ASTM D4168 Standard Test Methods for Transmitted Shock Characteristics of Foam-in-Place Cushioning Materials
The purpose of ASTM D4168 is to determine how well foam-in-place packaging materials are shock-absorbing. There are two test methods proposed for this standard. They are:
- Test Method A: free-fall package drop test apparatus
- Test Method B: shock-test apparatus
Either of these methods can be used. However, it is important to note that they will not necessarily provide the same results. The tests will measure the accelerations that are transmitted to a test block when the package is subjected to drops or shocks. The test is useful in determining the protective capability of foam-in-place packaging material. The method includes using plastic film, the foam, and the box that is usually used for packaging.
It is very important that all the data regarding the physical test specimen is recorded. Samples need to be of a representative quality so that it will be an indication of field performance. It is recommended that the samples be allowed to rest for a minimum of 24 hours before testing. This allows the foam to have an opportunity to cure and stabilize after being poured into the packaging.
To prepare the test specimen:
- Modified Free-Rise Bottom Cushion Fabrication- the foam should be dispensed into the bottom of the box then place the barrier film over the foam and position the test block so that the foam will rise. It is important to make sure that the foam is dispensed in a fashion that will allow it to be representative of actual packaging. It should not be overly dense or have any large voids.
- Premolded bottom Cushion Fabrication- the foam can be molded outside of the container with a block that will provide the correct dimensions. Again, make sure that the proper amount of foam is dispensed so that it is not too dense and does not have large voids.
The test machines must be set up in accordance with ASTM D4168 standards. The package should be conditioned prior to testing. They should be conditioned long enough to reach equilibrium. Prepare the test specimen and reach the desired static load. Next, insert the cushion into the container and place the test block into the cavity. Add the top cushion and the package is ready for testing. Test the sample(s) by following the guidelines of ASTM D4168. Conclude testing by calculating drop height, static loading, and density. It is important to keep accurate measurements throughout the test so that it can all be included in the report. The testing laboratory will compile a report that details the results of the test. This report will follow the guidelines laid out in the ASTM standard.
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