Comparison of footwear anti-slip test methods

The slip resistance of shoes directly affects safety and comfort during wear. Poor slip resistance can easily lead to slipping and falling while walking. Slips, trips, and falls are already recognized as one of the main causes of accidents in workplaces, public areas, and home environments. The slip resistance of footwear can be represented by the dynamic and static coefficients of friction between the sole and the ground. A higher coefficient of friction indicates better slip resistance.

Basic Principle of Slip Testing

From a mechanical perspective, the sliding friction force between two contacting objects depends on two factors: the coefficient of friction between their contact surfaces and the normal force applied to the object. The slip resistance between two contacting objects can be represented by the magnitude of the coefficient of friction. According to tribological principles, μ = f/N, where μ is the coefficient of friction, f is the friction force, and N is the normal force. It can be seen that the coefficient of friction is a dimensionless ratio, representing the force required to initiate movement relative to the normal force. The sliding friction coefficient is related to the materials of the contacting objects, surface smoothness, dryness/wetness, surface temperature, relative motion speed, and the normal force between the objects.

Comparison of Slip Resistance Test Methods for Footwear

Currently effective domestic and international test methods for the slip resistance of footwear are detailed below.

GB/T 3903.6 “Footwear – General Test Methods – Slip Resistance

This method’s principle involves placing the sample on a test plane (glass plate), using glycerol as a lubricant, applying a given load (25 kg), and then moving the sample horizontally relative to the test plate via a lateral traction force to measure the dynamic friction force and calculate the dynamic coefficient of friction . Although this is a general test method for footwear, it has the following shortcomings:
  1. When calculating the coefficient of friction, the standard specifies “Vertical load = Last mass + Fixture mass + Counterweight mass”. Different samples require different test lasts, leading to different vertical loads, yet the coefficient of friction is related to the vertical load.
  2. The specification for the test plate is insufficiently detailed, only specifying a glass plate without surface scratches, lacking an effective calibration method to ensure uniformity of test plates.
  3. It specifies sample shoe sizes as men’s 255, 260, 265 and women’s 235, 240, 245, making it impossible to test finished children’s shoes with smaller sizes.
  4. According to a report by Shi Yiwei (“Research and Discussion on Footwear Slip Resistance and Testing Equipment”), the repeatability of test results using this method is poor.

HG/T 3780 “Test Method for Static Slip Resistance of Footwear”

This method’s principle involves placing the specified sample horizontally on a required friction panel (ground glass) with the test surface facing down, applying a certain load, pulling the sample at a certain speed using a horizontal pulling method, measuring the maximum pulling force, and calculating the static coefficient of friction to measure the sample’s static slip resistance. This method has the following issues:
  1. It is only applicable for testing the static slip resistance of footwear outsoles, heels, or related outsole materials, not for complete footwear.
  2. Although the friction panel is specified as “float ground glass with a specular gloss of 4”, actual calibration results show significant variations in the specular gloss across different areas of the ground glass surface, making it difficult to achieve uniform specular gloss accurately.
  3. For heel surfaces with small areas, it cannot meet the sample cutting requirements.

TM 144 Footwear Slip Resistance Tester DW9530

Footwear Slip Resistance Tester, also called Footwear Friction Tester or Shoe Dynamic Slip Resistance Tester , is internationally adopted slip resistance tester used to measure the dynamic coefficient of friction (CoF) of whole shoe sole, forepart or heel, for evaluation of shoe slip resistance.FYI is a leading manufacturer and supplier of high quality footwear slip resistance tester. We offer cost effective testing solutions and equipments for various industrial applications.
More about the footwear slip resistance tester in FYI

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