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D5859-96 – Standard Test Method Technical Guide
📏 Scope and Application of D5859-96
ASTM Designation D5859-96 defines a standard test method for determining the traction of footwear on painted walkway surfaces. This method is specifically designed to measure slip resistance under both dry and wet conditions and is applicable for use in both the laboratory and the field. According to Section 1.2 of the standard, the values stated in inch-pound units are to be regarded as the standard, with SI values provided for information only.
The standard references Terminology F 1646 for the formal definitions of “Friction” and “Coefficient of Friction.” As stated in Section 1.3, users of this standard are responsible for establishing appropriate safety and health practices and determining the applicability of regulatory limitations prior to performing any test.
| 🟦 Parameter | 📐 Specification |
|---|---|
| Test Material | Footwear (sole/heel assemblies) |
| Test Surface | Painted walkway surfaces |
| Environmental Conditions | Dry and wet |
| Testing Location | Laboratory and field |
| Key Measured Output | Static Coefficient of Friction (Slip Index) |
⚙️ Test Procedure and Instrument Mechanics
The variable incidence tester operates using a mechanism that is independent of gravity and is self-powered by a miniature carbon dioxide cartridge. Unlike the James and Hunter machines, it utilizes an articulated strut and a fluidics actuation system. This system applies the load to the slider shoe instantaneously, specifically overcoming the well-known “stiction” problem that arises from the delay between the time the slider is set down onto the surface and the time it starts to slip.
As the test progresses, the shoe descends, makes contact with the substrate, and is subjected to a constant vertical load in addition to an increasing horizontal (tangential) load until slip occurs. The tangent of the angle that the tester makes with respect to the vertical at the instant of slip is taken to be the ratio of the horizontal and vertical force components, and thus the coefficient of friction. The angle read from the protractor scale at which slippage first begins is recorded as the slip index or the static coefficient of friction.
| ⚡ Component / Feature | 🎯 Function / Description |
|---|---|
| Power Source | Miniature Carbon Dioxide (CO₂) Cartridge |
| Mechanical Structure | Articulated strut |
| Load Application Mechanism | Fluidics actuation (instantaneous load application) |
| Raw Measured Parameter | Slip Angle (θ) from the protractor scale |
| Calculated Coefficient | Static COF = tan(θ) / Slip Index |
⚠️ Safety and Regulatory Compliance: Per Section 1.3 of D5859-96, this test method does not purport to address all safety concerns. It is the strict responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
💡 Terminology and Equipment Note: An editorial note (e1) indicates that the definitions for “Friction” and “Coefficient of Friction” are now provided by reference to Terminology F 1646. Furthermore, the apparatus described (often referred to as the English XL) is covered by a patent, and interested parties are invited to submit alternatives to the Committee on Standards.
❓ Frequently Asked Questions
🔍 What specific type of coefficient of friction does the variable incidence tester measure?
The variable incidence tester measures the static coefficient of friction (referred to in the standard as the “slip index”). This is derived from the tangent of the angle at which slippage just begins to occur, as read from the protractor scale.
💡 How does the variable incidence tester overcome the “stiction” problem common in other slip testers?
It overcomes the “stiction” problem through its fluidics actuation system, which applies the load to the slider shoe instantaneously. This eliminates the critical delay between the time the shoe is set down onto the surface and the time it starts to slip.
⚡ What is the primary power source for the variable incidence tester described in D5859-96?
The instrument is self-powered by a miniature carbon dioxide (CO₂) cartridge. This design allows the tester to operate independently of gravity, making it equally suitable for controlled laboratory testing and field work.
📌 Under what surface and environmental conditions is this test method applicable?
According to Section 1.1 of the standard, this test method covers the measurement of traction on painted walkway surfaces under both dry and wet conditions.