Mesh consists of wires or fibers woven or knitted into a grid or screen pattern to create a semi-permeable barrier. Types of mesh include screen and netting. When referred to as its own product in comparison to screen, mesh is generally finer and opening measurements are determined by the mesh size or linear density of wires (wire per inch) rather than opening size.
Mesh is used in a variety of processes that require straining or sorting. Applications for mesh include filtration, material handling products, radio frequency radiation shields (e.g. microwave ovens), screen printing, and surgical procedures.
Mesh size, linear wire density, and opening area are the most important physical characteristics of mesh selection.
Mesh size (or mesh count) refers to the number of openings per linear inch, measured from the center of any wire. Larger openings are listed as fractions (5/8" to 1"), which is the distance between the centers of two adjacent wires.
Linear wire density is the density of wire per length of mesh. It incorporates the wire or strand diameter and the opening size. These affect the durability and cost of the mesh, as they determine the amount of material used in its construction.
Opening area is the dimension between adjacent parallel wires. It is usually expressed as a percentage of open area of total coverage of cloth.
Note that for each mesh, products will vary by both wire diameter (wire density) and mesh size. For example, a medium mesh with a wire diameter of 0.015" may come as either 18 x 18 or 22 x 22 mesh.
Materials of Construction
It may be important to select mesh based on the materials used in its construction, depending on the demands and specifics of the application. Material selection determines a mesh's strength, chemical and corrosion resistance, hardness, and electrical conductivity. Materials can be classified as metals, plastics, natural fibers, or other unique materials.
Metals and metal alloys are the most common material used to make mesh products. They tend to be strong and durable materials, and have the ability to be deformed under stress without breaking or cleaving. The most common metals used for mesh are steel, stainless steel, nickel, aluminum, brass, and copper.
Plastics and polymers include a wide range of synthetic and semi-synthetic solids. Two classifications of plastics are thermoplastics and thermosetting polymers. Thermoplastics do not undergo chemical change when heated and can be molded again. Thermosets stay solid after taking shape initially. Depending on the type of polymer, plastics offer a range of advantages such as low cost, corrosion resistance, low friction, and flexibility. Polymers include polyethylene, polypropylene, PVC, PTFE, and nylon.
Natural fibers are softer, naturally occurring fibrous materials. They include cotton, hemp, and silk. Strands from these materials are woven to create more durable wires and ropes. Natural fibers are made into various types of decorative screen meshes and some types of netting, but tend to not have the strength or resilience that stronger materials offer.
Fiberglass is a unique material consisting of numerous extremely fine fibers of glass. It is lightweight, extremely strong, and robust material. Its bulk strength and weight properties are also very favorable when compared to most metals, but it can also be more expensive. Fiberglass mesh tends to be more opaque than standard mesh materials, allowing for greater visibility and light allowance.
The type of weave used to design a mesh product can also be an important part of the selection process.
Plain woven construction is is the most popularweave.Each weft wire passes alternately over and under each warp wire and each warp wire passes alternately over and under each weft wire. Warp and weft wire diameters are generally the same.
Plain dutch constructionhas similar interlacing as in plain weave, except the warp wires are larger in diameter than the shute wires. The lighter shute wires are driven up close thus forming a dense filtering medium. This weave displays a tapered or wedge-shaped opening. While the warp wires remain straight, the weft wires are plain woven to lie as close as possible against each other in a linen weave forming a dense, strong material with small, irregular and twisting passageways that appear triangular when diagonally viewing the weave.
Twill construction proceeds so each warp wire and each shute wire pass successively over and under the two adjacent wires -- in both the warp and shute directions. This over and under movement is shifted one wire with each pass of the shuttle. This pattern permits the weaving of heavier wires in varying meshes. Twill weave is normally used to allow a heavier than standard wire diameter in association with a given mesh.
Dutch twill constructiontechnically combines the twill weave and Dutch weave. The larger diameter warp wires successively pass over and under the lighter diameter shute wires. Each pass of the shute wires shifts the over and under movement. The shute wires are driven up close, resulting in a tightly woven filter cloth with tapered or wedge shaped openings.