Top-Load testing

Test methods vary but all define the speed of compression and how far the package should be deformed. The peak force is typically recorded to determine the product's strength.

Since various standards call for deforming a container by a set distance, it is important that a top-load tester can accurately detect the initial height of the sample, and reliably move by the correct distance.

It is important that you take account of the test method when using data for comparative purposes, for example...

Vented vs non-vented plastic bottles
A top-load test of an empty plastic bottle using a non-vented method will trap air inside the bottle, causing a higher peak force value than a bottle tested using the vented method (that allows air to be released during the test). 

Cardboard container vs cardboard materials
For multi-wall cardboard materials it may be necessary to take a standard sample of the material rather than the whole container.

These samples are assessed for rigidity by Edge Crush testing held as being predictive of final construction strength.

Top-load (or Column-crush) testing ensures that packaging products consistently meet the requirements for resisting the axial load exerted during:

• Production
  Bottles, for example, must withstand the stresses of filling and capping.
• Storage and display
  Almost all packaging is stacked (palletized) at some point, in both empty and filled states. Top-load testing helps calculate how many pallets can be stacked during storage.
• Transport
  Extra stress is frequently experienced when packaging is subject to movement or when other products are placed on top. Packaging must be sufficiently robust to maintain integrity to industry standards when subject to these stresses.

Failure to meet these objectives can result in unacceptable levels of packaging failure which lead to:

• product leakage or total breakage for the consumer
• high product return rates for the manufacturer
• wastage and harmful environmental impact

In order to achieve optimum performance and meet corporate environmental-protection, manufacturers strive to “lightweight” or “down-gauge” packaging materials as far as possible while still ensuring that the package provides adequate product protection and is recyclable.

The down-gauging of billions of packaging products worldwide amounts to considerable cost savings by reducing the volume of raw materials but it places an extra onus on 'designing for strength'.

Plastic bottles and containers, cans, glass jars, or cardboard cartons, will all behave differently according to the materials used, the structural design of the container and, of course, its contents.

A common example of a stacked container is the plastic bottle, often made from HDPE or PET, and used globally as a container for beverages, oils, cleaning fluids and other liquids/gels. It has design features that affect axial load strength, including the closure, handles, grip areas, and the shoulder and base design. Some designs are made to improve nesting for unit-to-unit stacking and to increase stack stability.

As an example, the weight of the typical 500ml drinks bottle has been halved in the last 15 years, thanks to technologists..... but they couldn't have done it without Top-load testing !

 Use top-load testing as an integral part of the design process to ensure the most effective use of raw materials and for quality-control testing at your production line.