Machining Thin and Long Aluminum Cylindrical Parts Without Deformation

Product Background

The customer is a technology-driven company specializing in the development of high-precision mechanical assembly equipment. Its products are mainly used in scientific research, testing, and precision assembly applications.

This part serves as a core structural support component within the equipment and is primarily used to mount and precisely position multiple functional modules and sensor assemblies. To ensure long-term operational stability and reliability, the part requires strict control of coaxiality, roundness, and the positional relationships between multiple assembly datums.

In addition, the part is produced in multiple repeated batches, making consistency of key dimensions and geometric accuracy across different production runs equally critical.

Leveraging Wayken’s extensive experience in machining complex structural components, along with standardized manufacturing and quality control processes developed for small-batch and multi-iteration projects, we have continuously delivered stable, high-quality parts to the customer, ensuring reliable project progress and follow-up supply.

Part Structure Analysis

The part features an overall thin-walled cylindrical structure with an outer dimension of approximately 150 mm. The wall thickness is unevenly distributed, resulting in relatively low local rigidity, making it a long, thin component that is prone to deformation during machining.

Multiple holes and elongated slots are distributed on the outer circumference, while the inner side includes mounting windows and stepped features, all of which impose high requirements on coaxiality and datum consistency. During machining, the part is easily affected by cutting forces, posing challenges to fixturing methods and overall process stability.

Machining Considerations and Solutions for Thin-Walled Cylindrical Part Structure

To ensure both dimensional accuracy and structural stability, targeted process strategies were applied based on the part’s geometry and tolerance requirements.

1. Deformation Control: Stepwise Machining + Stress Relief

This batch of cylindrical housings has a length of 199 mm, features a hollow interior, and has thin walls. These structural characteristics make the part highly susceptible to warping and deformation during CNC machining, significantly increasing the difficulty of precision control.

At the same time, the part has precision assembly requirements, with a hole diameter tolerance of ±0.01 mm and coaxiality tolerance of ±0.02 mm, further increasing the machining challenge.
Based on our experience with high-precision, deformation-prone components, we developed a stepwise process route of rough machining → stress relief → finish machining.

Stepwise Machining Strategy

First, rough turning is performed, leaving a 0.05 mm machining allowance to accommodate potential deformation. This is followed by a critical stress relief stage, where the part is left at room temperature for a defined period, allowing internal residual stresses from cutting to gradually dissipate through atomic-level relaxation, stabilizing the part geometry. Finally, CNC finish machining is carried out to achieve the final dimensional requirements.

Through the combination of stepwise machining and stress release, we effectively controlled deformation risks during processing and consistently achieved high dimensional accuracy and coaxiality.

2. Machining Strategy for Low-Rigidity Stepped Features

The part includes local stepped structures with relatively large lengths and low rigidity, representing a key machining challenge. For these features, we adopted a process route of initial turning followed by CNC milling. Different machining stages introduced challenges related to chatter control and fixturing stability, which are addressed in detail below.

Suppress Chatter on Overlong Parts

For thin-walled cylindrical components, insufficient local rigidity combined with long tool overhang makes chatter likely during cutting.

To address this issue, we adopted stepwise machining and optimized cutting parameters to reduce the load per pass and improve machining stability. In addition, internal supports and customized fixtures were used to secure critical areas of the workpiece and enhance overall rigidity. These measures effectively suppressed vibration and ensured dimensional accuracy, including critical hole tolerances. The turning stage achieves the condition shown in the figure below.

Fixturing Solution for the Cylindrical Housing

Given the hollow and elongated structure of the part, customized fixtures were designed to prevent deformation during machining. On one hand, precise positioning prevents inward contraction; on the other, structural support based on the part geometry improves overall rigidity, ensuring machining stability and hole position accuracy.

3. Integrated Machining for Side Rectangular Slots and Holes

To ensure positional accuracy and consistency across multiple circumferential features, an integrated machining approach was adopted.

4-Axis Machining Strategy

The cylindrical part features various circumferential structures, including rectangular slots and holes. We utilized a 4-axis machining solution to complete all features in a single setup, efficiently ensuring accuracy across all structures.

Using a 3-axis machine would require multiple setups and machining from different orientations, making the process extremely difficult or nearly impractical. A 5-axis solution, while feasible, would be excessive and unnecessarily increase cost. The 4-axis single-setup approach offers the most balanced solution in terms of accuracy, efficiency, and cost.

Fixture Design for Hollow Structure

To accommodate the hollow structure, a custom internal expansion fixture was developed. The fixture uses tapered screw heads; when tightened, the fixture expands to firmly support the inner surface of the part, achieving a tight and uniform fit.

With this internal support, the part maintains excellent rigidity during machining, preventing deformation of the cavity under localized cutting forces. Although the stepped area itself is not directly supported by the fixture, no machining features are present in its immediate vicinity, so overall machining accuracy is not affected.

Feedback

Through stepwise machining, stress relief treatment, and customized fixturing solutions, we successfully addressed challenges related to chatter, fixturing stability, and complex feature machining on this thin-walled, elongated cylindrical component.

The final parts demonstrated stable dimensions and met all accuracy requirements. Upon receiving the parts, the customer expressed satisfaction with the machining quality, reflecting the careful process control and precision applied throughout production. WayKen ensures the customer receives reliable, high-precision CNC machined parts that support smooth assembly and consistent performance across production batches.