Causes of deformation in mechanical parts processing

In CNC machining process of parts, deformation can sometimes occur during and after the CNC machining process, particularly with thin-walled or curved surface products. These issues must be anticipated and addressed before developing the CNC machining process. Proper consideration of factors such as clamping techniques, cutting parameters, and material behavior under stress is essential to minimize deformation and ensure high-quality parts.

1. Changes in part accuracy due to internal forces

During lathe machining, the workpiece is usually clamped tightly using a three-jaw or four-jaw chuck, utilizing centripetal force to secure the part before machining begins. To ensure the workpiece remains stable under force and to reduce radial force, the clamping force must exceed the cutting force. The clamping force increases and decreases along with the cutting force to maintain stability. However, once the chuck is released after machining, the finished part can deviate significantly from its original shape, sometimes forming polygons or ovals, resulting in considerable deviations from the intended dimensions.

2. Deformation after heat treatment

Thin-walled mechanical parts are particularly prone to deformation after heat treatment due to their large aspect ratios. They may experience “hat-shaped” bending, where the middle bulges out and the flatness of the surface increases. These deformations occur not only because of internal stress changes after heat treatment but also due to a lack of specialized knowledge among operators, who may not fully understand the structural stability of the part, increasing the probability of deformation.

3. Elastic deformation caused by external forces

Several factors can lead to elastic deformation during machining:

• Thin sections in parts: Thin sections demand more precise operational methods; otherwise, poor handling during positioning and clamping can cause elastic deformation, especially if the operator doesn’t follow the part’s design.
• Uneven lathe and fixture surfaces: When the part is clamped on an uneven surface, uneven forces on both sides can lead to shifting and deformation during cutting.
• Improper positioning: Improper positioning during machining can weaken the part’s rigidity, making it more susceptible to deformation.
• Cutting force: Cutting forces can also lead to elastic deformation of the part. These different causes highlight how external forces impact the quality of machined parts.

We are a professional precision CNC machining parts manufacturer in China with extensive experience and advanced equipment to effectively control deformation in thin-walled curved parts, particularly in five-axis machining products.