How to measure and analyse the texture of food, cosmetics, pharmaceuticals and adhesives.

Tuesday, 14 January 2014

Do you need to measure friction?

We're wondering whether you know that your Texture Analyser can be laid on its side, for cyclic friction assessment? 

In horizontal mode, the TA.XTplus texture analyser can be used to measure stiction, coefficient of friction, slip-stick and smoothness of material surfaces.

Friction is a phenomenon that is part of our daily lives - in one sense we would find most difficult to survive without it yet in another it can be most expensive to minimise. It can be simply identified as the resisting force that arises when one surface slides, or tries to slide, over another. It is commonly the textural or tactile property measured from packaging materials, lubricants, shaving gels, cosmetic sponges, etc.

Friction can be a limitation to us, for example, the friction of packaging can be a major limiting factor in the speed of packing machines. Additives such as polythene are often used to improve the lubricity or slip characteristics of surface.

There are two reactions due to friction that we can define and measure. There is 'static friction' (sometimes shortened to 'stiction'), that is the resistance to start relative movement and there is 'kinetic' or 'moving friction' – that is, the resistance to maintain the movement at a specific constant speed. Coefficient of friction is an empirical measurement – rougher surfaces tend to have higher values.

What’s the testing solution?

A Horizontal Friction System ensures that the instrument remains completely stable while in this orientation, and there is no negative effect on its mechanical operation. This system provides repeatable cyclic testing to measure friction in two directions during a test or continuous friction measurement for a number of cycles if required.  

The measurement does NOT include a wire and pulley system as this arrangement usually presents its own frictional components to the result and limits the test to single direction and non-cyclic friction measurements.
Flexible or rigid materials can be clamped onto the dedicated friction test bed and underside of the friction sled for the optional measurement of chosen material to material friction. 

A chosen weight can be added to the top of the friction to increase the contact between the two surfaces. The sliding friction is measured between the two surfaces sliding over each other for a chosen distance on the resulting curve which represents steady state behaviour.

This rig is one of a  wide range of attachments for testing packaging and other materials. 

Watch our video about testing of materials Putting Packaging to the Test Materials and Packaging Testing

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