90%.

Conclusion

Thin wall parts pose significant processing challenges, but by understanding the causes of deformation, analyzing the problems associated with handling these parts, and implementing effective solutions, manufacturers can ensure precision and accuracy. By crowning the reference surface, designing special tools, reducing finishing allowance, and ensuring stress relief, manufacturers can achieve high-quality products with reduced deformation. By controlling handling, processing, and finishing, manufacturers can confidently deliver high-precision products that meet the required tolerances.