The structure of conveyor belts
The belt consists of one or more layers of material. It is common for belts to have three layers: a top cover, a carcass and a bottom cover. The purpose of the carcass is to provide linear strength and shape. The carcass is often a woven or metal fabric having a warp & weft. The warp refers to longitudinal cords whose characteristics of resistance and elasticity define the running properties of the belt. The weft represents the whole set of transversal cables allowing to the belt specific resistance against cuts, tears and impacts and at the same time high flexibility. The most common carcass materials are steel, polyester, nylon, cotton and aramid. The covers are usually various rubber or plastic compounds specified by use of the belt.
Steel conveyor belts are used when high strength class is required. For example, the highest strength class conveyor belt installed is made of steel cords. This conveyor belt has a strength class of 10.000 N/mm and it operates at Chuquicamata mine, in Chile.Polyester, nylon and cotton are popular with low strength classes. Aramid is used in the range 630 - 3500 N/mm. The advantages of using aramid are energy savings, enhanced lifetimes and improved productivity. As an example, a 2250 N/mm, 3400 m long underground belt installed at Baodian Coal Mine, part of in Yanzhou Coal Mining Company, China, was reported to provide energy savings of >15%.
This article is reprinted from wikipedia