Testing of Woven Wire Cloth according to ISO 9044
The wire diameter after weaving may be determined by using one of the following procedures:
- by measuring wires which have been loosened from the woven wire cloth (e.g. by using a micrometer screw),
- by measuring the wires in the cloth, if there is sufficient space for the measuring instrument.
The tolerance of the wire before weaving can no longer be determined in the woven wire cloth, because of its heavy deformation during weaving. The nominal wire diameter, however, can be calculated using the empirical weight formula.
In this simplified method, the number of pitches (p) in a given length (L) is determined. The given length is then divided by the number of pitches to give the average pitch. Subtraction of the wire diameter (d) from the average pitch then gives the aperture width (w).
To determine the arithmetical mean value of the aperture widths, as many pitches have to be measured as are nec- essary to obtain a representative value.
When measuring aperture widths between 16 and 1 mm 10 pitches have to be checked; smaller aperture widths – up to 0.1 mm – should be checked within 20 pitches.