About Premetz

Premetz is a new way to analyse Prefil curves, to give a more reliable and accurate assessment of the level of inclusions in molten aluminium.

The Prefil test passes typically 1.4kg of liquid aluminium under pressure through a filter, recording the weight filtered as a function of time.

For perfectly clean metal (no inclusions present), the weight filtered should increase linearly with time, depending only on the permeability of the filter.

The plot shows the sorts of weight versus time plots you would expect for different filter permeabilities (measured in darcy units). The range of permeabilities shown covers those typically exhibited by commercially available Prefil filters (note the permeability of a filter to liquid aluminium is generally very different from the quoted permeability as measured by passing compressed air through the filter).

One of the biggest weaknesses of the traditional Prefil test is the variation in filter permeability from test to test, which can easily swamp any variation in metal quality between tests.

The Premetz method has been developed to eliminate this limitation, and to provide a better, more reliable quantification of metal cleanliness.