Processing of humanoid robot parts, choosing the wrong aluminum alloy grade is equivalent to doing it for nothing

What are the differences between robot parts and ordinary parts in CNC aluminum alloy processing?

CNC aluminum alloy processing covers a wide range of industries, including consumer electronics, medical equipment, and automotive parts. The CNC processing industry in Shenzhen is particularly concentrated. But there is an essential difference in robot parts processing - within the same product, the material requirements for different parts vary greatly.

A humanoid robot, with a torso that can support the weight of the entire machine, joint shells that need to be equipped with reducers and transmit force, nimble finger tips that are less than 10mm in size but have to withstand concentrated stress during grasping, and exterior coverings that have been anodized to look good. All of these are made of one type of aluminum alloy, which either wastes performance or cannot withstand it at all.

So when making robot parts, the first thing is not to choose equipment or process, but to select the right brand. Choosing the wrong one, even if processed, it won't be useful.

Four types of aluminum alloys with four characters positioning: strength, stability, visibility, and compensation

Three simple sentences to remember: 7075 is the choice of "strength", 6061 is the choice of "stability", 6063 is the choice of "observation", and 7050 is to fill in 7075's shortcomings in specific scenarios. These four are the most commonly used combinations of grades in precision machining of aluminum alloys.

Robot joint processing: Heavy duty joints must use 7075

The hip joint, knee joint, and shoulder joint, the three major joints of humanoid robots, bear loads and move more frequently than other parts. A reducer needs to be installed inside the joint shell, with limited wall thickness but force transmission, requiring the highest material strength and fatigue life.

7075-T6 is almost the only choice for making such heavy-duty joint parts. The tensile strength of 6061 is only about half of 7075, and the safety margin is insufficient in the thin-walled and hollow structure.

Processing precautions: 7075 has high hardness and tool wear is faster than 6061. During processing, it is necessary to control cutting parameters to avoid dimensional deviations. The installation reference surface and sealing surface of the joint shell are recommended to be completed in one clamping by five axis CNC machining to reduce the accumulation of errors caused by multiple clamping.

Robot body processing: skeleton uses 7075, shell depends on the situation

The robot body consists of two main types of components: the main skeleton (trunk/spine) and the thoracic shell.

The main skeleton is the load-bearing structure of the whole machine, which can withstand bending moments and impacts. 7075-T6 is the preferred choice. If the skeleton design requires welding and splicing structures, 6082-T6 can be considered as an alternative, with better welding performance than 7075.

The thoracic shell is a typical thin-walled component, with a wall thickness of 2-3mm at the thinnest point, positioning holes distributed on all four sides, and weight reducing grooves in the inner cavity. The difficulty in machining these types of parts lies not in the material, but in deformation control - after machining, if the size drifts and the hole position deviation exceeds the tolerance, manual repair is required during assembly.

The key to deformation control lies in the process sequence: after rough machining, stress must be removed before precision machining, and thin-walled surfaces and hole positions should be machined with five axis CNC machining in one clamping to avoid positional deviation caused by disassembly in the middle.

Processing of limb components: load-bearing section 7075, light load section 6061

The arm tube and calf tube belong to the category of limb members, with thin walls but large lengths, requiring high material strength (strength/density ratio).

Heavy load segment - such as calf tube, which bears the weight and impact force of the whole body when walking, choose 7075-T6.

Light load segment - such as the forearm and middle of the upper arm, with relatively low load, 6061-T6 strength is sufficient, better processing stability, and lower cost.

On the same rod, if the design allows, different materials can also be selected in sections, with 7075 for load-bearing parts and 6061 for connecting parts, assembled through bolts or crimping. This controls costs while ensuring performance.

Appearance coating: 6063 anodized with the best texture

Exterior components such as joint shells and covers do not participate in force transmission, and the core demand is a good-looking surface. 6063-T5 is the preferred choice for precision machining of aluminum alloy appearance parts.

6063 has a higher silicon content than 6061, and after anodizing, the surface is more uniform and delicate, with less color difference. The finished product texture is significantly better than 6061 and 7075. For products such as humanoid robots that require appearance, the oxidation quality of the joint shell directly affects the overall appearance.

If there is a slight load-bearing requirement for the cover (such as the need for buckle fixation), 6061-T6 is also acceptable. Although the oxidation effect is not as good as 6063, its strength is more guaranteed.

Transmission cavity processing: Whole piece CNC sampling, batch consideration of cast aluminum

The joint housing is the most typical transmission cavity component - the internal cavity accommodates the reducer and motor, with thin walls but installation reference surfaces and sealing requirements, and a complex internal cavity structure.

Sampling and small batch production (up to 50 pieces): Directly process 6061 or 7075 whole CNC aluminum alloy without the need for mold making, with high flexibility. The shell of the heavy-duty joint (hip, knee) itself participates in force transmission, using 7075; 6061 can be used for lightly loaded areas such as wrist joints.

Batch production (over 100 pieces): For complex inner cavity shells, A356 cast aluminum blanks can be considered, which are formed near net before precision machining. Cast aluminum blanks save a lot of rough machining time and material waste, and the overall cost can be reduced by about 30%. But it requires early investment in mold making, suitable for stable models with large quantities.

Huiwen Intelligent Manufacturing supports sampling, small batch, and medium to large batch robot CNC aluminum alloy processing needs, and has the ability to provide integrated design, intelligent manufacturing, and assembly services throughout the entire chain, enabling one-stop completion of the entire process from research and development to batch delivery.

Flexible hand parts processing: 7075 is a must-have

The dexterous hand is the most difficult part in the machining of humanoid robot parts - the finger joint parts are less than 10mm, the wall thickness is 2-3mm, and there is a hollow structure with complex irregular surfaces.

Under this extreme cross-section, the material strength is not 'sufficient', but 'no margin'. The tensile strength of 7075-T6 is about 560MPa, while 6061 only has about 310MPa. With the same thin-walled section, the safety margin of 6061 is far from sufficient. The smaller the part and the thinner the wall, the higher the requirement for material strength, because there is no extra cross-sectional area to cover the bottom.

The processing of dexterous hand parts involves a competition between deformation and accuracy at every step: five axis CNC machining ensures surface formation with one clamping, rough machining is followed by two stress relief processes to control deformation, and each piece undergoes full-size inspection to confirm qualification. In mass production, the impact of tool wear on dimensions is more sensitive than that of ordinary parts, requiring frequent tool changes and inspections.

Summary of Selection: One Picture Done

From sampling to batch production, Huiwen Intelligent Manufacturing independently completes the entire process of robot parts

As a robot body hardware design and manufacturing service provider rooted in Shenzhen, Huiwen Zhizao focuses on robot CNC aluminum alloy processing. Currently, the factory covers an area of 20000 square meters and has more than 370 processing equipment, including multiple five axis CNC machining centers, covering mainstream aluminum alloy grades such as 7075, 6061, 6063, 7050, etc. From robot joint processing, body processing to dexterous hand part processing, it can be independently completed.

In terms of robots, Huiwen Intelligent Manufacturing Innovation currently adopts a combination process of "new materials+new molds+precision machining", relying on integrated design, intelligent manufacturing, and assembly full chain services to complete the entire process from research and development to batch delivery in one stop, with a stable batch delivery qualification rate of over 98%.

In addition, Huiwen Zhizao can provide comprehensive OEM services for mechanical dogs, flexible robotic arms, bionic robots, medical robots, etc., which can meet diversified needs from sampling to mass production.

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