Are humanoid robots the same as industrial robots for parts processing?

Many engineers and purchasers who have just started working on humanoid robot projects will ask: Is the machining of humanoid robot parts the same as that of industrial robots? In fact, they are completely different, whether it is the joint structure, driving form, material selection, or the difficulty of part processing, the two have fundamental differences. Next, we will compare and analyze the processing differences between the two from six dimensions.

1、 Joint structure: from single axis transmission to multi degree of freedom linkage

The joints of industrial robots often use single axis rotation, taking the mainstream six axis robotic arm as an example: one joint corresponds to one degree of freedom. The standard module of motor, reducer, and encoder is integrated, and the housing is designed around a transmission chain. Usually, only 2-3 surfaces need to be machined, and the position and tolerance belong to the common category of CNC machining.

The joint design concept of humanoid robots is completely different: the hip joint needs to achieve three degrees of freedom simultaneously, including flexion, extension, adduction, abduction, and rotation, while the ankle joint requires two degrees of freedom. Multiple transmission chains need to be arranged in a very small housing, with extremely compact spatial relationships between each other. For the machining of humanoid robot parts, this type of shell generally needs to process more than 5 faces, and any deviation of the reference on one face will affect the motion accuracy of the entire chain, requiring a five axis linkage clamping to meet the requirements. Moreover, for the purpose of biomimicry and functional integration, humanoid robot shells extensively use irregular surfaces and deep cavity structures, resulting in poor tool accessibility. The difficulty of programming and collision verification far exceeds the regular appearance of industrial robots.

2、 Different driving methods give rise to new types of parts

Industrial robots are mainly driven by low degree of freedom electric/hydraulic/pneumatic, pursuing heavy load, high speed, and absolute trajectory accuracy. The mainstream solution is motor direct drive or combined with planetary/harmonic reducers, with a short power transmission path. The corresponding parts mainly include reducer flange, output shaft, and mounting plate, with mature technology and good batch consistency, which can be produced by the vast majority of CNC factories.

Humanoid robots are mainly driven by high degree of freedom electric drives (frameless torque motors+reducers/screws). In order to pursue humanoid compliant force control and dynamic balance, a large number of tendon rope drives (i.e. wire drives) are used - the drivers are concentrated on the trunk or upper arm, and the force is transmitted to the fingers and wrists through steel wires or high-strength ropes. This architecture has given rise to a category of parts that are almost invisible on industrial robots:

Wire wheel and guide path - micro pulleys used for rope turning, the groove accuracy directly determines whether the rope is out of groove, and the consistency of the position of the multi pulley axis affects the routing accuracy of the entire tendon rope. The outer diameter of these parts is mostly between 8-20mm, with a tolerance level of around IT7, which is not extreme but requires meticulous attention to detail.

Tensioning mechanism components - precision thread fitting structure, thread diameter and clearance fit determine the response accuracy and backlash of tension control.

These parts belong to a new category in the machining of humanoid robot parts, and suppliers must understand the functional logic of line drive in order to accurately interpret the key dimensions on the drawings.

3、 Material difference - lightweight is the core constraint

Industrial robots are fixed on the ground or beams, and their own weight is not the main design constraint. The materials used are mainly 6061 aluminum alloy, 304/316 stainless steel, and alloy structural steel, with mature cutting parameters and a complete supply chain.

Humanoid robots need to be able to stand and walk quickly, and every gram of weight loss at the end directly affects their endurance and dynamic response. Material selection and industrial robots are almost two separate systems:

1、7075-T6 aluminum alloy dominates absolutely - with high specific strength, widely used in structural components such as joint shells and connecting rods. 2024-T3 is used for occasions with higher fatigue performance requirements.

2、Titanium alloy TC4 is used in end skeletons, biomimetic fingers, and other parts that are very demanding on weight. Its specific strength is equivalent to 7075 but its absolute strength is higher, and it can make thinner structures. The difficulty lies in the fact that the cutting speed is only 1/3-1/4 of that of aluminum alloy, the tool consumption is high, and without actual machining experience, problems are easily encountered. According to feedback from the Huiwen Zhizao technology team, they use specialized coated cutting tools combined with high-pressure internal cooling to control the tool breakage rate at around 3%, but the prerequisite is sufficient experience in titanium alloy processing.

3、PEEK and carbon fiber composite materials have begun to appear on joint insulation parts and weight reducing filling parts. Cutting fluid cannot be used during processing (PEEK absorbs water and degrades), and a process of air cooling, coarse and fine separation, and drying must be used.

For robot parts suppliers, the basic threshold for accepting orders for humanoid robots is whether they can handle aluminum alloy, titanium alloy, and engineering plastics at the same time.

4、 Agile Hand Skeleton - The Most Difficult Category to Process

The end tools of industrial robots (welding gun, gripper, suction cup) have a single function, a small number of parts, a simple structure, and precision concentrated on the flange installation surface.

The dexterous hand of humanoid robots is of a completely different scale - with 12-20 degrees of freedom for a single hand, the finger skeleton combines extremely small size, thin-walled structure, and multi axis hole coaxiality requirements:

1、The length of the finger joint is only 30-50mm, the width is 6-12mm, and the thinnest wall thickness is only about 1mm. Controlling cutting deformation and clamping errors at this scale requires extremely high process experience. When processing such thin-walled parts, Huiwen Zhizao uses vacuum suction cup clamping combined with coarse and fine separation technology, effectively reducing clamping deformation and cutting heat effects.

2、Each finger joint has 2-4 hinge holes (diameter 2-4mm), and the coaxiality between the holes directly determines whether the finger bends and extends smoothly. Dense machining of small holes on thin-walled structures can cause hole displacement due to clamping force and cutting heat.

3、TC4 titanium alloy with extremely small size, tool diameter as small as 0.5mm, extremely limited chip space, high risk of tool breakage. This is a widely recognized difficult to machine category in the precision machining of robot parts.

4、The joint friction surface requires low roughness (Ra0.4-0.8), and some aluminum alloy parts also need hard anodizing to improve wear resistance.

5、 A table to see the core differences clearly

6、 Control of batch consistency

The processing of industrial robot parts is usually in a "large quantity and few varieties" mode. A model of joint seat can be made into tens of thousands of pieces, and stable mass production can be achieved after the process is mastered. The focus of quality control is on the final inspection stage - after completion, it is sent to the third coordinate system and qualified for storage.

The precision machining of humanoid robots is currently in the stage of "small batch and multiple varieties": the quantity of each part is not large, but the whole machine factory has extremely high requirements for batch consistency. The assembly accuracy directly determines the motion performance, and fluctuations in the size of a joint component may lead to unstable gait of the entire machine.

This means that the quality control logic must be rebuilt: we cannot wait until everything is completed before final inspection and picking of waste products. We must conduct on machine testing or rapid sampling after each critical process, and compensate the tool immediately if any trend deviation is found. This' closed loop within the process' mode puts forward new requirements for equipment stability, measurement response speed, and process personnel experience.

summary

The difference between humanoid robot parts processing and industrial robot parts processing is far more than just accuracy, with different joint configurations, drive schemes, material selection, and part complexity. High quality suppliers need to consider processing capabilities such as multi material processing and five axis processing, which can significantly reduce the prototype iteration cycle. Like Huiwen Zhizao, which is rooted in Shenzhen and focuses on precision manufacturing of robot bodies, with a factory area of 20000 square meters and 370+equipment, it is suitable for processing multiple materials such as aluminum, titanium, and alloy steel. It is proficient in high-precision processing of humanoid robot shaped multi degree of freedom shells, from drawing review to batch delivery, and helps customers quickly iterate prototypes.

As a service provider specializing in robot parts processing, Huiwen Zhizao can provide full stage OEM services for humanoid robots, mechanical dogs, flexible robotic arms, bionic robots, medical robots and other parts from single piece sampling to medium to large-scale production. At present, Huiwen Zhizao has provided robot parts processing services to many technology innovation enterprises and research institutions such as Huawei, Xinsong, Xiaomi ecological chain enterprises, Beijing Institute of Technology, and Chinese Academy of Sciences, and its accuracy and stability have been unanimously recognized by customers.

If you need a machining plan or quotation for humanoid robot parts, please feel free to provide drawing consultation.