Why must the core components of humanoid robots be processed using five axis linkage?

Humanoid robots are moving from prototypes to mass production. Industry data shows that the domestic production will be about 20000 units in 2025, and there will be a significant increase in shipments in 2026.

But the real bottleneck in production capacity and yield is often not algorithms, but the dozens of joints, linkages, and dexterous hand skeletons on the robot body. These types of components have distorted shape and space, and the tolerances are extremely tight, making it difficult for ordinary three-axis machining to be completed in one go.

Firstly, the conclusion is that simple components such as end caps and casings are sufficient with three or four axes; And core components such as joints, gearbox housings, and dexterous hands basically rely on five axis linkage to simultaneously achieve angle, coaxiality, and consistency. This is also the reason why the demand for five axes has significantly increased in the past two years.

1、 The parts are not blocks, they are all spatial surfaces and oblique holes

Joint shells, dexterous finger joints, transmission links, and other components are commonly found in free-form surfaces, inclined holes, irregular deep cavities, and negative angle structures, where the holes and surfaces are not in the same direction. Three axis machine tools can only move vertically up and down. When encountering side and inclined surfaces, the workpiece must be disassembled, flipped over, and realigned. The more complex the workpiece, the more times it needs to be flipped over.

Five axis linkage machining has two more rotation axes than three-axis machining, and the tool can follow the curved surface while cutting. Complex surfaces can be continuously machined in one clamping. When making such parts, less flipping means less cumulative error, which is the most intuitive advantage of five axis compared to three-axis.

2、 The accuracy is measured by "silk" or even micrometer card

Robots must move smoothly, without jamming or abnormal noise, and the coordination between joints and transmission components must be very accurate. The repeated positioning accuracy of joint components is usually controlled at the level of 0.01mm, with stricter requirements for some coaxial and fitting features; The components of the dexterous hand are small and thin, with slightly loose tolerances, which can cause assembly to become stuck or loose.

This kind of accuracy cannot be suppressed by multiple clamping attempts - every time it is re clamped, the benchmark may deviate slightly, and the errors will be stacked layer by layer. Robot five axis machining combines multiple processes into one positioning, and with the help of online measuring heads and a constant temperature machining environment, the size can be stabilized. The precision machining area of Shenzhen Huiwen Intelligent Manufacturing has a turning capacity of ± 0.005mm and milling capacity of ± 0.01mm. It uses five axis linkage machining and turning milling composite to undertake high-precision humanoid robot components, and the key dimensions are rechecked with three coordinates.

3、 Once clamping, eliminate the error from the source

The typical process of making complex parts with three axes is: machining one side → disassembling → changing the angle and clamping → machining the other side, which involves multiple alignments and sets of fixtures. The more clamping times, the more accumulated errors and waiting times are introduced, and thin-walled parts are also prone to stress deformation due to repeated clamping.

The idea of five axes is to complete multi-faceted and porous machining in one clamping, with design, process, and measurement benchmarks as unified as possible, avoiding the pit of "repeated alignment" from the root. For core components that need to be delivered in bulk, this "one-time positioning to complete all features" approach is both a precision and efficiency measure.

4、 The knife can be straightened, and with a short knife, the deep cavity and thin wall are cleaner

The five axis also has a often overlooked benefit: it can automatically swing the blade axis to the most suitable angle. When processing the side wall of a deep cavity, the three-axis can only be avoided with a long knife. Once the knife is long, its rigidity is poor and it is prone to vibration, leaving vibration marks and tool contact marks; The five axis can deflect the cutting head in, cutting with a shorter blade, with good rigidity, making the blade smaller, and significantly cleaner surface quality.

This is particularly crucial for delicate finger joints with thin-walled hollows - these parts can deform and become useless with a single shock or pressure. Robot five axis machining can control the vibration and deformation of thin-walled parts by optimizing the tool posture and path, and predicting interference through simulation.

5、 From making one piece to making ten thousand pieces, it relies on stable replication

During the prototype stage, one can gradually repair and manually assemble it; To truly enter mass production, what is needed is thousands of sets with consistent dimensions and interchangeability. The five axis system relies on numerical control programs and stable replication through a single clamping process. After the first piece is confirmed, the consistency between subsequent pieces is high, making it more suitable for transitioning from small-scale trial production to large-scale delivery. Huiwen Zhizao has a production area of approximately 20000 square meters, with more than 370 processing and testing equipment, over 80 testing equipment, and more than 200 measuring tools. It has complete coordinate systems from Zeiss, Hexagon, and Sirui, and has passed IATF16949 and ISO9001 system certification. In addition to five axis linkage processing, it can also provide DFM manufacturability evaluation, first piece full-size testing, and small batch to batch climbing support. Customers who make humanoid robot parts usually review the process and tolerances together at the drawing stage.

6、 Not all items require five axes, don't spend money unnecessarily

'Must use five axes' is not absolute. Simple end caps, flanges, and flat shells can fully handle three or four axes, while hard five axis designs waste machine time and cost. What truly cannot bypass the five axes are core components such as joints, reducers, dexterous hands, and lightweight skeletons that require both spatial angles and micrometer level coordination.

When selecting, it is recommended to first give the drawings to a manufacturer with experience in robot five axis machining for a DFM: which features require five axis machining, which can be pre machined with three axes, and then refined with five axes. By distinguishing them clearly, a balance can be achieved between accuracy and cost.

There are specific drawings and working conditions requirements for such parts, and two-dimensional drawings, 3D models, and technical requirements can be provided. Huiwen Zhizao will conduct manufacturability evaluation and itemized quotation, and use the five axes on the key features that are truly needed.