This is a custom 5-axis CNC machined joint motor housing for a humanoid robot, machined from 7075-T6 aluminum alloy. The part provides the structural base for mounting and enclosing the harmonic drive reducer. Its integrated design combines a precision motor cavity with a flat mounting base, eliminating the need for separate adapter plates or brackets.

7075-T6 aluminum alloy was selected for this part due to its high tensile strength, good machinability, and low density. Compared to the more common 6061 alloy, 7075-T6 offers significantly higher strength, making it well suited for structural components in humanoid robots where both load-bearing performance and weight reduction are critical requirements.

The deep bowl-shaped cavity is the primary feature of this part. It is designed to house and the harmonic drive reducer precisely. The inner wall is finish machined to achieve the required dimensional accuracy and surface quality for motor fitment. The flat rectangular base provides a stable mounting interface with the robot chassis or frame. Corner mounting holes allow secure bolted attachment to the main structure. The smooth curved transition between the mounting base and the motor cavity distributes stress evenly across the part, reducing the risk of stress concentration under load.

Part type: Custom Humanoid Robotic Joint Motor Housing

Material: 7075-T6 Aluminum Alloy

Machining Process:  5-Axis CNC Milling

Surface Finish: As-Machined

Machining Process

The part was machined from a solid 7075-T6 aluminum alloy billet using a 5-axis CNC milling center. The process followed these general steps:

1. Raw material preparation – Aluminum billet cut to approximate size
2. Roughing – Bulk material removed to establish overall form including base and cavity rough shape
3. Semi-finishing – Base surfaces and cavity walls brought close to final dimensions
4. Finishing – Final passes on all critical surfaces including cavity inner wall and base mounting face
5. Hole machining – Drilling, boring, and tapping of cavity rim threaded holes, base mounting holes, and underside boss features
6. Deburring and cleaning – All edges deburred and parts cleaned before inspection

Each part was inspected to ensure dimensional accuracy before surface treatment.

Why 5-Axis Machining

The geometry of this part makes it well suited to 5-axis CNC machining for the following reasons:

• Deep cavity machining – The bowl-shaped motor cavity requires precise tool angle control to reach all internal surfaces and achieve consistent inner wall finish.
• Curved transition surfaces – The smooth curved transition between the base and cavity requires continuous multi-axis tool movement to achieve the required surface quality.
• Multi-face hole features – Threaded holes on the cavity rim and mounting holes on the base are completed in a single setup, ensuring accurate positional relationships.
• Integrated form in a single setup – The complete part geometry is machined with minimal repositioning, reducing cumulative error and ensuring the motor cavity is accurately positioned relative to the mounting base.

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