Peel Testing of Vacuum-Formed Containers

Custom Engineering Application

Semi-rigid thermoformed packaging, typically sealed with film or foil, is widely evaluated using the 45-degree peel method, as it closely replicates the way end users open such packs in real conditions. This method yields more representative and accurate peel strength figures than other approaches.

One of the major difficulties of testing these packages is the attachment of the sample without deformation, which can immediately affect the peel force measurement. The preservation of the initial shape of the pack during the test is essential for good repeatability.

In one application, a client required testing of food packaging trays with multiple cavities formed through thermoforming. To address this, Presto Stantest developed a customized fixture designed to hold the semi-flexible tray using vacuum support within a precisely matched recess. The fixture was aligned at 45 degrees to the testing column, enabling controlled and repeatable peeling from a defined corner of the lid.

The semi-rigid lid was gripped using a vice mechanism and connected to the force measuring system through a flexible linkage, simplifying sample handling and improving testing efficiency. The integration of vacuum-based holding ensures the secure positioning of samples while allowing operators to carry out peel tests quickly and with high repeatability.