Intro to Knitted Wire Mesh
Knitted wire mesh consists of a metal wire strand knitted into a mesh structure in very much the same way as stockings or sweaters. Knitting produces mesh of interlocking loops and these loops move relative to each other in the same plane without distorting the mesh, giving knitted mesh a two-way stretch not found in woven wire products.
Forms of Knitted Mesh
Knitted mesh is produced on a cylindrical machine and produced as a continuous tube of mesh which is pulled through the knitter by take-up rollers which also flatten the tube into a two-ply mesh in widths between approximately1” and 42” wide. It can be used directly in this flattened form for many applications or it can be further processed into several other basic forms.
Flattened mesh is oftentimes run through corrugating rollers to create crimped mesh. In this form, the corrugations act like springs for resiliency and give the mesh added thickness and increased height.
Crimped mesh is also used to create compressed, die-formed units for use as filters, shock isolators, flame arrestors and other durable items. In this case, the mesh is formed in a custom made die-set. These parts are available in densities (% metal by volume) ranging from 10% to 60%. Compressed mesh can also be made in a continuous strip form by running the mesh through calendaring rollers.
Mesh can also be knitted into a hollow tube which is then pulled through dies and over forming balls to make rope-seals, spring-tubes and core material for tadpole and other high-temperature gaskets.
Properties of Knitted Mesh
Knitted mesh has distinct advantages over most competitive materials. Because each loop acts as a small spring when subjected to tensile or compressive stress, knitted metal has an inherent resiliency. If it’s not distorted beyond its yield point, the material will resume its original shape when the stress is removed. Even when it’s compressed into a special shape, a high degree of resiliency is retained. Varying the knitted structure, wire diameter, strand count, wire material and forming pressure used to create the part can help control this characteristic.
Among the most important property of knitted mesh units is the material itself. By careful selection of the material or combinations of materials, Metal Textiles can custom engineer solutions best suited for our customer’s application—be it corrosive, ultra-high or cryogenic temperature, high pressure, radioactive, dirty, oily or other extreme conditions.
Most Commonly Knit Materials
- Stainless Steel (300 and 400 series)
- Plain Steel
- Galvanized Steel
- Tinned Copper
- Gold Alloy
- Gold Plated Copper
- Silver Plated Copper
- Silver Plated Brass
- Gold Alloy
“Inconel”, “Monel”, “Nylon”, “Hastelloy”, and “Teflon” are registered product names of their respective trademark holders
Mesh is normally knit from wires ranging in diameter from .0035” to .0200”. These wires can be round or flat such as those used in Metal Textiles copper gauze for cleaning and in air-filtration applications where large surface areas of wire are needed (a round wire when flattened has approximately twice as much surface area).
In filtration applications, wire diameter is perhaps the most important design variable. It directly affects flow, dirt holding capacity, efficiency and pressure drop. In general, larger diameter wire allows for higher flow but provides lower dirt holding capacity.
Density refers to the either the number of wire strands per mesh loop (ranging from single strand to 12 individual strands) or the mass of material per unit volume of a die-formed part. As such, finished part density relates to the density of the original mesh and the amount of material and forming pressure used to compress the mesh into its final form to achieve the desired performance.