When machining a 6.2mm x 105mm slot on a thin-walled aluminum tube with a wall thickness of 1.3mm, deformation occurred, leading to inconsistent groove widths along its length. The issue was resolved through a specific machining strategy on a mill-turn machine, which successfully produced stable and accurate grooves. Here’s an analysis of why this method worked effectively:
1、Roughing Minimizes Stress Accumulation
Using a 5.7mm end mill for full-length roughing: The roughing stage left extra material along the slot, which reduced the cutting force and heat generated compared to machining the final 6.2mm width in a single pass. This approach minimized initial deformation.
2、Segmented Machining Controls Deformation
Processing in sections: The operator machined specific portions of the slot in sequence:
- At the 10mm mark, a precise 6.2mm section was machined.
- At the 26mm mark, the slot width was milled to 5.95mm.
- These steps ensured that stress concentrations were distributed across the length, preventing cumulative deformation.
Gradual expansion from rough to finished dimensions ensured that unmachined portions provided structural support to the tube, limiting wall deflection during machining.
3、Incremental Cuts for Final Precision
Tapered finishing cuts: After initial roughing and partial finishing, the operator used taper milling, gradually widening the slot from 6.05mm to the final 6.2mm width. This incremental cutting minimized sudden stress changes and ensured uniform dimensional accuracy.
4、Symmetrical Machining Balances Residual Stress
Final taper cut from the opposite end: A symmetrical machining pass connected the grooves, balancing residual stress and ensuring consistent width along the entire slot.
5、Reducing Heat and Vibration Effects
Thin-walled structures are sensitive to heat-induced deformation and vibrations. Segmented machining and gradual cutting ensured that heat generation and vibrations were minimized, resulting in stable machining conditions and improved dimensional control.
Conclusion
The success of this machining strategy lies in breaking the process into stages, distributing stress across the length of the slot, and gradually achieving the final dimensions. This demonstrates that in thin-walled machining, careful planning of machining paths, stress balancing, and controlled incremental cuts are essential to prevent deformation and produce high-quality results.
This experience underscores the importance of process optimization in thin-walled CNC machining and provides valuable insights for achieving stable dimensions in similar projects.
