Understanding how a Texture Analyser works – How to verify your test method

A range of validation samples

The test method and settings that have been selected as having the highest promise now needs to be tested in practice over the full range of texture variability of the product from excellent quality to very poor quality. A minimum of three levels of textural quality is often suggested. Whilst the repeatability within a sample is important, ultimately the method needs to be able to differentiate between a product which is clearly different. If it doesn't provide distinctly different results for products which you know to be different (if only by testing with your own hands) then it's back to the drawing board.

Understanding how a Texture Analyser works – Choosing the best test settings

When creating your optimum test method for texture/physical property measurement you will need to make choices on each of the setting values according to the type of test you have chosen.  The values will depend heavily on the sample.

Pre-test speed

The probe begins to move from its start point towards the sample at the pre-test speed.

When trying to find a trigger force your pre-test speed should really not exceed 3mm/sec for best initial data capture and the most accurate starting point.  A fast approach can lead to a late trigger (or ‘overshooting’) therefore entering the sample before data is being collected. Usually the pre-test speed is slower than the test speed.

Understanding how a Texture Analyser works – Choosing the best test method

The more that you know about various features of the Texture Analyser the better it will perform for you. The following takes you through the choices you will need to go through to determine what is the best test for your product and application.

Understanding how a Texture Analyser works – Adhesive testing

Adhesiveness (often referred to by consumers as ‘stickiness’ or ‘tackiness’) is key to perceived product quality, performance and effectiveness of such products as sealing tapes, curing glues, resins, waxes, adhesive plasters and labels used in the pharmaceutical, food, medical and packaging sectors. 

Testing adhesives is a very sophisticated process since it combines the Texture Analyser's ability to perform both compression and tension testing and measurement of force and distance. The sequence of events performed by the program are: 

Understanding how a Texture Analyser works – Hold control

The measurement of some properties requires the ability of the Texture Analyser to perform a hold period. This involves the application of either a specified force or specified probe position for a set period of time. Force hold periods are usually controlled by a PID (proportional, integral, differential) feedback loop, with PID settings adjustable by the user for the optimisation of the hold plateau, making it as smooth and uniform as possible. Below shows graphs recorded from two adhesive tests carried out with optimised and non-optimised PID control settings. After optimisation, the hold period is distinctly more uniform, giving a more reliable hold force.

Understanding how a Texture Analyser works – Cyclic testing

Cyclic mechanical tests are crucial for understanding the behaviour of materials under repeated loading and unloading conditions. These tests simulate real-world scenarios where materials are subjected to cyclic stresses, such as in automotive components, aerospace structures, and everyday consumer products.

Why are cyclic mechanical tests important?

1. Fatigue analysis: Cyclic tests help determine the fatigue life of materials, which is the number of cycles a material can withstand before failure. This is critical for components that experience repeated loading in their service life.
2. Durability assessment: These tests assess the long-term durability and reliability of materials under cyclic loading, providing insights into how materials will perform over time.
3. Material behaviour understanding: They help in understanding the viscoelastic, plastic, and elastic behaviours of materials under cyclic stresses, which is crucial for designing resilient and long-lasting products.
4. Product safety: Ensuring that materials can endure cyclic loading without significant degradation is essential for maintaining the safety and integrity of products.
5. Optimisation and development: Helps in optimising materials and designs for better performance and longevity by providing detailed data on material behaviour under cyclic conditions.

The importance of creep recovery tests and typical applications

Creep recovery tests are essential for understanding the viscoelastic properties of materials, specifically their ability to recover after being subjected to prolonged stress. These tests provide critical insights into the material's long-term performance, durability, and suitability for various applications.

What are creep recovery tests?

Creep recovery tests involve applying a constant stress to a material for a specific period (creep phase) and then removing the stress to observe how the material recovers (recovery phase). The test measures both the deformation under constant stress and the material's ability to return to its original shape once the stress is removed.

Understanding how a Texture Analyser works – Defining your test

Texture measurement is a critical aspect of quality control and product development in various industries, particularly in food, pharmaceuticals, and materials science. Texture analysis involves quantifying the physical properties of a material by applying forces and measuring the resulting deformation. Here's a step-by-step explanation of how tests are chosen, data is gathered and then curves are analysed for texture/physical property measurement.