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How to Measure the Slip Resistance of Safety Shoes?
2026-03-06
I. Why is Slip Resistance Testing for Safety Shoes Critical?
In industries such as petrochemicals, food processing, and construction, slips on wet or slippery surfaces account for over 35% of all workplace injuries. The slip resistance of safety footwear directly impacts worker safety. Test results serve not only as the core basis for product compliance certification but also as a critical component of corporate safety management. Scientific slip resistance testing requires simulating real-world conditions to quantify friction coefficients and critical slip angles, thereby avoiding errors inherent in “subjective evaluation.”
II. Testing Standards
| Core Standard Number | Test Method | Key Metric |
| EN ISO 20345:2021 | Slope Method (SRR) | Critical slip angle ≥12° (Basic Level)/15° (Intermediate Level)/18° (Advanced Level) |
| ASTM F2913 | Plane Traction Method | Dynamic coefficient of friction (COF) ≥0.3 |
| GB 21148-2020 | Coefficient of Friction Method + Inclined Platform Method | Wet friction coefficient ≥0.28 (Tile + Detergent) |
| GB/T 3903.6-2017 | Static / Dynamic Coefficient of Friction Determination | Dry COF ≥0.4 |
III. Two Core Measurement Methods (Including Instrument Operation Procedures)
1. Incline Method
Test Principle: Simulates the center-of-gravity shift during human walking. By progressively increasing the incline angle of the platform, it captures the critical angle at which the shoe sample begins to slip, converting it to the friction coefficient μ = tanθ.
Specialized Instrument: Inclined Plane Friction Tester (Angle Range: 0°–85°, Accuracy: 0.01°)
1.1 Core Configuration: Servo motor-driven platform (tilt rate 1.5°/sec), laser displacement sensor, standard contact surfaces (ceramic tile / steel plate), medium supply system
1.2 Operating Procedure:
a. Sample Pre-treatment: Shoe samples undergo 50 km break-in to ensure sole tread patterns exhibit no initial wear
b. Environmental Calibration: Temperature 23±2°C, Humidity 50±5%, contact surface coated with standard medium (25% glycerin aqueous solution / SAE 10W-30 engine oil)
c. Test Execution: Secure shoe samples to platform, initiate uniform heating from 6°, record critical slip angle (6 pairs × 10 tests per sample)
d. Rating classification: ≥18° denotes high-level slip resistance (suitable for petrochemical/food service industries), 15°–17° denotes medium level (food processing), 12°–14° denotes basic level (general workshops)
2. Pendulum Method
Testing principle: Simulates sole sliding via pendulum impact, measures energy loss during impact to calculate static friction coefficient.
Specialized Equipment: Pendulum friction tester (adjustable impact energy 0-5J)
2.1 Applicable Scenarios: Dry/slightly wet environments, rapid screening of basic sole slip resistance
2.2 Key Parameters: Test speed 0.3m/s±0.02m/s, contact pressure 500N±10N
2.3 Precautions: Must be evaluated in conjunction with dynamic test results to avoid misguided selection based solely on static data
IV. Testing Essentials
1. Environmental Control: Water film thickness strictly controlled at 1-2mm for wet tests; oil film thickness 0.5mm±0.05mm for oil contamination scenarios
2. Sample Requirements: Collect no fewer than 6 pairs from the same batch, covering large/medium/small shoe sizes. Exclude worn samples with tread depth <1.6mm.
3. Instrument Calibration: Calibrate annually through a CNAS-accredited measurement traceability system. Force sensor accuracy must reach ±0.1N.
4. Medium Selection:
4.1 Humid environments: 25% glycerin aqueous solution
4.2 Oily workshops: SAE 10W-30 engine oil
4.3 Medical settings: 0.9% sodium chloride solution (simulating disinfectant environments)
V. Industry Application Scenarios and Model Recommendations
Food service kitchens (oil-water mixtures): Slope method (engine oil medium), Advanced (≥18°)
Construction Sites (Cement/Standing Water): Slope Method + Pendulum Method, Intermediate (≥15°)
Operating Rooms (Disinfectant Floors): Plane Traction Method, COF ≥0.35
Petrochemical Workshops (Oily Steel Plates): Slope Method (SAE 10W-30), Advanced (≥18°)
VI. Common Testing Misconceptions and Solutions
1. Misconception 1: Testing only dry conditions → Solution: Mandatory inclusion of wet/oily condition tests (80% of actual accidents occur in slippery environments)
2. Misconception 2: Neglecting sole hardness → Solution: Simultaneous measurement of Shore hardness (65-75 Shore A optimal; excessive hardness reduces contact area)
3. Misconception 3: Insufficient test cycles → Solution: Test each sample ≥60 times, discard 3% outliers, then calculate average
4. Misconception 4: Inadequate contact surface cleaning → Solution: Use ultrasonic cleaning equipment to remove residual media contamination