What Is Coefficient of Friction?
The coefficient of friction test is a test in which the static and dynamic coefficients of friction are calculated from the force measured while a sled of defined weight is pulled at a constant speed over the specimen surface.
Purpose of Coefficient of Friction
The purpose is to numerically determine the material's slipperiness, checking packaging-line performance, stacking safety and surface quality.
Which Products Is Coefficient of Friction Applied To?
- Plastic film and packaging
- Coated paper and cardboard
- Floor coverings
- Automotive interior surfaces
In Which Sectors Is Coefficient of Friction Used?
Standards Related to Coefficient of Friction
- ISO 8295
- ASTM D1894
- ISO 15359
Coefficient of Friction Conditions
- Sled weight
- Defined in the standard; typically 200 g in ISO 8295
- Tensile speed
- Constant rate per the standard; typically 100 mm/min
- Contact pair
- Defined as film-to-film or film-to-metal
- Environment
- 23 °C ± 2 °C and 50% ± 5 relative humidity
Equipment for Coefficient of Friction
- Universal testing machine or friction-test rig
- Standard sled and weight set
- Flat test table
- Conditioning chamber
Sample Requirements for Coefficient of Friction
- The specimen must be flat, free of wrinkles and clean
- The test surface (outer/inner) must be specified
- Generally at least five measurements per set
- Specimens must be handled with gloves
Duration of Coefficient of Friction
Duration per measurement is short; a set including conditioning is completed within half a working day.
Coefficient of Friction Procedure
- 1Specimens are conditioned.
- 2The specimen is stretched taut and fixed to the test table and the sled surface.
- 3The sled is placed on the specimen.
- 4Pulling is applied at a defined speed; The force is recorded continuously.
- 5The initial peak is used for the static, and the steady-state region for the dynamic, coefficient of friction.
Coefficient of Friction Acceptance Criteria
The acceptance criterion is given in the specification as a range for the static and dynamic coefficients of friction. Both a too-high and a too-low value can cause problems.
Evaluation of Results
Static and dynamic coefficients are reported separately. Results cannot be compared when the contact pair or surface orientation changes.
Coefficient of Friction Report
- Standard applied
- Sled weight and pull rate
- Contact pair and tested surface
- Static and dynamic coefficients of friction
- Conditioning conditions
Accreditation
EUROLAB holds internationally recognised accreditation obtained from accreditation bodies party to the IAF and ILAC multilateral recognition arrangements, under ISO/IEC 17025 for laboratory testing, ISO/IEC 17020 for inspection and surveillance, and ISO/IEC 17021-1 and ISO/IEC 17065 for system and product certification. This chain ensures the reports and certificates issued are accepted worldwide.
Whether this test can be offered within accredited scope depends on your product and the standard applied; since accreditation is method-based, the scope is confirmed in writing at the quotation stage.
Scope and authorisationsRelated Regulations
- Packaging product specifications
Mekanik Testler — What Does This Testing Field Cover?
The section below describes the field that the Coefficient of Friction test belongs to; the conditions and acceptance criteria of this particular test are given in the sections above. The scope specific to your product is confirmed in writing at the quotation stage.
Mechanical testing measures how a material or a part behaves under force. The family ranges from static loading (tension, compression, bending) to time-dependent behaviour (fatigue, creep), and from hardness and wear to fracture toughness.
What these tests have in common is that the result is reported as a MATERIAL PROPERTY. Yield strength or hardness is not a conformity decision; it is numerical data against which the design and the product standard will compare. Mechanical test reports are therefore usually an input to an engineering decision rather than to a product approval — material selection, safety factor, life prediction.
The distinction between static and dynamic behaviour is the key to understanding the field. A part may appear entirely unstressed under a static load yet break under repeated loading; fatigue fracture occurs at stresses well below the yield strength and gives no warning. For rotating, vibrating or cyclically loaded parts, a tensile test alone is therefore not sufficient evidence.
Test conditions determine the result, and this is critical for the readability of the report: specimen geometry, loading rate, temperature, conditioning and the gripping arrangement. The same material gives different values under different conditions. In plastics the rate effect is very pronounced, in metals the temperature effect; in composites the specimen orientation changes the result entirely.
Hardness is the most misused measurement in the field. Because it is fast, close to non-destructive and inexpensive, it is often used in place of strength. Conversion tables from hardness to strength exist, but they are APPROXIMATE and depend on the material group; using them as the sole evidence in material acceptance is wrong.
The fracture mechanics side requires a specific competence. Fracture toughness and fatigue crack growth rate measurements make it possible to calculate how long a cracked structure will last; they are the basis of damage-tolerant design in fields such as pressure equipment, aircraft structures and pipelines.
Method groups in this field
Static tests
Tension, compression, bending, shear and torsion. Yield and tensile strength, elongation and modulus of elasticity are obtained.
Impact tests
Charpy and Izod notch impact; the brittle-to-ductile transition behaviour of the material is determined as a function of temperature.
Hardness
Brinell, Vickers, Rockwell, Shore and micro hardness. Valuable for surface treatment depth and local differences in strength.
Fatigue
Force- and strain-controlled axial fatigue, fatigue in bending; S-N curves and the endurance limit.
Creep and stress relaxation
Behaviour under long-term load at high temperature; decisive for boiler, turbine and pressure equipment materials.
Fracture mechanics
Plane-strain fracture toughness, the J integral, CTOD and fatigue crack growth rate.
Wear and friction
Taber and rotating drum abrasion, coefficient of friction measurements.
Commonly confused in this field
- Calculating strength from hardness is approximate; it cannot be used as the sole evidence in material acceptance.
- Adequate static strength does not demonstrate fatigue strength; a cyclically loaded part requires a separate test.
- If test rate and temperature are not reported, the result cannot be compared — especially for polymers and composites.
- A test specimen and the actual part may not give the same value; moulding orientation, weld lines and differences in surface treatment all have an effect.
- A strength value given for a composite without stating the specimen orientation is meaningless.
- ASTM and ISO counterparts measure the same quantity but use different specimen geometries; the results are not treated as directly equivalent.
Which decisions these results support
- Design verification and material selection
- Incoming material control and supplier approval
- Meeting the mechanical requirements of the product standard
- Failure analysis, life prediction and damage tolerance calculation
- Verifying heat treatment and surface treatment processes
Related Tests
Frequently Asked Questions About Coefficient of Friction
According to which standard is Coefficient of Friction made?
Coefficient of Friction is executed in scope ISO 8295, ASTM D1894 and ISO 15359. The limit values and acceptance criteria to be applied are defined in the product standard; The version valid for your product is confirmed in writing at the offer stage.
Which products does Coefficient of Friction apply to?
Mainly applied to Plastic film and packaging, Coated paper and cardboard, Floor coverings and Automotive interior surfaces. Whether your product is included in the scope is determined by examining its technical specifications and intended use.
Under what conditions is Coefficient of Friction done?
The determining parameters are: Sled weight — Defined in the standard; typically 200 g in ISO 8295, Tensile speed — Constant rate per the standard; typically 100 mm/min and Contact pair — Defined as film-to-film or film-to-metal. The full terms are in the "Test Conditions" section on the page and vary depending on the product standard.
What kind of sample is needed for Coefficient of Friction?
The specimen must be flat, free of wrinkles and clean, The test surface (outer/inner) must be specified and Generally at least five measurements per set. The number of samples is determined according to the product standard and the scope to be reported.
How long does Coefficient of Friction take?
Duration per measurement is short; a set including conditioning is completed within half a working day. This duration belongs to the experiment itself; sample preparation, queuing and reporting are also evaluated. A realistic schedule for your product is given in the offer.
What is the Coefficient of Friction result called "appropriate"?
The acceptance criterion is given in the specification as a range for the static and dynamic coefficients of friction. Both a too-high and a too-low value can cause problems.