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Ultra-high molecular weight polyethylene (UHMWPE) is widely used in sliding parts, wear-resistant linings and mechanical parts due to its extremely low friction coefficient. In order to accurately measure the friction performance of UHMWPE, the following standard test methods are usually used.

1. Test Standards

UHMWPE friction coefficient test is usually based on the following international standards:

ASTM D1894 (Measurement of dynamic and static friction coefficients of plastics)

ISO 8295 (Friction coefficient test of plastic films and sheets)

ASTM G99 (Pin-on-Disk Test)

ASTM G115 (Reciprocating Wear Test)

2. Main test methods

(1) ASTM D1894 / ISO 8295 - Inclined or flat friction test

Applicable to: UHMWPE materials such as thin sheets and flat plates

Test principle:

UHMWPE sheet is used as the bottom surface and another material (such as metal, rubber or another piece of UHMWPE) is used as the sliding surface.

Apply a certain pressure to make the slider slide on the UHMWPE sheet.

Record the static friction coefficient (COF_s) at the beginning of sliding and the dynamic friction coefficient (COF_d) during sliding.

Calculation formula: μ=F/N

Where:

μ: friction coefficient; F: friction force measured during sliding (N); N: applied normal force (N)

Result analysis:

The static friction coefficient (COF_s) of UHMWPE is about 0.05 - 0.20.

The dynamic friction coefficient (COF_d) is about 0.05 - 0.10, which is lower than most engineering plastics.

(2) ASTM G99 - Pin-on-Disk Test

Applicable to: high-precision friction testing, study of the friction performance of UHMWPE on different material surfaces

Test principle:

Pin: a small cylinder made of UHMWPE, usually with a diameter of 4-10 mm.

Disk: metal, ceramic, glass or other materials are selected as the friction dual surface.

Let the UHMWPE pin slide on the rotating disk and measure the friction force.

Experimental variables:

Load (usually 1 - 10 N)

Sliding speed (0.1 - 1.0 m/s)

Test temperature (room temperature or high temperature)

Test results:

Friction against stainless steel: Friction coefficient 0.08 - 0.12

Friction against glass: Friction coefficient 0.05 - 0.09

Friction against UHMWPE itself: Friction coefficient 0.10 - 0.20

(3) ASTM G115 - Reciprocating Wear Test

Applicable to: dynamic reciprocating friction, simulating real sports environment

Test method:

Apply a certain normal load to the surface of UHMWPE material.

Measure the friction resistance through reciprocating motion.

Record the friction change at different sliding distances.

Advantages:

It can test the friction change of UHMWPE in long-term use.

Applicable to artificial joints, conveyor slides, wear-resistant plates and other application scenarios.

3. Factors affecting the friction coefficient of UHMWPE