The materials used to weave the cloth screens are quite varied. Screens are made from metal wires, plastic wires, and molded plastic cloths.
Alloys that are most weavable and resistant to corrosion are nickel/chrome steels; 304, 304L, 316, and 316L. These alloy wires are available in sizes down to 20 microns. The finest wire available is 304L, which is available to 16 microns. Other materials, including phosphor bronze, brass, copper, monel, nickel, aluminum alloys, plain steel, and plated steel, are also available. Within the drilling industry, 304 stainless cloth is the most common.
Two types of synthetic screens are available: woven synthetic polymer
and molded one-piece cloth, called a platform.
Conventional looms can be used to weave synthetic polymer screens. Polymers, such as polyesters, polypropylene, and nylon, are drawn into strings having diameters comparable to those of wire gauges and woven into screen cloth. Synthetic shaker screens exhibit substantial stretch when mounted and used on shale shakers. Because of this, plastic screen openings are not as precise, although this variability is not nearly as great as in layered metal steel screens.
One-piece injection molded synthetic cloths are typically made from urethane compounds. These synthetic cloths have limited chemical and heat resistance but display excellent abrasion resistance. The designs range from simply supported molded parts having very few open areas to complex structures with up to 55% open area. Molded cloths are
very popular in the mining industry, where abrasion resistance is important.
These screens make a coarser separation than screens used in the oilfield. Development of molded cloth screens capable of making a fine separation that have heat and chemical resistance necessary for oilfield application is under way.
Cloth selection for shale shaker screens involves compromises among separation, throughput, and screen life.