Top-load testing (also known as 'column-crush' and 'axial force resistance') is performed mainly on blow moulded, thermoformed or injection moulded plastic containers. It measures the compressive strength of such containers to ensure they do not deform or break when subjected to axial forces during the processes of filling, closure, storage and transport.
There is an ever-increasing pressure to reduce the weight of plastics being used in packaging, but without compromising on strength and performance.
Top-load testing provides a standard method of obtaining data to set acceptance or rejection specifications for quality control, research and development and special designs.
It involves compressing filled or empty containers at a fixed speed until they yield at failure or deflect by a pre-set value. The maximum load applied is then recorded and compared against pass/fail criteria. When testing empty containers it is essential to allow air to be released from the container otherwise the accuracy and precision of measurements is adversely affected.
Top-load testers provide a reliable and accurate solution for meeting design standards and are often sited close to filling lines in production or nearby in the QC laboratory. They may also be applied for testing aluminium and steel cans, large cardboard boxes and plastic or metal drums.
Other variants of the top-load test include: Box crush (BCT), Edge crush (ECT), Ring crush (RCT).
