Are you familar with latest national standard friction coefficient tester?
By measuring the smoothness of the material, it is possible to control and adjust the production quality process indicators of the material to meet the requirements of product use.
This test can also be used to measure the static and kinetic friction coefficient of rubber, cardboard, woven bags, fabric styles, metal material composite belts for communication cables, optical cables, conveyor belts, wood, coatings, brake pads, wipers, shoe materials, tires and other materials when sliding.
China national standard, equivalent to ISO 8295.
"GB/T 10006-2021 Plastics-Film and sheeting-Determination of the coefficient of friction".
1. Test principle
Put the two test surfaces flat together, under a certain contact pressure created by a sled. The two surfaces move srelative to each other, and the required force is recorded. Dividing the force value tested by the gravity of the sled is the friction coefficient value.
2. Test equipment
The test device consists of a horizontal test bench, a sled, a force measuring system and a driving mechanism that moves the two test surfaces on the horizontal test bench relative to each other. Sled or platforms can be used as moving parts.
Horizontal test bench should be smooth and non-magnetic metal material made.
normal force is generated by the sled, which should have a square bottom surface with an area of 40cm² (Side length 63mm), in order to evenly distribute the pressure, the bottom of the sled should be covered with elastic materials and it shall not avoid embossing the sample.The total mass of the slider shall be 200g±2g to produce a normal force of 1.96N±0.2N.
Drive structure shall be free of vibration, so that the two test surfaces are 100±10 mm/min is relatively moving. When there are special needs, the speed can be set 500±10 mm/min.
The entire force measuring system total error should not exceed 2%, the conversion time should not exceed 0.5S, and the traction direction should be parallel to the friction plane and on a straight line.
For measuring static friction, the elastic coefficient of the force measuring system should be adjusted to 2±1N/cm by appropriate springs. When measuring the kinetic friction force in the case of sliding and sticking, the spring is replaced by a rigid connection.
For each test, two samples with a size of 80×200mm are required. Samples shall be uniformly intercepted in 3 groups throughout the width or circumference of the sample.
Generally, the length direction of the sample (I. e. the test direction) should be parallel to the longitudinal direction of the sample (machining direction). If the friction properties on the front and back of the sample or in different directions are different, tests should be carried out separately.
4. Status adjustment
Unless otherwise specified, the film sample shall be adjusted for at least 16 hours before testing in accordance with the 23/50 standard environment in ISO 291. The test was conducted in the same environment.
5. Test procedure
5.1 Film to film
The right end of the first sample is fixed on the test platform with double-sided adhesive tape, and the long axis of the sample is consistent with the platform.
Use double-sided tape to attach a small plate to the left end of the second sample and reinforce it. The mass of this small board should not exceed 5g. This small plate is connected to the sensor by a spring. Place the second sample on top of the first sample and place the slider gently on top of the sample without vibration so that both the second sample and the slider are in the center of the first sample.
15s later, start the test platform and recorder. The first peak of the force value is generated as static friction.
After the first vertical peak, force oscillations may sometimes occur. In this case, the oscillating part of the curve cannot be used to evaluate the dynamic friction coefficient. The dynamic friction coefficient should be measured separately to prevent slippage by replacing the spring with a rigid connection. Due to inertia error, this test cannot be used to evaluate static friction.
The sensor is directly connected to the sled, the second sample is fixed at the front edge of the slider with double-sided tape. This method is not recommended for harder specimens because bending moments may cause uneven pressure distribution.
5.2 Film to metal or other articles
When measuring the friction performance of plastic film (sheet) on the surface of other materials, the samples of other materials are fixed on the horizontal test bench. Other test
steps are the same as above.
6. Result calculation
6.1 Static friction coefficient
straight rise represents static friction.
μs = static friction fS/normal force fP
6.2. Kinetic friction coefficient
Kinetic friction fD starts from the relative movement between the two contact surfaces, regardless of the static friction peak F.S.
μD = kinetic friction FD/normal force fP