What is an adhesion test?
Adhesion is the force that resists the separation of two bodies in contact. An adhesion test measures the adhesive characteristics of a product by measuring the forces to separate the product from the test surface which it comes into contact with. Adhesiveness ('Stickiness') is most commonly measured with a cylinder probe, which is pressed (application of compression), onto the surface of the sample after which the force to pull the probe off it is measured. The higher the force to separate these surfaces, the more adhesive is the product. The distance the probe needs to be pulled away from the product before the two surfaces are separated will also indicate its viscoelastic behaviour, and depending upon the product, its ‘tailing’ or ‘stringiness’ characteristic.
The success of the measurement depends on the means of being able to hold the sample in order to pull away from it and measure the ‘withdrawal’. Stable Micro Systems has a wide range of solutions for the purpose of holding down a product in order to be able to successfully measure its adhesive properties. The operator is given the ability to control the data acquisition rate (2000pps advised for maximum detail collection from a quick test), the probe separation rate, the probe material and a controlled force to apply to the sample.
Why perform an adhesion test?
Adhesive properties can be the most desirable characteristic of a product e.g. adhesive pastes or tapes, confectionery products and thereby their salient feature or can be a major issue for a product, e.g. dough, and can cause production stoppages and product failures. The ability to measure this property will allow manufacturers to control the quality of a product or assess stages in production so as to avoid downtime
In Exponent software a special test is available called an ‘Adhesive Test’ which focuses on the measurement of this property. It allows the testing probe to approach the sample at a chosen speed and then apply a chosen force for a chosen period of time (to allow a good controlled bond to be achieved between the two surfaces). After this time the probe then withdraws to a chosen distance at a chosen speed in order to measure the force to separate the two surfaces and provide a measure of stickness/adhesiveness. The maximum force is usually taken as the measurement of stickiness. Area under the positive region of the curve is termed 'Work of Adhesion' and the distance travelled away from the sample before separation is often used as a measure of 'cohesiveness'. In the case of e.g. mozzarella cheese and caramels this distance has been termed 'stringiness' or ‘tailing’, and for adhesives and paints has been termed as 'peaking' or 'legging'.
Properties that can be measured with an adhesion test
Adhesion tests are typically chosen to measure:
Adhesiveness, stickiness, tackiness, peel force, cohesiveness, tailing, stringiness, legging, work of adhesion etc.
To understand how these properties are measured visit the Textural Properties page.
Typical probes and fixtures used for adhesion tests
To understand how these fixtures are designed and manufactured visit the Texture Analysis Attachments page.
Items with codes prefixed 'HDP/' must be used with the HDP/90 Heavy Duty Platform.
Items tagged * are Community Registered Designs.
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Adhesion Testing is an area which may present you with some challenges in terms of effective use of your time and repeatability of your results. Our articles aim to help you explain some of the core principles to enhance your testing experience and overcome some of the difficulties you will encounter in this field of testing and explain the effective use of the test device options.
Read our blog post about Investigating the Full Picture of Adhesive Testing.