The SATRA STM 638 abrasion test machine

How SATRA test equipment can be used to establish the abrasion resistance of materials

There are a number of test methods and associated test equipment for abrasion resistance testing of materials selected for footwear upper construction. The most common include the 'chisel scuff', 'Martindale', 'drum abrasion' and 'circular rub fastness' tests.  Another type of test, however, which can be used to evaluate the abrasion resistance of some types of footwear upper materials is the Taber test. This article describes SATRA’s three-station abrasion test machine and outlines how it is used as a 'Taber abrader'.

Each station of the STM 638 test machine comprises a circular horizontal table which is driven at a set rotational speed. The specimen to be evaluated in the test is attached via a central securing bolt to the table. Two independent and freely swinging arms, each fitted to a vertically mounted abrasive wheel, are positioned to allow the abrasive wheels to rest on the test specimen. The abrasive wheels are not driven, but are free to rotate. The contact points and orientation of the abrasive wheels with respect to the specimen (which are specified within the particular test method under consideration) are positioned in such a way that they rotate in the opposite direction to the table, due to the friction between the wheel and the test specimen.

How it works

The positioning of the abrasive wheels, with their axis of rotation offset from the axis of rotation of the specimen table centre, creates a lateral component to the movement of the specimen across the wheel, in addition to inducing the abrasive wheel rotation. This has the effect of making a more severe abrasion condition. The test method specifies the load which is applied between the abrasive wheel and the test specimen. This is achieved by applying weights to the swinging arms which carry the abrasive wheels. Different types of abrasive wheel can be used – for example, in EN ISO 5470 ('Rubber or plastic-coated fabrics – determination of abrasion resistance – part 1: Taber abrader'), both resilient and non-resilient wheel types are specified, along with the grit size of the abrasive.

"Taber abrasion tests would generally be judged as most appropriate for assessing the more severe cases of abrasion damage encountered for footwear uppers"

For each of the three stations of the STM 638, the number of revolutions required can be set. Each station will stop when the set number of cycles has been completed. While it would be typical to run three specimens at a time, they can also be controlled independently if required.

The assessment of the performance of test specimens is typically by visual observation of the abraded surface and weight loss from the test sample. In some cases, volume loss is reported which is normally calculated from weight loss and material density.

Taber tests have a particular role to play in abrasion testing. Typically, customers who use Taber abrasion testing build up their own experience of how the test results can be compared to actual product wear in use. In some cases, they have developed their own test methods. Test method SATRA TM163 – 'Abrasion resistance Taber method' lists both footwear lining materials and footwear upper materials as suitable for assessment. Taber abrasion tests would generally be judged as most appropriate for assessing the more severe cases of abrasion damage encountered for footwear uppers.

The STM 638 abrasion test machine is also suitable for assessing gloves against IEC 60903.

Publishing Data

This article was originally published on page 38 of the October 2012 issue of SATRA Bulletin.

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