Precision 6061 Hollow Bracket with Integrated Air Duct and Black Hard Anodizing

We manufactured a precision 6061 aluminum hollow bracket with an integral curved air duct for a 3C automation cooling module. The component features thin-wall hollow sections and an enclosed airflow channel requiring smooth internal surfaces — presenting two core challenges: thin-wall chatter during hollow section milling and air duct internal surface finish control. Thin-wall hollow structures are inherently rigid-deficient; conventional milling can induce harmonic vibration and chatter marks. We implemented vibration-dampening toolpath strategies — reducing radial engagement on finishing passes, tuning spindle speeds to avoid resonance, and sequencing cuts to balance material removal forces[citation:2]. For the air duct internal surfaces, we applied light finishing passes with controlled stepovers, achieving the required surface smoothness without secondary finishing. The bracket was then black hard anodized (MIL-A-8625 Type III) for wear resistance and uniform appearance.

Project Overview

Key Technical Highlights

• Thin-Wall Chatter Suppression: Followed deep-cavity thin-wall best practices — reduce radial depth of cut, increase spindle speed, and use 2-flute sharp tools with light finishing passes to minimize cutting forces. Anti-vibration toolpaths with variable stepovers prevented harmonic resonance[citation:2].
• Air Duct Surface Finish: Internal duct surfaces finished with light stepovers and controlled finishing parameters, achieving Ra≤1.6μm without the need for secondary polishing[citation:7].
• Deformation Prevention: Roughing with moderate depth, followed by stress-relief pause before finishing — allowing residual stresses to dissipate and preventing hollow structure distortion.

Quality Verification

CMM inspection verified dimensional accuracy and flatness. Air duct internal surfaces inspected for finish and cleanliness. Anodized coating verified per MIL spec.

Industry Applications

Ideal for 3C automation cooling brackets, electronic enclosures with integrated airflow, and lightweight structural housings.

Why Partner With Us?

• Proven expertise in thin-wall hollow structure machining with chatter suppression
• In-house black hard anodizing with MIL-spec compliance
• 12+ years serving 3C automation and equipment manufacturing sectors