A dart impact test is a method to measure the impact resistance of plastic films and laminates by dropping a dart on them from a certain height. The test can help evaluate the quality, durability, and performance of various plastic products and materials. The test can also help compare the effectiveness of different surface treatments, such as electroplating, galvanizing, painting, etc. The test is standardized by several national and international standards, such as ASTM B117, ISO 9227, JIS Z 2371, and ASTM G85.
To perform a dart impact test on plastic films, you will need a dart impact tester, a sample holder, a scale, a release mechanism, and a sample of the material to be tested. You can find some examples of dart impact tester online, such as Presto Group or Amazon. You can also compare the prices, features, and specifications of different models and brands and choose the one that suits your needs and budget.
Here are some steps that you can follow to perform a dart impact test on plastic films:
1. Prepare the sample of the material to be tested according to the standards and specifications. The sample should be large enough to extend beyond the sample holder by at least 25 mm at all points. The sample should also be representative of the material under study and should be taken from the sheet or tube in such a manner that the whole of the sheet is represented in the test. You can use a template to guide the cutting of the sample and a thickness gauge to measure the thickness of the sample.
2. Clamp the sample in the sample holder and connect the pneumatic pipe to the vacuum pump. Turn on the vacuum pump to hold the sample securely and prevent any air pockets. The sample should be clamped by the specimen holder ring and should have a slit that allows the dart to pass through and tear the sample.
3. Adjust the level of the machine with the spirit level and lock the leveling bolts in the proper position. Ensure that the apparatus does not vibrate and has a proper earthing connection. Connect the power supply cord of the device to a 3-pin 5-ampere socket on a single-phase 230 V AC supply line.
4. Choose the appropriate weight of the dart that is nearest to the expected impact failure weight. You can also add the required number of incremental weights to the dart shaft and put the locking collar in its place to set the weights in a particular location.
5. Adjust the height of the drop of the dart according to the standards and application requirements. You can use the release mechanism of the vertical channel support to set the height of the drop. The dropping height of the dart can be 660 mm or 1524 mm, depending on the type of test.
6. Place the dart in the release mechanism and align it with the center of the sample. Make sure that the dart is free from any dirt or dust and has a smooth surface.
7. Release the dart from the starting position by using the trigger or the button of the release mechanism. The dart will fall freely and hit the sample, causing it to tear. The force and the distance of the tear will be recorded by the scale and the display of the device.
8. Remove the sample from the sample holder and examine the damage caused by the dart. You can use a marker to record the maximum force reached by the pointer and the scale. You can also use a ruler to measure the length of the tear.
9. Calculate the Falling dart impact tester of the material by using the formula: Dart impact strength = Weight of the dart in grams / 10 min. You can also use a computer interface or software to generate graphical and numerical reports of the test results.
10. Repeat the test with different samples and weights of the dart to obtain an average value of the dart impact strength of the material.
I hope this guide helps you to perform a dart impact test on plastic films.