Packaging is available in a whole range of shapes and sizes and is comprised of various materials depending on what kind of product the packaging is designed to protect. Common packaging types include sealed bags designed to keep food fresh, bottles for beverages or biomedical packaging developed to ensure sterility.
Packaging Testing with the Lloyd Material Tester
In order to ascertain whether or not the packaging at hand can perform the desired function, each packaging type may need to be subjected to a selection of material tests.
For example, water, juice and soda bottles come in a range of shapes and sizes, so these are subjected to varied material tests like structural rigidity to ensure that they will not rupture when filled, or fold over when they are stacked. They may also be subjected to a burst test to ascertain at which point the bottle will fail when filled with fluid.
Methods for Package Testing
In order to ensure that bottles can pass through production lines without jamming, dimensional measurements like height are conducted. Wall thickness dimensions will be taken at different points to confirm consistent structural integrity. As bottles are generally stacked on top of each other before being shipped on pallets, a top-load test is needed to test for rigidity, ensuring that the bottle can withstand such packing forces.
A digital force tester is generally used to conduct these tests. It will be fitted with compression plates that apply a force to the top of the bottle. The height of the bottle can be taken by programming the tester to move its crosshead down to a force that is low enough to just touch the top of the bottle.
After this initial stage, the bottle is compressed down to a programmed displacement point where a force reading is undertaken. Initial bottle height and force at that particular displacement point should be within a tolerance range that has been defined by the quality department in order to make sure that the bottle performs the desired function for the liquid that it holds.
Seals used on the packaging for foods like cookies, potato chips, cereal and yogurt are tested comprehensively to guarantee proper performance. These seals may be pressure sealed or adhered together.
Snack bags often rip open instead of the seal, causing the food to fall out of the bag. This occurs because the seal is far stronger than the material of the bag that is sealed together, so to avoid this, peel testing is undertaken by pulling apart the seals to determine their strength. Such testing provides valuable information used for determining the bag’s structural integrity when forces are applied to it.
There are various forms of peel tests and a range of results which need a testing system such as a Lloyd LS1 testing machine. A routine test is to cut a strip that is one inch wide and four inches long with the seal in the center. This is commonly known as a T-Peel.
The ends of the T-Peel are placed in grips and the specimen is pulled apart at a pre-programmed test speed so that the material is pulled apart uniformly. Common results include Average Peel (sometimes known as Seal Strength or Peel Strength) and Maximum Force.
Burst Strength Test
In order to check integrity of the whole bag, burst strength testing is undertaken. The sealed bag is compressed between two plates in order to record the maximum force before the bag bursts. Undertaking this specific test helps make sure that the food products in the bag remain fresh and are not damaged as force is applied when bags are packed together or stacked.
Of course, these are just some examples of the material tests applied to packaging in order to protect the products being packaged. These tests can help make sure the product maintains its freshness, and often dictate the ‘use by’ day that is commonly included on packaging.
This information has been sourced, reviewed and adapted from materials provided by Lloyd Instruments Ltd.
For more information on this source, please visit Lloyd Instruments Ltd.