Manufacturability Analysis of CNC Machining for Complex Aluminum Alloy Cavity Parts

In CNC machining, the manufacturability of complex parts directly impacts production efficiency, cost, and product quality. Today, Elite Mold Tech will use a typical aluminum alloy complex cavity part as an example to share practical solutions for CNC machining design for manufacturability, covering structural design, tolerance specifications, dimensional measurement, and quality assurance. Leveraging our professional technical team and extensive machining experience, we provide end-to-end services from design to post-processing, helping customers overcome machining challenges and achieve efficient production.

I. Basic Information of the Case Part

As shown in the figure below, the part analyzed is a large cavity part with dimensions of 328×272×87.5mm, made of AL6061. From a structural and functional perspective, this part is cleverly designed:

In terms of production methods, this part utilizes differentiated strategies based on the production stage:

II. Structural Design Analysis: Optimization Directions for CNC Machining

Since this part uses die-casting + CNC machining for mass production, designers initially prioritized structures compatible with die-casting. However, during early engineering verification and small-batch production (when full CNC machining is used), some structural features conflicted with CNC requirements, requiring targeted optimization.

(I) Clearance Issues Between Threaded Posts and Heat Sinks

The threaded posts on Side B extend to Side A, with a designed gap of several millimeters between the posts and the heat sink—creating numerous narrow, deep structures. Fully machining these areas would require custom, extra-long, small-diameter tools. However:

After consulting with designers, we used conventional extended small-diameter tools for corner cleaning (no further machining). As shown in the figure, the posts and heat sinks on Side A are not fully connected—this ensures basic part functionality while avoiding machining risks.

(II) Gap Problems Caused by Post Depth

The threaded posts in the Side B cavity have a large depth, creating gaps with adjacent surfaces and forming narrow spaces. This issue shares the same root cause as the above: tool limitations lead to discrepancies between actual machining results and the 3D model.

Recommendation for future designs: Fully consider CNC tool compatibility, and reasonably control post depth and gap sizes with adjacent surfaces.

(III) Proper Design of Cavity Internal Angles and Draft Angles

The Side B cavity has numerous internal corner radii (R). For die-casting, small R values in deep cavities can be achieved with draft angles. However, for CNC machining:

Key guideline: We recommend controlling the ratio of maximum R to depth within 10:1. For this part, the ratio reached ~40:1 at its deepest point—far exceeding the reasonable range—so we had to increase the R value during machining.

If extreme ratio designs are required (due to product functionality):

(IV) Impact of Groove Radius Design on Machining Efficiency

Some grooves in the cavity have radii at the notch or bottom. For die-casting, this design adds no difficulty, but for CNC machining:

Cost & efficiency note: Machining time is a core factor in CNC cost accounting. Regular structures (no radii) can use 2D toolpaths, which are far more efficient than 3D toolpaths.

After consulting with designers, we adjusted these radiused structures to regular shapes—this significantly improved machining efficiency and reduced costs without affecting part functionality.

III. Tolerance Specification Definition: Balancing Quality and Economy

For new part categories (without mature reference products), designers often over-specify tolerance controls. For this part:

While 2D dimension/tolerance inspection is essential for machined parts, over-control increases inspection workload and production costs. To address this:

This adjustment ensures core performance and assembly accuracy while streamlining production/inspection processes and reducing overall costs.

IV. Dimensional Measurement and Quality Assurance: Precisely Controlling Product Quality

After simplifying the number of inspected dimensions, we established a comprehensive quality assurance system to control quality from pre- to post-machining.

(I) Developing Detailed Inspection Specifications

We created a clear inspection operation table, defining:

This avoids errors from inconsistent inspection processes and ensures accurate, consistent results.

(II) Flexible Selection of Professional Measuring Tools

For small-batch parts, Coordinate Measuring Machines (CMM) are the primary tool. CMMs offer comprehensive measurement capabilities, making them ideal for parts with small quantities and multiple dimensions.

(III) Double Quality Verification (Pre- & Post-Machining)

Stage	Verification Method
Pre-machining	Use professional CAM software for detailed simulations: Check machining paths for over-cutting or missing structures (avoids errors at the source).
Post-machining	1. Compare physical products with 3D models (verify structural integrity). 2. Spot-check reference dimensions (confirm dimensional accuracy).

V. Case Summary: Professional Solutions for Cost-Quality Win-Win

The cavity part in this case has:

Facing these challenges, Elite Mold Tech:

The result: We met the customer’s quality requirements while reducing production costs—achieving a win-win for cost-effectiveness and quality.

Contact Elite Mold Tech

If you have CNC rapid prototyping needs (complex part machining or end-to-end solutions from design to post-processing), please reach out:

We look forward to working with you to overcome machining challenges and create high-quality products!