Film is used in many different ways in modern life. Depending on what it does, the film can be water-proof, rust-proof, heat-shrinkable, flexible, oxygen-proof, heat-resistant, etc. Depending on how the film is made, it can be wrapped with extrusion blow molding, extrusion casting, calendaring, solution casting, one-way and two-way drawing, CO extrusion composite, coating film, etc.
Different ways of making things, different kinds of making tools, and how good the people who use them are will all affect the quality of the final product. So, the quality of finished products should be tested to see how well quality and cost are being controlled. Because of this, the film dart impact tester is a great piece of equipment that film manufacturers can use to improve the impact strength of film falling standards.
Test principle of free-falling dart method
At the start of the experiment, the first choice is the experimental method and measuring the initial quality and Δ M value. The experiment is then performed. If a sample is broken, you can lower the falling mass by adding a weight of Δ M. If a sample doesn’t break, a weight must be used, and the falling mass must be added to the weight. The experiment should then be done based on this information.
In short, adding or taking away weights depends on whether or not the previous sample is damaged. After taking 20 samples for the experiment, figure out the total number of damages. If n equals 10, then the experiment is over. If n is less than 10, the experiment will keep going until n is equal to 10; if n is more than 10, the experiment will keep going until the total number of undamaged is equal to 10, and then the system will automatically calculate the impact results.
Application of the falling dart impact tester
One of the most common ways to package laundry detergent is in soft plastic composite film bags. These bags can be made of PET/PA/PE, PET/PA/Al/PE, etc. Compared to other products, the unit package of washing liquid usually has a large weight. So that bags don’t break as they move around, the materials used to package washing liquid must be very strong when hit.
At the moment, the free dart method and the pendulum impact method are used to test how well flexible plastic packaging materials can take a hit. In the first method, the impact resistance of the material is measured by how much a dart weighs when it breaks through the film. In the second method, the impact resistance of the material is measured by how much energy the dart loses when it breaks through the film. The free dart method can be used to test detergent packaging because it is usually thick and has a high resistance to being hit.
It’s one of the most important things to test the impact resistance of a flexible packaging machine, which can show how well the packaging machine can handle impacts. It’s easy to see how well the packaging machine can take a hit.
It can be used to test the impact resistance of plastic film, sheet, and composite film with a thickness of less than 1 mm, such as PE fresh-keeping film, winding film, PET sheet, food packaging bags with different structures, aluminum foil, aluminum plastic composite film, etc.
It can be used to test how well paper and paperboard hold up when hit. It can be used for the sample’s drop ball impact test and shoulder liner impact test.
How to use a falling dart impact tester?
Take a film of a certain size and place it on the instrument. Raise a falling dart of a certain quality to a certain height and place it right in the middle of the film. Let go of the falling dart and let it hit the film freely, then look at the damage. By changing the weight of the dart over and over, the critical mass of the film when it is hit is found. Then, the amount of energy needed to hit the sample is calculated.
Measurement method: method A is applicable to materials with impact damage mass of 50-2000g and impact height of 660mm; Method B is applicable to materials with impact damage mass of 300-2000g and impact height of 1500mm.
- Select test method
After startup, click “method A” on the instrument control panel to change to method a test, and then click “method B” to change back to method B.
- Enter initial mass
Before the experiment, it is important to find out how much the dart head weighs and how much damage it will do to the film. Then, use the estimated damage mass as the initial mass.
Pressing the “initial quality” key on the control panel will bring up a box. Press the corresponding number keys to enter the initial quality value, and then press the “confirm” key again to confirm.
On the screen, the initial mass and the current mass will be shown. Before the first collision, the mass was the same as it is now.
- Input change quality
The change mass is the amount of mass that needs to be added when the dart head impact sample is broken during the experiment and the amount of mass that needs to be taken away when the sample is not broken.
To change the quality, press the “change quality” key on the control panel to bring up a box, then press the corresponding number key to enter the change quality value, and then press the “confirm” key again to confirm.
The quality that has been changed will be shown on the screen. Once the quality of the change is known, it won’t change during this experiment.
- Clamping sample
Press the “sample clamping” key to open the sample holder, place the sample in the middle of the sample holder, and then press the “sample clamping” key to close the sample holder and clamp the sample. The sample shall be tightened without wrinkles after clamping.
- Clip dart head
First, add a suitable weight to the dart head so that its total weight is the initial mass input in front, and then tighten the weight.
The instrument provides 30mm and 45mm diameter weights. 30mm diameter weights are used for method A and 45mm diameter weights are used for method B. The weight of the weight is engraved on the weight.
Press the “start” key once, and then insert the end of the dart head into the hole under the dart head fixing device from below. The dart head will be automatically fixed into the dart head fixing device.
Press “start” on the control panel again to release the dart head and make the dart head fall freely to impact the sample.
Observe the impacted sample.
If the sample breaks after being impacted, press the “break” key;
If it is not broken, press the “not broken” key;
If the dart head fails to successfully impact the sample for special reasons, the test results need not be recorded.
After the button is pressed, the display screen will change accordingly:
After pressing “break”, the current mass will decrease by the value of the changing mass (15g by default) on the basis of the initial mass, and a solid point will appear at the corresponding position in the coordinate diagram of the display screen;
After pressing “not broken,” the current mass will add a value of changing mass on the basis of the initial mass, and a hollow point will appear at the corresponding position in the coordinate diagram of the display screen.
- Impact again
Change another sample clamp as described above.
Add or subtract the weight according to the value of the current mass on the display screen, and then insert the end of the dart head into the hole under the dart head fixing device from below, and the dart head will be automatically fixed into the dart head fixing device.
Press “start” again to release the dart head, so that the dart head can make a free fall and impact the sample.
Take a look at the impacted sample and choose “damaged” or “not broken” based on how the sample looks.
- Multiple impact
Repeat the test as described in 7) above. After 20 tests, calculate the number of damage n. If n is equal to 10, the test is completed. If n is not equal to 10, the test continues until the number of damage and failure reaches 10.
If all the first 10 tests before the start of the test are not broken, it indicates that the value of the estimated damaged mass in 2) above is too small, and this test fails. It is necessary to re estimate the value of the damaged mass and return to step 2 to continue the test.
If all the first 10 tests before the start of the test are damaged, it means that the value of the estimated damaged mass in 2) above is too large, and this test fails. It is necessary to re-estimate the value of the damaged mass and return to step 2 to continue the test.
- Experimental results
When the number of times of damage and the number of times of failure are greater than 10, press “calculate,” and the value displayed by the damage quality is the experimental result.
If you need to print the report, press “print” to output the print report.
Note: if there is no response after pressing “print,” you can check whether the printer is short of paper.
If you need to test another sample, you can press “reset” at this time, and all the parameters of the instrument will return to their initial setting.
At the end of the experiment, turn off the compressed air and power supply.
- Do method A and method B both give the same results?
Inconsistent. Method A and Method B both use the same unit and are based on the same test principle. But because the test subjects were different heights and weights, the test results can’t be compared at all. At the moment, method A is much better than method B when the dart impact testing machine is used in the experiment.
- How to fix the film dart impact tester‘s most common problems?
The film dart impact tester is a very accurate tool for testing. During use, you might run into some problems, so how do you fix them?
1) The display screen does not light up after power on
Check whether the external circuit is normal and whether the safety tube at the switch is intact. Check whether the power cord is damaged and replace it. Check whether the data connection line is normal.
2) The display screen is garbled or white
Cut off the power supply and re supply the power. Check whether the circuit has overvoltage or insufficient voltage. In case of disoperation, the white screen will also appear. Please contact us.
3) Print no response
When the indicator light flashes, it indicates that the printing paper is used up and needs to be replaced; if the indicator light is not on, it indicates that the circuit is faulty. Check that the power is turned on.
4) Falling darts can’t absorb
Check whether the data cable is connected normally, check the electromagnetic state, and if the weight is overweight.
5) Foot switch inoperative
Whether the data cable is correctly connected. Examine the foot switch for damage. Check whether the data cable is connected normally.
6) Adjustment of dart dropping Center
The center of the falling dart can be moved with a heavy hammer when the instrument is first set up or when the falling dart is not in the middle of the test.
Put the marked side of the cover plate up, cover it with the upper fixture, turn on the electromagnetic, hold the black short rod in the test position with the bottom end of the heavy hammer facing down, look at the difference between the mark and the mark after it is still, and adjust the four leveling anchors at the bottom end to line up the weight with the mark in the middle of the cover plate. After adjusting it, clamp the test sample.