A dynamic coefficient of friction test report documents the laboratory-measured sliding resistance between two surfaces under strictly controlled conditions, expressed as the dimensionless ratio of friction force to normal force. Testing is performed by accredited third-party laboratories in accordance with internationally recognized standards such as ISO 8295, ASTM D1894, GB/T 10006, EN 13893 and ANSI A137.1, covering plastic films, flooring, rubber, paper and coated materials. This article explains the technical basis of the test, how a compliant report is structured, and how the results should be interpreted for quality control and product safety decisions.
Technical Overview
The dynamic coefficient of friction (DCOF, also called kinetic COF, symbol μd or μk) is defined as the ratio between the tangential force required to sustain sliding of one surface against another and the normal force pressing the two surfaces together. It is calculated from the force measured after motion has been initiated, averaged over the steady sliding portion of the force–displacement curve. The governing expression is μd = Fd / N, where Fd is the mean kinetic friction force and N is the normal force, typically the weight of the sled assembly.
Dynamic COF differs fundamentally from static COF, which is derived from the peak force at the instant sliding begins. Static friction governs whether an object starts to move, while dynamic friction governs how it continues to move. This distinction is critical in practice: a packaging film must slide smoothly over stainless-steel guide rails of a form-fill-seal machine, a floor tile must provide predictable wet slip resistance under a walking pedestrian, and a sheet of paper must feed reliably through high-speed printing equipment. A dynamic coefficient of friction test report provides traceable, quantitative evidence of these sliding behaviors.
Because friction is a system property rather than an intrinsic material property, the reported value is meaningful only together with the full test conditions: the mating surface pair, sled mass, contact area, sliding speed, temperature, humidity and specimen orientation. A professional test report issued by an accredited third-party laboratory therefore records all of these parameters, in line with the general requirements of ISO/IEC 17025 for testing laboratories.
- ISO 8295 and GB/T 10006 — plastics film and sheeting, determination of coefficients of friction by the horizontal plane method
- ASTM D1894 — static and kinetic coefficients of friction of plastic film and sheeting
- ISO 15359 and ASTM D4917 — paper and board, static and kinetic coefficient of friction, horizontal plane method
- EN 13893 — resilient, laminate and textile floor coverings, determination of dynamic coefficient of friction
- ANSI A137.1 (DCOF AcuTest) — wet dynamic coefficient of friction of ceramic tile
- ASTM D2047 — static coefficient of friction of polish-coated flooring using the James machine (complementary method)
- ISO 15113 — rubber, determination of frictional properties
Testing Samples
Plastic Films, Sheets and Laminates
Flexible packaging materials are the most frequently tested category, including polyethylene (PE), polypropylene (PP), cast and oriented films, PET, coextruded structures, metallized films and multilayer laminates. Specimens are typically supplied as flat sheets or roll samples free of creases, folds and surface contamination. Test strips are cut in both the machine direction (MD) and transverse direction (TD), and both the treated and untreated sides may be evaluated. Common test pairings are film-to-film, which simulates bag stacking and nesting, and film-to-stainless steel, which simulates movement over packaging machine surfaces.
Flooring and Hard Surface Materials
Ceramic and porcelain tiles, luxury vinyl tile (LVT), laminate flooring, resilient sheet goods, rubber flooring and polished natural stone are tested to characterize pedestrian slip resistance. Specimens are typically supplied as full tiles or cut panels with clean, flat, unworn surfaces. Depending on the referenced standard, tests may be performed in the dry condition or in the wet condition using a standardized surfactant solution to represent realistic service environments.
Rubber and Elastomeric Products
Seals, gaskets, conveyor belting, footwear soling compounds, tire tread materials and elastomeric sheets are tested to characterize sliding behavior against counter-surface materials such as steel, glass or polymer plates. Specimens are usually die-cut flat plaques with uniform thickness, and the counter-surface material is specified by the client or by the product specification.
Paper, Board and Converted Products
Printing papers, carton board, labels, release liners and coated papers are evaluated to ensure reliable feeding, stacking and transport through converting and printing equipment. Tests are performed in both MD and TD directions, and separate determinations may be made for the wire side and felt side of the sheet.
Coated, Printed and Specialty Materials
Printed films, varnished or lacquered surfaces, painted metal panels, textiles and nonwoven liners can also be characterized. For these materials, the laboratory works with the client to define the mating surface, normal load and sliding speed that best represent the intended application.
Testing Items
The core deliverable of the engagement is the dynamic coefficient of friction value, but a complete test program typically includes the following items:
- Dynamic (kinetic) coefficient of friction μd — the primary reported result
- Static coefficient of friction μs — determined from the initial force peak in the same test run where the applied standard permits
- Multiple surface pairings — for example film-to-film, film-to-stainless steel, flooring-to-rubber slider in dry and wet states
- Directional testing — machine direction and transverse direction, and side A versus side B for films
- Stick-slip behavior — qualitative or quantitative observation of intermittent, jerky sliding, which is often as important as the mean value itself
- Aging studies (optional) — repeat measurements after defined storage periods to track the time-dependent migration of slip additives such as erucamide in polyolefin films
Each determination is repeated on fresh contact areas, with a minimum of five replicate measurements per condition being customary, and the report presents individual values together with the arithmetic mean and standard deviation.
Testing Methods
Test Principle and Apparatus
The predominant technique is the horizontal plane method. A specimen is fixed to a flat, level test table and a second specimen is wrapped around the base of a sled of defined mass and contact geometry. The sled is connected through a low-friction link to a force transducer mounted on a driven carriage. As the carriage moves at constant speed, the force required to drag the sled is recorded continuously. Film testing instruments per ASTM D1894 commonly use a 200 g sled with a 63.5 mm square base and a sliding speed of 150 mm/min, while ISO 8295 and GB/T 10006 specify a sliding speed of 100 mm/min. For flooring, dedicated tribometers with standardized rubber sliders and wetting solutions are used under EN 13893 and the ANSI A137.1 DCOF AcuTest procedure.
Specimen Preparation and Conditioning
Specimens are conditioned to equilibrium in a standard laboratory atmosphere of 23 °C ± 2 °C and 50 % ± 5 % relative humidity in accordance with ISO 291 or ASTM D618, typically for a minimum of 24 hours and in many film programs for at least 40 hours. Specimens are handled with clean gloves or tweezers to prevent contamination of the contact surfaces, which can measurably alter the result. The orientation of each specimen, the identity of the contacting surfaces and the direction of sliding relative to MD or TD are documented for every determination.
Test Procedure
- Secure the plane specimen to the test table, ensuring it is flat, wrinkle-free and firmly adhered without tape entering the sliding path.
- Wrap the sled specimen around the sled base and fix it so that only the test surface is exposed.
- Place the sled gently onto the plane specimen, align it with the direction of motion and connect it to the force transducer.
- Start the drive and pull the sled at the constant speed specified by the standard over the required sliding distance.
- Record the complete force–displacement curve, noting the initial peak force (static) and the mean force during sustained sliding (kinetic).
- Repeat the measurement on fresh, previously unused contact areas for the required number of replicates, typically no fewer than five.
Calculation and Data Reduction
The static and dynamic coefficients are computed as μs = Fs / N and μd = Fd / N, where Fs is the peak force at the onset of sliding, Fd is the average force over the defined steady sliding interval, and N is the normal force corresponding to the total weight acting on the contact interface. Where stick-slip oscillation occurs, the standard-specific rules for averaging, such as using the mean of the oscillating force trace, are applied and the behavior is noted in the report. Results are reported to two decimal places together with the mean and standard deviation of the replicate set.
Report Contents
A compliant dynamic coefficient of friction test report issued under an ISO/IEC 17025 accreditation includes, at minimum, the following elements:
- Laboratory identification, accreditation scope reference, unique report number and pagination
- Client details and sample identification, description and condition as received
- Date of sample receipt, date of conditioning and date of testing
- Complete identification of the test standards applied and any deviations from them
- Description of the apparatus, sled mass, contact geometry, sliding speed and calibration status
- Conditioning parameters and the temperature and humidity recorded during testing
- Specimen orientation, surface pairing and sliding direction for every determination
- Individual measured values, arithmetic mean and standard deviation
- Observations such as stick-slip behavior, surface damage or transfer
- A statement of conformity against specified limits when requested, together with the decision rule applied
- Identification of the responsible signatory and the date of issue
Applications
Dynamic coefficient of friction data support a wide range of engineering, quality-control and regulatory purposes across many industries:
- Flexible packaging development — optimizing slip and anti-block additive levels so that bags, pouches and films run reliably on vertical and horizontal form-fill-seal lines, printing presses and bag-making equipment
- Walkway safety compliance — demonstrating that ceramic tile, vinyl, laminate and stone surfaces meet wet or dry dynamic friction thresholds referenced in building specifications and accessibility guidelines
- Incoming inspection and supplier qualification — verifying that received film, board or rubber lots conform to agreed friction specifications before production release
- Material and formulation development — comparing polymer grades, surface treatments, coatings and corona or plasma treatment levels during product design
- Aging and shelf-life studies — tracking the post-extrusion migration of slip agents in polyolefin films to select optimal additive loading and confirm performance throughout the intended shelf life
- Forensic and failure analysis — investigating slipping accidents, packaging line stoppages, feeding faults and handling complaints using measured friction evidence
- Automotive, medical and electronics applications — characterizing seals, membranes, sterile barrier materials, liners and component handling surfaces
Typical acceptance guidance includes wet DCOF values of at least 0.42 for level interior ceramic tile floors per ANSI A137.1, dynamic COF of at least 0.30 in the dry condition per EN 13893 for many floor covering applications, and customer-specified film-to-steel ranges commonly between 0.20 and 0.35 for machine-running surfaces, although every specification must always be agreed against the actual product standard or purchase contract.
FAQ
What is the difference between static and dynamic coefficient of friction?
Static COF describes the resistance at the moment sliding starts and is calculated from the initial peak force, whereas dynamic COF describes the resistance while sliding is already in progress and is calculated from the averaged steady-state force. In many materials the static value is higher than the dynamic value, and both are frequently obtained from the same test run and presented side by side in one report.
Which standard applies to my product?
Plastic films and sheeting are usually tested to ISO 8295, GB/T 10006 or ASTM D1894; paper and board to ISO 15359 or ASTM D4917; rubber to ISO 15113; and floor coverings to EN 13893 or the ANSI A137.1 DCOF AcuTest depending on the market and specification. The correct choice depends on the product type, the intended mating surface and the jurisdiction of the specification, and an accredited third-party laboratory can confirm the applicable method before testing begins.
What sample size and quantity should I submit?
For film testing, flat samples of approximately A4 size or larger, free of creases and contamination, are generally sufficient for both surfaces and both orientations with full replication. For flooring, three to five full-size tiles or equivalent cut panels are customary. The laboratory should always be consulted in advance, since required quantities increase when multiple surface pairings, wet testing or aging studies are included.
What dynamic COF value is considered acceptable?
There is no universal pass or fail limit because acceptance depends on the product specification. Wet flooring thresholds such as 0.42 in ANSI A137.1 and dry thresholds such as 0.30 in EN 13893 are common regulatory references, while packaging film limits are typically set bilaterally between supplier and converter based on machine trials. The report can include a conformity statement against any limit defined by the client.
Why can results vary between tests or laboratories?
Friction is highly sensitive to surface condition, temperature, humidity, sliding speed, normal load and specimen history, including the migration behavior of slip additives over time. Small differences in conditioning, handling or instrumentation can shift results by several hundredths. This is precisely why standards prescribe controlled atmospheres, defined sled geometry and fixed speeds, and why results should only be compared when the documented test conditions are equivalent.
How long does the test take?
The mechanical measurement itself takes only minutes per replicate, but a complete program including conditioning at 23 °C and 50 % relative humidity, multiple replicates, data evaluation and report issuance typically requires three to seven working days from acceptance of the samples, with aging studies extending over the defined storage periods.
Can the report be used for certification and regulatory purposes?
Yes, when the testing is performed by an accredited third-party laboratory operating under an ISO/IEC 17025 quality management system, the report carries the traceability, impartiality and documented methodology required for supplier audits, tender submissions, regulatory demonstrations and dispute resolution, provided the selected standard matches the applicable product specification.