Keywords: Wide Working Conditions, PFPE, PTFE, Viscosity Index, EHL
The event settings for the 2nd World Humanoid Robot Games have been announced: clothes folding, cooking, cleaning, object passing, bed making, waste sorting — 21 real-life scenes.
From an engineer’s perspective, the essence of these 21 competitions is not “difficulty upgrade” — it is “working condition logic being rewritten.”
Industrial production lines grasp the same part millions of times with predictable loads, programmable actions, and controlled temperature and humidity. Tooth surface contact stress distribution is convergent. Real-life scenes are completely the opposite: grasping an egg (shell thickness 0.3mm) → carrying a soup pot (3–4 kg) → pinching a green bean (tens of grams). Weight magnitude jumps, surface friction coefficient fluctuates from 0.2 to 1.0+. Motion modes switch frequently between light pinching, lifting, shaking, and placing within 2 seconds. Kitchen 40°C+ with oil smoke vs. balcony dust vs. outdoor temperature differences — complex compound environments.
This “unstructured environment” puts forward three entirely new wide-condition adaptability requirements for dexterous hand planetary reducer grease — each directly determines whether the dexterous hand can operate “stably.”
Challenge 1: Grasping Object Changes → Random Loads → Oil Film Needs Millisecond-Level Response
Under elastohydrodynamic lubrication (EHL) state, oil film thickness is a function of speed, load, and base oil viscosity. When load suddenly changes, the oil film needs to “re-squeeze” to a new thickness — this response time is millisecond-level.
Morning: grasping a handful of green beans (tens of grams). Noon: carrying a pot of soup (3–4 kg). Afternoon: pinching an egg again. Contact stress on the planetary reducer input jumps in magnitude within a short time.
If the grease base oil viscosity index is low, viscosity collapses with temperature change, and squeeze response time further lengthens.
Mineral oil viscosity index (VI) is only 90–100. Perfluoroether oil (PFPE) VI is 50–350. Silicone oil VI is 190–500. Wide temperature range keeps oil film thickness more stable and better withstands random load spectrum fluctuations.
Challenge 2: Motion Mode Switching → Oil Film Lag Window → PTFE Solid Film Instant Rescue
Among competition events: “clothes folding” is light pinch + sliding friction. “Lifting a water bottle” is lifting + impact load. “Shaking a seasoning bottle” is high-frequency micro-amplitude oscillation. The dexterous hand switches from “light pinch” to “lifting heavy object” within 2 seconds, with tooth surface contact stress spiking.
When load suddenly changes, there is a dangerous zone: oil film has not yet established thickness, tooth surface is already bearing new contact stress, and metal-to-metal direct contact probability rises significantly. Engineers call this the “boundary lubrication window.”
In this window, base oil viscosity alone is insufficient. PTFE solid lubricant is needed for instant rescue. PTFE (polytetrafluoroethylene) friction coefficient is 0.05–0.1 with working temperature upper limit of 275°C. It can directly form a “transfer film” on tooth surfaces, providing boundary protection independent of oil film thickness. Oil film + solid film double insurance is especially important for dexterous hands with high-frequency working condition switching.
Challenge 3: Environmental Uncertainty → Temperature-Humidity-Dust Compound → Oil Needs “Stability”
Kitchen 40°C+ high humidity + oil smoke. Bedroom 20°C+ low humidity. Balcony with dust. Outdoor with day-night temperature difference. Compound environment makes three concurrent demands on grease:
- **High viscosity index:** Ensures oil film thickness remains stable from -20°C to 150°C, without dramatic decay due to day-night temperature swings or scene switching.
- **Low oil separation:** Below 10% at 100°C/24h is the engineering threshold. Otherwise, at high temperatures base oil escapes and thickener dries out, leading to direct metal-to-metal tooth contact.
- **Hydrophobicity:** Kitchen humidity, water splashing, outdoor rain work — all cause ordinary grease to emulsify and fail. Fluorinated oil-based grease has excellent hydrophobicity due to fluorocarbon chain chemical inertness. Water wash loss is far lower than mineral oil-based grease.
Six Hard Indicators for Wide-Condition Grease
Returning to selection — a dexterous hand planetary reducer dedicated grease that can simultaneously withstand all three challenges must meet six indicators in coordination:
- 1. High viscosity index (PFPE / silicone base): oil film changes minimally with temperature
- 2. Contains PTFE solid lubricant: provides boundary protection during oil film lag window
- 3. Oil separation rate < 10%: framework does not collapse at high temperature
- 4. Low evaporation loss: as low as possible at 100°C/24h
- 5. Wide temperature range -50°C to 220°C: covers south-north climate and kitchen-outdoor temperature differences
- 6. Hydrophobic fluorinated oil or silicone base: resistant to humid heat and water washing
The X500 (VNOVO) grease has all six indicators designed in synergy: high viscosity index fluorinated oil base oil ensures oil film stability. PTFE solid lubricant provides boundary protection during instant working condition switching. Less than 10% low oil separation rate ensures long-term framework stability. -50°C to 220°C wide temperature range covers south-north and kitchen-outdoor temperature differences. Fluorinated oil’s inherent hydrophobicity handles humid dusty environments.
This combination is essentially not “strongest in any single indicator” but “wide-condition coordination all met.” This is the core requirement of real-life scenes for dexterous hand planetary reducer grease.
Why This Issue Is Only Surfacing Now
Past humanoid robots were primarily oriented toward industrial production lines. With standardized workpieces + controlled environments + predictable loads, mineral oil-based grease + complex lithium complex thickener basically worked.
The 21 real-life scene competitions pushed the industry onto the “unstructured environment” track. Mineral oil-based grease viscosity index ceiling, conventional thickener shear stability weaknesses, and single extreme pressure additive working condition coverage limitations were all simultaneously exposed.
This is not just “replacing with a more expensive grease” — it is the redefinition of selection logic.
Search “VNOVO” or visit our website for more information.
