Testing Resistance of Plastic Sheet to Free Falling Impact
Plastic sheets are manufactured based upon its various uses and applications. Their thickness, durability, tensile strength and impact resistance all are set as per the use. Their physical properties and chemical properties both are fixed as per its use. For instance a plastic material used for packing a ball may not require that much of resistance against pressure as it is already wrapped around the ball and have not empty stretched place where a free falling impact can generate damages. However, a plastic material used for packaging a ready-to-eat food content requires high amount of impact resistance as it is stretched and sealed to block the entry of humidity or moisture content inside and damage the product.
To differentiate between the materials and set a proper impact resistant value for them, equipments like Dart Impact Tester
is required. This testing machine is capable of testing the impact of a free-falling dart of a stretched plastic sheet or film. The test results is done by visual inspection but the amount of load fallen on the specimen with what amount of speed and number of falls can be digitally recorded. Also to make the fall accurate and same for ever fall cycle, precision based features like electromagnetic dart holder is used. A digital based counter is installed which keeps a record of number of falls have been used to rupture the film.
For instance, a plastic sheet ‘A’ which is to be tested is examined for 10 dart falling cycles and is still not ruptured and on the other hand the Plastic film ‘B’ is ruptured on the third round. Based on the requirement, the plastic sheet A or B is used. Is the application requires tough resistance, then A is chosen and if it doesn’t require much of strength then may be B material would be selected for further processing.
The electromagnetic release and hold mechanism is specially designed to perform an error free testing. The holding of the dart at a particular height and holding it still prior the fall add to precision of testing, which a human can never perform. And afterwards, the release of dart at a specified speed can only be done using electromagnetic forces. The dart which is selected for impact test ranges in weight. There are options of distinct weight for dart heads. It can be chosen as per the test requirement.
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