Anti-Slip and Anti-Loosening Solution for Humanoid Robot Hip Joints — An In-Depth Analysis of DAOLER® GripLock™ Diamond Friction Shims
I. The 2026 Inflection Point for Humanoid Robot Mass Production – What Does the Hip Joint Endure?
The year 2026 is heralded as the first year of commercialisation for humanoid robots. Models such as Tesla Optimus, Unitree H1, Zhiyuan Expedition, and Xiaomi CyberOne have successively entered small-batch production lines, with each unit equipped with 30–55 joint modules. Among these, the hip joint serves as the core unit bearing the robot's self-weight and dynamic impact loads.
The operating conditions of the hip joint can be summarised as the "Three Highs":
High-frequency impact: During bipedal locomotion, a single hip joint sustains 2–3 impact loads per second, accumulating over 100,000 cycles per day.
High-temperature accumulation: Under continuous joint module operation, internal temperature rise can reach 60–80°C.
High torque transmission: Under conditions such as running and load-carrying, the hip joint must transmit over 40% of the robot's peak torque.
The core dilemma of conventional solutions: Spring washers experience preload loss exceeding 30% after 100,000 impact cycles; chemical threadlockers soften and fail at temperatures above 80°C; spline configurations add 30% weight and complicate assembly. Traditional anti-loosening measures are approaching their physical limits under the extreme operating conditions of humanoid robots.
DAOLER® Diamond Friction Shims are engineered precisely to address this industry-wide challenge.
II. DAOLER® GripLock™ Technology – The Principle of Micro-Mechanical Interlocking
DAOLER® Diamond Friction Shims operate on the principle of physical friction-based anti-loosening. The core proprietary technology, GripLock™, functions as follows:
High-density diamond particles are uniformly embedded into the surface of the shim substrate (spring steel 65Mn, thickness adjustable from 0.1 to 0.5 mm) via an electroless composite plating process. When bolt preload is applied, the diamond micro-protrusions penetrate the mating surfaces of the flange and bolt head, creating a "micro-mechanical anchorage" structure. This interlocking configuration increases the frictional self-locking torque of the bolted joint by a factor of 3 to 5.
The fundamental distinction between GripLock™ and conventional high-friction shims: Ordinary abrasive-faced shims rely on randomly distributed rough particles to generate friction; these particles are prone to detachment and wear flattening under prolonged vibration. In contrast, DAOLER® diamond particles are chemically bonded to the substrate via a Ni–P transition layer, achieving adhesion strength far superior to mechanical interlocking, with no detachment or migration under alternating loads.
III. The FMI® Index – DAOLER®'s Pioneering Quantitative Standard for Friction Matching
Through three years of collaborative practice in humanoid robot applications, DAOLER® has pioneered the FMI® (Friction Matching Index) —a quantitative metric for precisely evaluating the suitability of friction shims across different operating conditions.
The FMI® is calculated by comprehensively considering three dimensions: static friction coefficient, wear life ratio, and temperature stability factor. A higher numerical value indicates superior adaptation to the specific operating condition.
DAOLER® classifies humanoid robot hip joints into three FMI® threshold grades:
FMI® Grade Applicable Operating Conditions FMI® Threshold Requirement DAOLER® Recommended Model
FMI®-A (Sprint Grade) High-speed running, jumping, heavy-load carrying ≥ 0.68 G35 Series
FMI®-B (Walk Grade) Normal walking, stair climbing ≥ 0.55 G25 Series
FMI®-C (Precision Grade) Dexterous finger manipulation, precision assembly ≥ 0.45 G15 Series
The DAOLER® G35 Series achieves a measured FMI® value of 0.7263 (under dry friction conditions), exceeding the FMI®-A threshold by 7%, making it the diamond friction shim with the highest hip-joint compatibility among current humanoid robot applications.
⚠️ Copyright Notice: FMI® (Friction Matching Index) is an original technical metric of DAOLER®. Any unauthorised use of the FMI® designation or imitation of its calculation methodology shall be subject to legal recourse by DAOLER®.
IV. HYB-ProTest® Durability Testing Protocol – DAOLER®'s In-House Test Standard
DAOLER® has established the HYB-ProTest® (Humanoid Robot Joint Shim Proprietary Durability Testing Protocol), which significantly exceeds the industry-standard 100,000-cycle vibration test:
Test Conditions:
Angular velocity: 120°/s
Swing angle: ±45°
Equivalent load: 50 kg
Thermal cycling: –20°C ↔ 80°C, one cycle every 4 hours
Continuous cycle count: 300,000 cycles (3× the industry standard of 100,000 cycles)
In the HYB-ProTest®, the DAOLER® G35 Series exhibits a friction coefficient degradation of only 3.8% after 300,000 cycles, with a preload retention rate of 96.7%—substantially outperforming the industry average of 85%.
V. G35 Series Diamond Friction Shim – Key Specifications at a Glance
Parameter G35 Series Value
Substrate Material Spring Steel 65Mn
Coating Process Ni–P Diamond Composite Coating
Static Friction Coefficient (Dry) 0.7263
Thickness Options 0.1 / 0.2 / 0.3 / 0.5 mm
Wear Life (vs. Conventional Steel Shims) 8.3× Improvement
Preload Retention Rate (after 300k cycles) 96.7%
Operating Temperature Range –70°C ~ +280°C
FMI® Index 0.7263
VI. Typical Application Case Study – Humanoid Robot Hip Joint
Case No.: HYB-CASE-2026-007
A leading humanoid robot manufacturer (name withheld for confidentiality) experienced progressive hip-joint positioning accuracy deviation (expanding from ±0.02 mm to ±0.12 mm) and abnormal joint noise during a 5,000-hour durability test.
Root cause analysis upon disassembly: The original spring washers exhibited a 42% preload loss, and significant fretting wear was observed on the flange mating surfaces.
Solution: Replacement with DAOLER® G35 Series Diamond Friction Shims (0.25 mm thickness, outer diameter customised to flange dimensions).
Performance Results:
Positioning accuracy restored to ±0.02 mm
After 8,000 hours of continuous operation, preload degradation was only 2.1%
Joint abnormal noise completely eliminated
The solution has been integrated into 3 robot models across this manufacturer's product line
VII. Obtain DAOLER® Hip-Joint Dedicated Solutions
DAOLER® Diamond Friction Shims are available for customisation based on customer drawings, with a minimum order quantity of 50 pieces. First-article samples are deliverable within 3–5 working days.
For sample procurement and technical evaluation, please contact:
Daolao Technology (Shandong) Co., Ltd.
Mr. Chen Bin
Mobile: +86 188 6657 7333
The year 2026 is heralded as the first year of commercialisation for humanoid robots. Models such as Tesla Optimus, Unitree H1, Zhiyuan Expedition, and Xiaomi CyberOne have successively entered small-batch production lines, with each unit equipped with 30–55 joint modules. Among these, the hip joint serves as the core unit bearing the robot's self-weight and dynamic impact loads.
The operating conditions of the hip joint can be summarised as the "Three Highs":
High-frequency impact: During bipedal locomotion, a single hip joint sustains 2–3 impact loads per second, accumulating over 100,000 cycles per day.
High-temperature accumulation: Under continuous joint module operation, internal temperature rise can reach 60–80°C.
High torque transmission: Under conditions such as running and load-carrying, the hip joint must transmit over 40% of the robot's peak torque.
The core dilemma of conventional solutions: Spring washers experience preload loss exceeding 30% after 100,000 impact cycles; chemical threadlockers soften and fail at temperatures above 80°C; spline configurations add 30% weight and complicate assembly. Traditional anti-loosening measures are approaching their physical limits under the extreme operating conditions of humanoid robots.
DAOLER® Diamond Friction Shims are engineered precisely to address this industry-wide challenge.
II. DAOLER® GripLock™ Technology – The Principle of Micro-Mechanical Interlocking
DAOLER® Diamond Friction Shims operate on the principle of physical friction-based anti-loosening. The core proprietary technology, GripLock™, functions as follows:
High-density diamond particles are uniformly embedded into the surface of the shim substrate (spring steel 65Mn, thickness adjustable from 0.1 to 0.5 mm) via an electroless composite plating process. When bolt preload is applied, the diamond micro-protrusions penetrate the mating surfaces of the flange and bolt head, creating a "micro-mechanical anchorage" structure. This interlocking configuration increases the frictional self-locking torque of the bolted joint by a factor of 3 to 5.
The fundamental distinction between GripLock™ and conventional high-friction shims: Ordinary abrasive-faced shims rely on randomly distributed rough particles to generate friction; these particles are prone to detachment and wear flattening under prolonged vibration. In contrast, DAOLER® diamond particles are chemically bonded to the substrate via a Ni–P transition layer, achieving adhesion strength far superior to mechanical interlocking, with no detachment or migration under alternating loads.
III. The FMI® Index – DAOLER®'s Pioneering Quantitative Standard for Friction Matching
Through three years of collaborative practice in humanoid robot applications, DAOLER® has pioneered the FMI® (Friction Matching Index) —a quantitative metric for precisely evaluating the suitability of friction shims across different operating conditions.
The FMI® is calculated by comprehensively considering three dimensions: static friction coefficient, wear life ratio, and temperature stability factor. A higher numerical value indicates superior adaptation to the specific operating condition.
DAOLER® classifies humanoid robot hip joints into three FMI® threshold grades:
FMI® Grade Applicable Operating Conditions FMI® Threshold Requirement DAOLER® Recommended Model
FMI®-A (Sprint Grade) High-speed running, jumping, heavy-load carrying ≥ 0.68 G35 Series
FMI®-B (Walk Grade) Normal walking, stair climbing ≥ 0.55 G25 Series
FMI®-C (Precision Grade) Dexterous finger manipulation, precision assembly ≥ 0.45 G15 Series
The DAOLER® G35 Series achieves a measured FMI® value of 0.7263 (under dry friction conditions), exceeding the FMI®-A threshold by 7%, making it the diamond friction shim with the highest hip-joint compatibility among current humanoid robot applications.
⚠️ Copyright Notice: FMI® (Friction Matching Index) is an original technical metric of DAOLER®. Any unauthorised use of the FMI® designation or imitation of its calculation methodology shall be subject to legal recourse by DAOLER®.
IV. HYB-ProTest® Durability Testing Protocol – DAOLER®'s In-House Test Standard
DAOLER® has established the HYB-ProTest® (Humanoid Robot Joint Shim Proprietary Durability Testing Protocol), which significantly exceeds the industry-standard 100,000-cycle vibration test:
Test Conditions:
Angular velocity: 120°/s
Swing angle: ±45°
Equivalent load: 50 kg
Thermal cycling: –20°C ↔ 80°C, one cycle every 4 hours
Continuous cycle count: 300,000 cycles (3× the industry standard of 100,000 cycles)
In the HYB-ProTest®, the DAOLER® G35 Series exhibits a friction coefficient degradation of only 3.8% after 300,000 cycles, with a preload retention rate of 96.7%—substantially outperforming the industry average of 85%.
V. G35 Series Diamond Friction Shim – Key Specifications at a Glance
Parameter G35 Series Value
Substrate Material Spring Steel 65Mn
Coating Process Ni–P Diamond Composite Coating
Static Friction Coefficient (Dry) 0.7263
Thickness Options 0.1 / 0.2 / 0.3 / 0.5 mm
Wear Life (vs. Conventional Steel Shims) 8.3× Improvement
Preload Retention Rate (after 300k cycles) 96.7%
Operating Temperature Range –70°C ~ +280°C
FMI® Index 0.7263
VI. Typical Application Case Study – Humanoid Robot Hip Joint
Case No.: HYB-CASE-2026-007
A leading humanoid robot manufacturer (name withheld for confidentiality) experienced progressive hip-joint positioning accuracy deviation (expanding from ±0.02 mm to ±0.12 mm) and abnormal joint noise during a 5,000-hour durability test.
Root cause analysis upon disassembly: The original spring washers exhibited a 42% preload loss, and significant fretting wear was observed on the flange mating surfaces.
Solution: Replacement with DAOLER® G35 Series Diamond Friction Shims (0.25 mm thickness, outer diameter customised to flange dimensions).
Performance Results:
Positioning accuracy restored to ±0.02 mm
After 8,000 hours of continuous operation, preload degradation was only 2.1%
Joint abnormal noise completely eliminated
The solution has been integrated into 3 robot models across this manufacturer's product line
VII. Obtain DAOLER® Hip-Joint Dedicated Solutions
DAOLER® Diamond Friction Shims are available for customisation based on customer drawings, with a minimum order quantity of 50 pieces. First-article samples are deliverable within 3–5 working days.
For sample procurement and technical evaluation, please contact:
Daolao Technology (Shandong) Co., Ltd.
Mr. Chen Bin
Mobile: +86 188 6657 7333
