The coefficient of friction (COF) of materials changes significantly with temperature, making temperature-dependent friction testing essential for product safety, reliability, and regulatory compliance across industries. This technical guide explains the key international and national testing standards—such as ISO 8295, ASTM D1894, ASTM G99, and ASTM G77—used by accredited third-party laboratories to measure static and kinetic friction behavior from cryogenic to elevated temperatures.
Technical Overview
The coefficient of friction (COF) is a dimensionless value that quantifies the resistance to sliding between two contacting surfaces. It is typically expressed as a static coefficient (the force required to initiate motion) and a kinetic coefficient (the force required to sustain motion). Because friction is not an intrinsic material constant but a system property, it is strongly influenced by operating temperature, normal load, sliding speed, surface finish, and the surrounding environment.
Temperature dependence is particularly critical for polymeric materials, where viscoelastic transitions cause dramatic COF changes near the glass transition or softening point; for metals, where surface oxidation and lubricant viscosity vary with heat; and for rubber, where hysteresis losses shift with thermal conditions. Consequently, a material that performs acceptably at room temperature (23 °C) may fail in service at –40 °C or +150 °C.
Several standards organizations publish recognized test methods for friction measurement, including ISO, ASTM International, EN, GB (Chinese national standards), and JIS. While many baseline methods specify standard laboratory atmospheres, they can be combined with environmental chambers and temperature-controlled fixtures to characterize the friction–temperature relationship across a defined thermal range.
Testing Samples
Polymer Films and Sheeting
Flexible packaging films such as polyethylene (PE), polypropylene (PP), PET, and multilayer laminates are commonly tested against themselves or against stainless steel. Temperature-dependent COF data are essential because films sliding on hot filling lines, heat tunnels, or cold-storage conveyors behave very differently from room-temperature laboratory conditions.
Rubber and Elastomeric Components
Seals, O-rings, tires, conveyor belts, and gaskets made from NBR, EPDM, FKM, silicone, or thermoplastic elastomers are tested against metal, glass, or polymer counterfaces. Friction at extreme temperatures governs sealing integrity, stick-slip tendency, and wear life.
Metals, Alloys, and Bearing Materials
Steel, aluminum, copper alloys, self-lubricating bushings, sintered bronze, and engineered bearing couples are evaluated under dry and lubricated conditions. Elevated-temperature testing reveals oxide-layer effects and lubricant breakdown that are invisible at ambient conditions.
Ceramics, Composites, and Coatings
Fine ceramics, carbon fiber composites, PTFE-based coatings, DLC coatings, and thermal spray layers are tested using ball-on-disc or block-on-ring configurations, often at high temperatures relevant to braking, aerospace, and tooling applications.
Lubricants and Functional Fluids
Greases, gear oils, metalworking fluids, and transmission fluids are assessed by measuring the friction of a defined tribological couple lubricated with the candidate fluid across a temperature ramp, following friction and wear test methods from ASTM and ISO.
Testing Items
Typical measurands and test configurations for temperature-dependent friction characterization include:
- Static coefficient of friction as a function of temperature (e.g., at –40 °C, 23 °C, 60 °C, 100 °C, 150 °C)
- Kinetic (dynamic) coefficient of friction as a function of temperature at specified sliding speeds
- Multi-temperature-point friction mapping and continuous temperature-sweep profiles
- Stick-slip behavior and friction force fluctuation analysis under thermal cycling
- Combined friction and wear evaluation (wear rate, wear scar dimension) at controlled temperatures
- Friction of films against reference counterfaces such as polished stainless steel at film-processing temperatures
- Comparison of dry versus lubricated friction across the service temperature range
- Post-test surface characterization (microscopy, roughness) to interpret friction transitions
Testing Methods
Horizontal Sled Method for Films and Flat Specimens
ISO 8295 and ASTM D1894, along with the equivalent Chinese standard GB/T 10006, define the horizontal plane/sled method widely used for plastic films and sheeting. A sled of defined mass and contact area is dragged across the specimen while the force is recorded, yielding both static and kinetic COF. For temperature studies, the standard apparatus is fitted with a thermally controlled chamber so that the sled, film, and counterface all reach the set temperature before measurement. Conditioning of specimens is normally performed per ISO 291 or ASTM D618 prior to testing.
Pin-on-Disc Method
ASTM G99 and ISO 20808 describe rotating pin-on-disc (or ball-on-disc) testing, in which a stationary ball or pin presses against a rotating disc under a defined load. With an integrated furnace or cryogenic enclosure, this method measures COF and wear at temperatures up to several hundred degrees Celsius, making it a mainstay for metals, ceramics, and coatings.
Block-on-Ring Method
ASTM G77 evaluates friction and wear of materials in sliding contact using a block pressed against a rotating ring. It is frequently applied to lubricants and bearing couples, and temperature-controlled variants quantify how friction rises when lubricant films thin at elevated temperatures.
Reciprocating and Thrust-Washer Methods
ASTM G133 (linearly reciprocating ball-on-flat) and ASTM D3702 (thrust washer for self-lubricated materials) provide additional geometries suited to oscillating contacts and bearing surfaces. Both can be adapted with heated or cooled stages to build COF-versus-temperature curves.
Reporting and Data Quality
ASTM G115 provides guidance for measuring and reporting friction coefficients, emphasizing documentation of material pairing, surface preparation, load, speed, temperature, environment, and repeatability. A rigorous temperature-dependent study typically includes a minimum of three replicates per setpoint, equilibrium soak times at each temperature, and a clear statement of measurement uncertainty.
Applications
Temperature-dependent friction data support design, quality control, and compliance decisions in many sectors:
- Packaging: verifying that films run reliably on hot-fill, pasteurization, and chilled conveying lines without slip or blocking
- Automotive: brake friction materials, clutch plates, timing chain guides, and seal compatibility across under-hood temperature ranges
- Aerospace: cryogenic and high-temperature tribology for actuator components, landing hardware, and composite structures
- Industrial machinery: bearing, bushing, and guide-element selection for ovens, cold rooms, and outdoor service
- Sealing systems: predicting seal friction and stick-slip in hydraulic and pneumatic equipment under thermal cycling
- Flooring safety: dynamic COF evaluation of tiles and flooring under wet conditions, referencing ANSI A137.1 and slip-resistance test methods such as ISO 13287 for footwear
- Metal forming: assessing lubricant performance during hot and warm working of steels and aluminum alloys
FAQ
Why does the coefficient of friction change with temperature?
In polymers and rubbers, temperature shifts the material between glassy, transitional, and rubbery states, altering real contact area and adhesion. In metals, heat promotes oxide growth and changes surface hardness, while lubricants lose viscosity and film thickness at high temperature. Ice or condensation formation at low temperature can also drastically reduce friction.
Which standards are most commonly applied for temperature-related COF testing?
Baseline friction methods include ISO 8295, ASTM D1894, and GB/T 10006 for films; ASTM G99, ISO 20808, ASTM G77, ASTM G133, and ASTM D3702 for rigid tribological couples; and ASTM G115 for reporting practice. ISO 6601 provides general guidance on friction and wear testing of plastics. Temperature-controlled variants of these methods are used to establish the friction–temperature relationship.
What temperature range and how many setpoints are typical?
Common service-driven ranges are –40 °C to +150 °C for polymer and rubber components, and up to 500 °C or higher for metals, ceramics, and coatings using furnace-equipped tribometers. A typical study uses four to six setpoints with a minimum of three replicates each, plus a room-temperature reference measurement at 23 ± 2 °C and 50 ± 5 % relative humidity.
How long must specimens soak at each temperature?
Sufficient dwell time must be allowed for the specimen, counterface, and fixtures to reach thermal equilibrium, typically 15 to 60 minutes depending on specimen thickness and thermal mass. Instrumented confirmation of the actual interface temperature is strongly recommended before sliding begins.
How should results be reported?
Reports should state the material pairing, surface preparation, nominal pressure, sliding speed, temperature at the interface, static and kinetic COF values with standard deviations, the presence of stick-slip, and any wear or surface observations. Traceability to the applied standard method and calibration records of the force and temperature sensors should be included.
Can accredited third-party laboratories perform these tests?
Yes. Accredited third-party laboratories routinely conduct temperature-dependent coefficient of friction testing under ISO, ASTM, GB, EN, and JIS methods, providing independent data for supplier qualification, failure analysis, research and development, and regulatory submission.