Why is it Important to Test Tensile Strength of Seals

In order to understand the importance of tensile testing to determine impulse sealer seal strength, it is necessary to know just what tensile testing is and what the resulting data of such a test indicates.test tensile seal strength

Essentially, this type of test determines how a particular material, bond, etc. reacts when force under tension is applied to it – in other words, when it is being pulled apart.

One of the most commonly used and simplest mechanical tests, tensile testing measures the amount of force required to elongate specific materials to breaking point and subsequently determines material properties quality control managers and/ or designers can use to predict how a material will perform in its intended application.


While some industries require highly advanced, complicatedmachinery for tensile testing, peel testing of packaging materials/ impulse sealer seal strength can be performed using compact devices specifically designed for this purpose. Easy to use via a simple control panel, these devices come complete with the relevant software required to transfer, store and evaluate test results to/ on a computer without the need for the operator to have advanced technical knowledge or other special skills.

The Process and Results

When testing impulse sealer seal strength, for instance, a section of the film/ foil used containing the seal is placed into the testing device, where it is then pulled apart at a constant, pre-defined rate (typically 10 – 12″/ minute) up to its breaking/ failure point. Throughout this process, resistance forces leading up to and at breaking point are measured.

The resulting data is transferred to relevant software on a computer, where it is then displayed in the shape of a graph representing the curve of resistance force vs. extension. Typically referred to as the tensile profile of the tested material/ seal, this graph reveals specific performance parameters of the given material up to breaking point. The chief points of interest for quality control/ designers are predominantly the material’s elastic limit and the force required to achieve breaking/ failure point.

The Aim of Tensile Testing

In the case of testing impulse sealer seal strength, the tensile tests are predominantly performed as peel tests. The goal of these tests is twofold, namely:

  1. To ensure the seal is strong enough not to break accidentally
  2. To ensure the seal will break when required without the use of excessive force/ strength

Take, for instance, medical packaging. Here, the impulse sealer seal strength must be high enough to ensure no accidental contamination of sterilized contents, medication, etc. through breakage of seals. At the same time, however, the end user must be able to open the package without having to apply enough force to the package to catapult the contents into the air – and subsequently all over the floor – when the seal finally breaks.

By examining and evaluating the results of tensile testing, designers/ quality control managers can determine the correct combination of film/ foil, sealing temperature and duration to provide the exact impulse sealer seal strength required to:

  1. Conform to relevant industry standards
  2. Offer comparative ease of opening to end users

The Importance of Tensile Testing

The question why tensile testing of seals is important is essentially answered by the two-fold aim of the process, namely compliance with relevant industry standards and ease of opening for end users. In essence, these tests ensure that the correct materials, temperatures and duration of sealing processes are combined to seal packages effectively and according to relevant standards.

In other words, they ensure packages cannot be opened accidentally or tampered with, resulting in contamination, premature decay, and corrosion and so on of the contents. At the same time, they assist in the determination of the maximum force required to open said packages. This, of course, is essential to ensure end users are able to open packages without the need for excessive force.