Test of friction coefficient of the hottest flexib

Test of friction coefficient of flexible plastic packaging materials

the test of friction coefficient of flexible plastic packaging materials can control and adjust the opening of packaging bags, the packaging speed of packaging machines and other production quality process indicators. The friction coefficient test is suitable for non viscous plastic films and thin sheets with a thickness of less than 0.2. The test methods are discussed as follows

independently complete the setting of experimental parameters, the control of experimental process, data collection, processing, analysis and display

1 sample and its preparation

1.1 sample size

1.1.1 each measurement generally requires two 8cm × 20cm sample

1.1.2 if the sample is thick or rigid, and double-sided tape must be used to fix it to the slider, the size of a sample should be the same as the bottom size of the slider (60mm × 63mm)

2.2 cutting of samples

samples should be cut evenly across the entire width or circumference of the sample (when the pipe film)

2.3 face and direction of the sample

if the friction properties of the front and back sides of the sample or different directions are different, the test should be carried out separately. Generally, the length direction (i.e. test direction) of the sample should be parallel to the longitudinal direction (machining direction) of the sample

2.4 requirements for samples and test surfaces

2.4.1 the samples should be flat, free of wrinkles and scars that may change the friction properties. The edge of the sample should be smooth

2.4.2 the test surface of the sample shall be free of dust, fingerprints and any foreign substances that may change the surface properties

2.5 number of samples, at least three pairs of samples shall be measured for each test. If higher test accuracy is required, the number of samples can be increased

3 condition adjustment of the sample and standard environment of the test

condition adjustment of the sample shall be carried out for at least 16h in a standard environment with a temperature of 23 ± 21 ° C and a relative humidity of 45%-55%. Then carry out the test under the same environment

4 test steps (equipment electronic tensile machine ldm-100, Beijing landmark)

4.1 determination of film (sheet) to film (sheet)

4.1.1 put the test surface of a sample upward and fix it flatly on the horizontal test bench. The length direction of the specimen and the test bench shall be parallel

4.1.2 put the test surface of another sample downward, wrap the slider, and fix the sample on the front and upper surface of the slider with adhesive tape

4.1.3 if the specimen is thick or rigid, which may produce bending moment and uneven pressure distribution, 63mm specified in 1.1.2 should be used × 63mm specimen. Between the bottom surface of the slide block and the test piece is not 3. Sheet metal: it is the surface of the fatigue testing machine. A kind of protective layer is used to fix the test piece with double-sided tape

4.1.4 place the slider fixed with the sample in the center of the first sample without impact, and make the test direction of the two samples parallel to the sliding direction, and the force measuring system is just not under force

then start the test

after the two samples are kept in contact for 15s, the two samples move relatively, and the first peak of the force is the static friction FS

the average value of the force within 6cm of the relative movement of the two samples (excluding static friction) is dynamic friction FD. This process is automatic control

4.1.5 during the test, if the force value oscillates after the static friction, the dynamic friction cannot be measured. At this time, the spring between the slider and the load sensor should be canceled, and the dynamic friction should be measured separately. Due to inertia error, this measurement is not applicable to static friction

4.1.6 when the friction coefficient of the measured object is less than 0.006, it is recommended to use the 500g slider configured by Beijing landmark equipment for accuracy

5 test results show that

5.1 static friction coefficient

static friction coefficient is calculated by formula (2):

formula: μ S - static friction coefficient

fs - static friction, N

fp -- normal force, n

5.2 dynamic friction coefficient

dynamic friction coefficient is calculated by formula (3)

where: μ D - dynamic friction coefficient

fd - dynamic friction, N

fp - normal force, n

5.3 friction coefficient instrument connection software, print the test report as follows

where the static standard deviation δ s. Dynamic standard deviation δ D represents the confidence of static and dynamic friction coefficient respectively,

us confidence = (1- δ s） × 10%

ud credibility = (1- δ d） × 100%

effectively judge the accuracy of the test data of this group, and it must be ensured that two tests at the same time with us and UD above are meaningful

in the composite flexible packaging industry, the dynamic and static friction coefficient of the inner bag is generally required to be small and 0.3. For the manufacturers of film packaging materials, the rest of the company's business can control the friction coefficient by testing the opening agent, smoothing agent, type and content in the resin to meet the user's requirements