On November 5th, at the 2025 XPENG Tech Day,the company unveiled its next-gen humanoid robot — IRON.
The moment it walked out, it felt like a character that just stepped directly out of Westworld — lightweight posture, natural muscle lines, even its head movement and gait looked almost indistinguishable from a human. The audience couldn’t help but ask:
“Is this a real robot… or is there a person inside?”
The next day, XPENG CEO He Xiaopeng answered the question in the most direct way possible — he cut open the robot’s leg “muscle” live, while the robot was still powered on.
The blade sliced through the flexible skin — and instead of metal gears or hydraulic pipes — what appeared was a dense lattice structure — honeycomb-like, but far more orderly and engineered.IRON continued walking smoothly, and the room erupted in applause.
That single cut didn’t just end the debate of “is this real or fake?”
It opened a new conversation that forces the entire industry to rethink how humanoids should be built — structurally, mechanically, and materially.
Unlike traditional rigid, gear-centric human-shaped robots, IRON is closer to an actual biological body — natural joint compliance, continuous motion, structural flexibility. And behind this realism is one key enabler — 3D printing applied deep into bionic skeletal + muscle system generation.
The Meaning of “That Cut” This wasn't theater.
It was a historical dividing line.
Humanoid robotics has always struggled with a fundamental paradox:
either it’s human-like, or it’s machine-like.
Rigid actuators force robots into rigid motion logic.
But muscle — true muscle — requires a balance of power and compliance.
IRON’s internal lattice shows a breakthrough approach: moving from “component assembly” → “structural generation.”
Manufacturers are no longer assembling parts — they are programming structure… printing shape and capability at the same time.
EPFL research this year showed this direction clearly — a single elastic material can exhibit multiple degrees of stiffness via topology and structural programming.
IRON is the industrialization prototype of this:
simulating biology using structure, reconstructing motion through manufacturing geometry.
The Black Technology: 3D Printing Enables What Traditional Manufacturing Simply Can’t
Injection molding and CNC can’t produce gradient lattices with millions of variable-density micropatterns.Additive manufacturing can.
Among all AM processes, DLP/SLA photopolymerization is uniquely capable of printing flexible micro-lattice structures at tens-of-micron precision — which is exactly what biological muscle demands.
Smooth surfaces
Uniform stress distribution
Zero nozzle resolution limits
Programmable stiffness gradients within one single print
Elasticity + strength coexist.
That is why IRON’s internal “muscle” is printed with high-precision photopolymer elastomers — perfectly matching humanoid robot needs: continuous motion + light weight + fatigue life.
At this point the manufacturing logic completely flips:
instead of forcing biology into mechanical logic — the industry starts to build machines with biological logic.
Material Evolution: When Elastomers Become Muscle
The magic isn’t only the geometry — materials evolution makes the geometry meaningful.
Modified photopolymer resins now combine rubber-level elasticity with engineering-grade structural strength. This allows one continuous printed part to carry completely different mechanical missions inside different areas — rigid where support is required, soft and dynamic where muscle movement is needed.
Pollyfab invested 7+ years down this path — starting from polymer science → inventing their own hardware → pushing process breakthroughs — resulting in HALS ultra-speed photopolymer 3D printing, with elastomer mass production capability already proven in footwear, helmets, saddles, lumbar support, pillows and more. They’ve developed over 8,000 polymer formulations, including dental, engineering and anti-static materials — forming a flexible cross-industry AM matrix.
For humanoid robot future high load cases — they introduced multilayer structural honeycomb composite materials: high elasticity, tear resistance, extreme fatigue life — over 1,000,000 bending cycles.
Data shows:
these multi-layer structures absorb energy 4× more efficiently than traditional honeycombs — while maintaining excellent recovery under cyclic loading.
This is the foundation that turns “bionic muscle” from concept → reality.
When IRON Was Cut Open, The World Saw A Manufacturing Paradigm Shift
Industrial era machines = metal bones.
Intelligent era machines = material structure growing into muscle.
3D printing is no longer merely a prototyping tool — it becomes a structural programming language.
Geometry logic + materials science + digital light field control =
machines gaining biologically-analog adaptive physical morphology.
Conclusion
He Xiaopeng’s single cut did not just peel open a shell.
It opened the gate to a new industrial era.
From humanoids, to prosthetics, to footwear, to sports protection, to soft joints, to smart wearables — any field requiring power + flexibility coexistence will be reshaped.
Years from now, when people look back at this launch, that cut will be a symbol.
It showed the world that a robot isn’t only chips and algorithms — it also has manufacturing intelligence hidden beneath its skin.
