A conveyor belt is the carrying medium of a belt conveyor system (often shortened to belt conveyor). A belt conveyor system is one of many types of conveyor systems. A belt conveyor system consists of two or more Conveyor pulley (sometimes referred to as drums), with an endless loop of carrying medium—the conveyor belt—that rotates about them. One or both of the pulleys are powered, moving the belt and the material on the belt forward. The powered Conveyor pulley is called the drive pulley while the unpowered pulley is called the idler pulley. There are two main industrial classes of belt conveyors; Those in general material handling such as those moving boxes along inside a factory and bulk material handling such as those used to transport large volumes of resources and agricultural materials, such as grain, salt, coal, ore, sand, overburden and more.
Rubber conveyor belts are commonly used to convey items with irregular bottom surfaces, small items that would fall in between rollers (e.g. a sushi conveyor bar), or bags of product that would sag between rollers. Belt conveyors are generally fairly similar in construction consisting of a metal frame with rollers at either end of a flat metal bed. The belt is looped around each of the rollers and when one of the rollers is powered (by an electric motor) the belting slides across the solid metal frame bed, moving the product. In heavy use applications the beds which the belting is pulled over are replaced with rollers. The rollers allow weight to be conveyed as they reduce the amount of friction generated from the heavier loading on the belting.
Belt conveyors can now be manufactured with curved sections which use tapered rollers and curved belting to convey products around a corner. These conveyor systems are commonly used in postal sorting offices and airport baggage handling systems. A sandwich belt conveyor uses two conveyor belts, face-to-face, to firmly contain the item being carried, making steep incline and even vertical-lift runs achievable.
Belt conveyors are the most commonly used powered conveyors because they are the most versatile and the least expensive. Product is conveyed directly on the belt so both regular and irregular shaped objects, large or small, light and heavy, can be transported successfully. These conveyors should use only the highest quality premium belting products, which reduces belt stretch and results in less maintenance for tension adjustments. Belt conveyors can be used to transport product in a straight line or through changes in elevation or direction. In certain applications they can also be used for static accumulation or cartons.
In 1957, the B. F. Goodrich Company patented a Möbius strip conveyor belt, that it went on to produce as the "Turnover Conveyor Belt System". Incorporating a half-twist, it had the advantage over conventional belts of a longer life because it could expose all of its surface area to wear and tear. Such Möbius strip belts are no longer manufactured because untwisted modern belts can be made more durable by constructing them from several layers of different materials. In 1970, Intralox, a Louisiana-based company, registered the first patent for all plastic, modular belting.
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.. "Awarding of the World's Most Powerful Belt Conveyor System" Mining.com, 15-04-2016. Retrieved on 2017-10-11 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.Lodewijks G. (2011), "The Next Generation Low Loss Conveyor Belts", Proceedings of the Beltcon 16 conference, Johannesburg, Republic of South Africa, August 3–4, 2011.. Engineering and Mining Journal 5-12-2014. Retrieved on 2017-10-11 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%.Ven H.J.F.M., Beers H., Jinglei W, Martins C., Mendez E. (2017), "Aramid in conveyor belts in operation: extended lifetime, energy savings and environmental effects", Proceedings of the Beltcon 19 conference, Pretoria, Republic of South Africa, August 2–3, 2017"
Some of the major global conveyor belt manufacturers and service providers are Berndorf AG, Continental AG, Fenner plc, Kale Conveyor, Terra Nova Technologies, ThyssenKrupp, HESE Maschinenfabrik GmbH and Tenova Takraf.
The longest conveyor system in an airport is the Dubai International Airport baggage handling system at . It was installed by Siemens and commissioned in 2008, and has a combination of traditional belt conveyors and tray conveyors.
Boddington Bauxite Mine in Western Australia is officially recognised as having the world's longest and second-longest single belts with a belt feeding a 20 km (12.5 miles) long belt. This system feeds bauxite through the difficult terrain of the Darling Ranges to the Worsley Alumina refinery. The longest single-belt international conveyor runs from Meghalaya in India to a cement factory at Chhatak Bangladesh.Alspaugh, Mark, Bulk Material Handling By Conveyor Belt 7, p 83 It is about 17 km long and conveys limestone and shale at 960 tons/hour, from the quarry in India to the cement factory (7 km long in India and 10 km long in Bangladesh). The conveyor was engineered by AUMUND France and Larsen & Toubro. The conveyor is actuated by three synchronized drive units for a total power of about 1.8 MW supplied by ABB (two drives at the head end in Bangladesh and one drive at the tail end in India). The conveyor belt was manufactured in 300-meter lengths on the Indian side and 500-meter lengths on the Bangladesh side, and was installed on-site by BeltPro (formerly NILOS India). The idlers, or rollers, of the system are unique in that they are designed to accommodate both horizontal and vertical curves along the terrain. Dedicated vehicles were designed for the maintenance of the conveyor, which is always at a minimum height of above the ground to avoid being flooded during monsoon periods.