DIN abrader

For many years, the only abrasion test method standardized internationally was the apparatus commonly known as the DIN abrader... 

ASTM has the DIN abrader specified as D596356. It has the rotating and non-rotating methods and both standard rubbers but does not cater for the lower force for soft rubbers. The details are said to be equivalent to the 1985 version of ISO 4649 and there is no indication of why it has not been updated. 

It is to some extent pointless to compare abrasion testers except in the context of their correlation with a particular product and service condition. If a general comparison is attempted, this will inevitably be subjective. However, it can be commented that the DIN abrader has become increasingly popular and is very convenient for routine control use. The... 

An elastomer with a low modulus will often have far better erosive wear than material with a higher modulus. An abrasive wear test (such as the DIN abrader) will show a poor result for a soft elastomer. This is also shown in field applications such as tire wear. When the application is changed from abrasive to erosive wear, the softer elastomer will wear very well. The reason for this is that the low modulus of the soft elastomer allows the stresses from each impact to be dissipated more readily than for hard polyurethanes. The soft material will stretch further and then snap back before damage is done. Any microcracks formed will have a slower growth rate and hence less erosion will occur. 

The DIN abrader is used extensively for wear testing. The test uses a metal drum (150-mm diameter) that is covered with a 60 mesh corundum abrasive cloth. The drum revolves at 40 revolutions per minute and the sample moves down the length of the drum. The 16-mm-diameter sample travels a distance of 40 m during the test. From the loss in weight of the sample and its density, the volume loss is calculated. Three runs are normally carried out to obtain an average result. 

The DIN abrader is quite widely used in Europe but finds little support in the USA. where the standard method is the PICO test described in ASTM D2228. In this method, abrasion is caused by two tungsten carbide knives, with a dusting powder applied to engulf abraded rubber particles. 

The DIN method is given in ISO 464954. The principle of the machine is illustrated in Figure 11.5 a disc test piece in a suitable holder is traversed across a rotating drum covered with a sheet of the abradant, which is why it is also called the rotary drum abrader. In this way, there is a relatively large area of abradant, each part of which is passed over in turn by the test piece, so that wear of the abradant is uniform and relatively slow. In the standard method there is no provision for changing conditions from those specified, other than a lower force for soft rubbers, but it would be possible to use other abradant cloths or papers and to vary the force on the test piece. The degree of slip is 100% and it would be inconvenient to test in the presence of a lubricant. Although not versatile, the method is very convenient and rapid and well suited to quality control. 

In addition, the rotary-platform, double-head abrader is specified for coated fabrics58 and the NBS abrader for shoe soles and heels59. The NBS abrader uses rotating drums with abrasive paper wrapped around them onto which the test pieces are pressed by means of levers and weights, but there is no provision for traversing the test piece across the abradant as in the DIN machine. 

Abrasion or resistance to abrasion is a function of the plastic, the ingredients in the plastic, the surface of the plastic, etc. Under test ASTM D1044 abrasion is related to loss in mg under standard conditions. Wear or abrasion has a relationship with the surface properties, i.e. coefficient of friction. DIN 53754E (Taber abrasion) is a similar test using a gritty material on an abrader wheel which measures wear against a number of wheel revolutions. 

A major use of MFs with alpha cellulose is in heavy-duty dishware. Decorative din-nerware with printed inlays (that is, designs located below the surface) cannot be washed off, abraded, or damaged in any manner. Surface glazing can be used to eliminate staining or scratching. Properly designed, they are practically unbreakable (see also Urea, below). 

Another surface property of paper is the abrasion resistance. The mechanical abrasion resistance of surfaces is determined in the friction wheel process (DIN 53 109-93). In this process, the amount of abrasion which is obtained by abrading the conditioned or wet sample with an abrasion wheel of defined quality under defined conditions is measured. 

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