Robot Joint Processing Technology Selection Guide: Detailed Explanation of Shoulder and Wrist Joints

Misconception in selection: Can shoulder and wrist joints really be processed in the same way?

In robot joint processing, there is a common misconception: many R&D teams and processing factories believe that the shoulder joint and wrist joint are both upper limb moving parts and can be processed using the same set of processing techniques, without the need for additional process differentiation.

The actual delivery results are often unsatisfactory - the shoulder joint has deformed and the movement gap has increased after using it for more than half a year; The hole position deviation during wrist joint assembly requires manual repair, which delays the overall assembly progress of the machine. We found that when processing orders for joint parts of such robots, choosing the wrong process may seem to save upfront preparation costs, but in reality, it actually increases rework and after-sales costs.

Unified process vs. differentiated process: which is more cost-effective?

There are two main selection ideas for robot upper limb joint processing in the industry. We compare them from three dimensions: qualification rate, long-term stability, and comprehensive cost:

1. Judging by production batch size

Small batch prototype development (1-5 samples), highly cost sensitive, can be simplified appropriately: only stress relief treatment is applied to the shoulder joint, and ordinary clamping is used to process the wrist joint to meet testing requirements, without the need for customized fixtures.

Batch production (more than 10 units) must choose differentiated processes. The cost savings brought by one-time qualification far exceed the investment in customized tooling, and stable quality can also reduce after-sales maintenance.

2. Determine based on load parameters

Industrial robots with a load of more than 10kg have higher torque borne by the shoulder joints, requiring high structural strength and deformation resistance. Therefore, differentiated processes must be selected, and a separate stress relief process after rough machining must be arranged.

For lightweight collaborative robots with a load of less than 5kg, the shoulder joint size can be simplified appropriately, but the wrist joint still needs to choose a differentiated one-time clamping scheme to ensure the accuracy of the hole system position due to the need to integrate multiple transmission parts.

3. Judging based on the design lifespan

For mass-produced models with a design lifespan of more than 5 years, differentiated processes must be selected to control internal stress and positional tolerances from the processing stage.

The prototype samples for short-term testing can be simplified to meet short-term requirements and control the cost during the research and development phase.

Robot shoulder joint processing vs wrist joint processing: completely different selection points

Key points for selecting robot shoulder joint processing

The core requirements for shoulder joint are deformation resistance and high structural strength, and the selection of process should focus on three points:

Clamping scheme: Prioritize multi-point positioning auxiliary support clamping, without using ordinary pliers, to avoid deformation caused by uneven clamping force;

Process arrangement: The stress relief process after rough machining must be arranged, and the blank should not be directly processed into the finished product;

Cutting strategy: Choose layered and uniform milling, do not remove large margins at once, and avoid stress concentration.

Key points for robot wrist joint processing selection

The core requirements for wrist joint are hole accuracy and coaxiality, and the key points for process selection are threefold:

Clamping scheme: Priority should be given to customizing zero point fixtures for one-time clamping, without multiple clamping attempts, to avoid repeated positioning errors

Hole processing method: spiral interpolation is preferred for one-time molding, without multiple hole expansions, to ensure the roughness and coaxiality of the hole wall

Heat treatment arrangement: Only stress is applied before precision machining, and multiple heat treatments are not performed to avoid deformation of small-sized parts

The above selection points need to be adjusted according to the specific joint structure design in practical operation. When we process robot joint parts at Huiwen, we intervene from the drawing review stage - many selection issues are actually buried in the design stage, such as uneven wall thickness, lack of reserved clamping positions, and unreasonable tolerance allocation.

Differentiated craftsmanship has fallen to the ground, and if quality control cannot keep up, it is useless

No matter which process scheme is chosen, sound quality control is the guarantee for implementation. We at Huiwen have developed corresponding testing standards for different selection schemes when processing robot joints: simplifying the process of prototype parts, only conducting critical dimension testing, controlling testing costs, and delivering quickly; Batch parts with differentiated processes, with a focus on checking the form and position tolerances and deformation of the shoulder joint, and checking the position and coaxiality of the wrist joint hole system. Full size inspection is completed using a coordinate measuring instrument to ensure that each piece meets the design requirements.

As a high-end robot full industry chain service provider specializing in the field of robotics in Shenzhen, Huiwen Zhizao relies on the technical background of the Chinese Academy of Sciences and has been recognized as a specialized and innovative enterprise and a national high-tech enterprise. It has passed ISO9001 and IATF16949 quality management system certification and has more than 200 processing equipment. In the field of robot joint processing, it has the full chain capability from joint structure design, precision manufacturing to component assembly. It can flexibly adjust the process plan according to customers' batch, load, and life requirements. At present, we have established cooperation with technology innovation enterprises and research institutions such as Huawei, Xinsong, Xiaomi Ecological Chain Enterprise, Beijing Institute of Technology, and Chinese Academy of Sciences, and have accumulated rich experience in process selection in the field of robot joint processing in Shenzhen.

Huiwen Zhizao provides hardware design and manufacturing services for robot bodies, covering the entire process of design (mechanical structure/electrical scheme design/process optimization), manufacturing (CNC machining/mold/surface treatment), assembly (component trial assembly/product assembly and debugging), and supporting customers to choose single or multiple service modules as needed.

For robot intelligent manufacturing services, in addition to humanoid robots, we can provide comprehensive OEM services for mechanical dogs, flexible robotic arms, bionic robots, medical robots, and more.

Especially for humanoid robots, Huiwen Intelligent Manufacturing innovatively 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.

Robot joint processing selection: differentiation is necessary for large loads, and simplification is possible for small batches

The core of selecting robot joint processing technology is not the more complex the better, but to match actual needs and distinguish the different requirements of shoulder joints and wrist joints:

1、Batch production, high load, long-life models → Differential processing technology must be selected

2、Small batch prototypes, small loads, short-term testing → optional simplified process control cost

3、Regardless of the selection, the accuracy requirements for the wrist joint hole position must be prioritized

Whether it is large-scale production, small-scale production, or sampling, Huiwen Zhizao can provide customized process selection solutions according to customer needs. If you have robot joint processing needs, please feel free to provide drawing consultation, and we will provide professional selection suggestions and quotations.