Woven Wire

Woven wire cloth is widely used for filtration and is available in a wide range of materials and mesh sizes. It can be woven from any material which is ductile enough to be drawn into a wire form. Preferred materials are phosphor bronze, stainless steel and monel (nickel alloy). Other materials widely used include aluminium alloys, copper plain mild steel or coated mild steel.

The minimum particle size of wire which can be used depends on the alloy, strength required, temperature and corrosion.
Mesh is described by form of weave and mesh count. A square mesh is the usual form in a plain or twilled weave.

For figuring out mesh sizes you have to count the number of openings from the center of any one wire to the center of a parallel wire one inch away. The number of openings is the mesh size. So a 2 mesh screen means there are two little squares across one linear inch of screen. A 100 mesh screen has 100 openings, and so on. Note, therefore that as the number describing the mesh size increases, the size of the particles decreases. Screens can be made with different thicknesses of wire. The thicker the wires, the smaller is the particle passing through that screen, and vice versa.

This formula can be used to calculate the space between the wires:

(in inch)

(in mm)

When working with these formulas you should be careful with the inch units. There is a difference between the English inch of 25.4 millimetres and the metric inch of 27.07 mm, whereby the latter is used very seldom.

Mesh is described more generally by aperture opening (space between the wires), eg

Coarse – aperture opening 1 to 12 mm
Medium – aperture opening 0.18 to 0.95 mm (180 to 950 mm)
Fine – aperture opening 0.020 to 0.160 mm (20 to 160 mm)

The best way to prevent misunderstandings is the description of the screen through the following characteristics:

- the metal sort or the alloy
- the space between the wires
- the thickness of wire

For example:

• A stainless steel gauze number 4 with a thickness of wire of 1.2 mm can be better characterised as
  
  stainless steel gauze;
  space between the wires 5.15 mm
  thickness of wire (diameter) 1.2 mm
• A monel gauze number 50 with a thickness of wire of 0.20 mm (200 micron) can be better characterised as
  
  monel gauze
  space between the wires 308 micron
  thickness of wire (diameter) 0.20 mm (200 micron)

A micron is another measurement we use for measuring mesh size. A micron is one-millionth of a meter or one twenty-five thousandth of an inch.

Aperture opening, open area

The aperture opening expresses the open area of the cloth. Wire Mesh contains open spaces (holes) and material. Open area is the total area of the holes divided by the total area of the cloth and is expressed as a percent. In other words, open area describes how much of the wire mesh is open space. This parameter can be calculated by means of the mesh number and the thickness of wire (D). With these two information is it possible to obtain the space between the wires and the open area for every existing mesh number.

(in inch)

(in mm)

(in %)

For an easier handling it is possible to use the following table, which provides the aperture opening and also the relation between space between wires and thickness of wire for every mesh number.

Example:

I.S.W.G.

In England the thickness of wire is not expressed through the wire diameter. Instead of that a number from the special I.S.W.G.-code is used. Other synonyms for this code are S.W.G. or B.W.G.
The table below gives an overview over all I.S.W.G. numbers including the thickness in inch and in millimetres.

Please also check our alternative filtration possibilities