comes in many shapes and is made from a variety of materials depending on the product it is designed to protect. That may include bottles for beverages, sealed bags to keep food fresh, or biomedical packaging designed to keep a product sterile. To determine whether or not the packaging
is able to perform the desired function each packaging type requires an array of material tests.
Water, soda, and juice bottles, for example, come in a variety of shapes and sizes and are subjected to a range of material tests such as structural rigidity to make certain they won’t rupture when filled or fold over when stacked and a burst tested to determine at which the point the bottle fails when filled with fluid.
To make sure that bottles will go through production lines without jamming dimensional measurements such as height are done. Wall thickness dimensions are taken at various points to ensure consistency for structural integrity. As bottles are often stacked on top of each other and shipped on pallets, a top-load test is required to test rigidity and determine if the bottle is able to withstand stacking forces.
These tests are typically conducted by a digital force tester
configured 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 low enough to just touch the top of the bottle.
The next stage compresses
the bottle down to a programmed displacement point where a force reading is taken. Initial bottle height and force at that displacement point must fall within a tolerance range defined by the quality department to assure the users that the bottles perform the desired function for the fluid they hold.
The seals used on packaging
for foods such as yogurt, cookies, potato chips and cereal, are extensively tested to ensure their proper performance. These seals may be adhered together or pressure sealed.
How often has someone had a snack bag rip open instead of the seal, leaving the food to fall out of the bag. This happens when the seal is much stronger than the bag material that is sealed together. Peel testing
is done by pulling apart the seals to determine the strength of the seal. The testing generates valuable information for determining the bag’s structural integrity when forces are applied.
There are different types of peel tests
and a variety of results that require a testing system such as a Lloyd LS1 testing machine
. A common test is to cut a strip one inch wide and four inches long with the seal in the middle, commonly called a T-Peel. The ends are placed in the grips for the specimen to be pulled apart at a pre-Programmed test speed so that the material is uniformly pulled apart. Common results include Maximum Force and Average Peel, which in some cases is called Peel Strength
or Seal Strength.
To check the integrity of the entire bag burst strength testing is done. The sealed bag is compressed between two plates to record the maximum force prior to bursting. This test helps ensure that the chips remain fresh and aren’t broken when force is applied when the bags are stacked or packed together.
These are just a few examples of the material tests done on packaging
to protect the packaged product, to maintain its freshness, or determine the “use-by” date commonly stamped on the package.