What is abrasion testing for?
Today there are several ways to ensure the durability of materials and their suitability for specific applications. For example, abrasion tests help evaluate performance by measuring wear on the surface of a material. This wear results from repeatedly rubbing something against the test material; an example of this might be the rubbing of clothing that someone is wearing as they climb up and down a piece of furniture.
Friction is the dominant factor that causes your materials to deteriorate. The material is removed or displaced from a surface by hard particles from one surface being slid against another in abrasive wear. There are two primary forms of abrasion. Two-body wear abrasion and three-body wear abrasion.
Wear testing provides data for comparing materials or coatings and can help predict the life of your product. For example, two-body abrasion wear occurs when hard protrusions on one surface are slid against another. An example of this is the polishing of a sample using sandpaper. On the other hand, three-body abrasive wear occurs in systems where particles have the freedom to slide or rotate between two surfaces in contact; the case of contaminated lubricating oils in a sliding system can be a clear example of this type of abrasion. Wear rates in three-body abrasion are generally lower than in the two-body abrasion system.
Abrasion testing is used to test the abrasion resistance of solid materials. Materials such as metals, composites, ceramics, and thick coatings (weld and thermal spray coatings) can be tested with these methods. The purpose of abrasion testing is to generate data that reproduce materials in a repeatable manner in their resistance to scratch wear under certain conditions.
A custom wear test program can be set up to closely mimic actual operating conditions, such as temperature and fluids and the direction of wear.
The Wyzenbeek test is the standard in the United States and involves a machine in which the test material is squeezed over a frame and then rubbed back and forth. This motion is double rubbing and is counted until two breaks or wear in color is evident.
On the other hand, the Martindale test involves rubbing a piece of combed wool in a circular motion over a flat sample of the test material. Each pass is one cycle, and the number of revolutions the test material can withstand before showing a change is its abrasion rate. At the start of the test, checks are made every 1000 cycles to see if any wear is visible.
As can be seen, both Martindale and Wyzenbeek are fretting tests that measure different material properties. Martindale is an 8-shape rub test while Wyzenbeek performs rubbing along the warp and weft directions. Both tests are commonly used, for example, in the textile industry. Martindale is the most frequently performed test in Europe and is mainly used on wool and natural fibers. Wyzenbeek is the preferred test in the United States and is regularly used for testing synthetic fibers resistance.