Coefficient of Friction Tester - COF Tester Overview
Friction and Slip Characteristics
Friction describes the resistance between two surfaces in contact, while slip refers to how easily they move against each other. A high coefficient of friction (COF) indicates low slip, while a low COF shows high slip. Plastic films, such as polyethylene, often use surface treatments or additives to enhance slip, although the effect can vary across the film.
Sample Preparation for Accurate COF Testing
Proper sample preparation is essential for accurate results. For plastic films, specimens should measure 250 mm x 130 mm for the plane and 120 mm square for the sled. Thicker materials should use 63.5 mm square samples. Specimens must be flat, wrinkle-free, and securely attached to ensure consistent results.
Conducting the COF Test
For static COF, start the drive mechanism and record the peak force needed to move the sled using the force gauge. For kinetic COF, measure the average force during continuous sliding. Once testing is complete, remove the samples and prepare the next set for testing.
Data Recording and Reporting
Data acquisition can be handled manually or through the FX-7200 Quality Control Software, which captures force vs. time graphs. Reports should include key details such as sample descriptions, test conditions, sampling rate, and thickness. Both static and kinetic COF values, along with standard deviations, must be included in the report.
Static COF is calculated by dividing the peak force by the sled weight, while kinetic COF is the average force during sliding divided by the sled weight. These unitless coefficients are reported in SI units. Qualitest offers both data forms and software compatible with Microsoft Excel™ for efficient data collection and reporting.
Qualitest COF Testers – ASTM D1894 and International Standards Compliant
The Qualitest FX-7000 and FX-7100 Friction COF Testers comply with the ASTM D1894 standard testing method for both static and kinetic friction. The FX-7000 is an analog tester with a fixed-speed test stand, while the FX-7100 features digital controls and enhanced functionality.
Models like the FX-7000-VS and FX-7100-VS offer variable-speed drives, and the FX-7100-VSC includes additional grips and a reversible drive for peel, seal, and low-elongation tensile testing.
Equipped with a 200-gram COF sled and certified weight specifications, all models ensure precision in friction testing. The FX-7200 Quality Control Software records data, creates graphs, and generates detailed reports.
