This article takes an in-depth look at conveyor belts.
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A conveyor belt is a continuous looped belt driven by and wrapped around one or more pulleys. It is powered by an electric motor and supported by a metal plate bed or rollers on which the belt rests. The pulley that powers the conveyor belt is called the drive pulley, while the unpowered pulley is known as the idler pulley.
Pulley drives at the discharge end of a conveyor belt are referred to as head drives, whereas those at the infeed end are known as tail drives. The preferred type of pulley drive is a head drive located at the discharge end, which uses pull force to move the conveyor belt.
There are countless types and applications for conveyors, each designed to transport materials and goods along a continuously moving path. While motorized conveyor belts are the traditional form of conveying systems, some systems use rollers without motors to move materials.
Conveyor belts are utilized across various industrial settings and applications. They enhance productivity, reduce labor costs, and shorten lead times. Conveyor belts efficiently transport large quantities of goods quickly and reliably for further processing, assembly, or storage.
The main reasons for the widespread use of conveyor systems include labor cost savings, efficient goods movement, and protection of products and materials from damage. They offer optimal service at the lowest possible cost.
The surface of a roller bed conveyor belt is made up of a series of rollers selected based on production needs, such as speed, weight, and the types of products being transported. The length of the conveyor belt determines the number of rollers needed.
Roller bed conveyors are well-suited for applications requiring higher weight capacities. Their design reduces friction between the belt and the rollers, facilitating smooth movement of products.
A flat belt conveyor uses a series of pulleys to move materials and supplies. The belt, made from natural or synthetic materials, offers versatility and adaptability to various conditions and applications. In some cases, a flat belt conveyor may also include a center drive and nose bars.
A modular belt conveyor is constructed from interlocking hard plastic pieces, which facilitate easy segment removal and replacement. This design enhances cleaning efficiency and provides durability against sharp and abrasive substances. Modular belt conveyors are versatile and available in different configurations, capable of managing a single belt that navigates corners, straight sections, and both inclines and declines.
Cleated belt conveyors feature sections, pockets, or dividers that secure products during inclines or declines. The cleats can be spaced either evenly or unevenly and come in various styles and shapes, tailored to the product and the belt design.
Inverted Capital T – An inverted T cleat stands perpendicular to the belt and provides support for delicate and fragile materials.
Forward Leaning Capital L – A leaning capital L has a wide base that can be curved to scoop up granular materials. The design of the capital L makes it less resistant to leverage forces.
Inverted V – Inverted V cleats are two inches or less to create a trough-like effect and are used for heavy, abrasive, and large bulk materials.
Curved conveyor belts are designed to transport products around corners, facilitate transfers, and optimize floor space usage. They can make “U” turns to return in the opposite direction. Made with flat belts, these conveyors can turn at angles of 45°, 90°, 135°, and 180°.
Incline conveyor belts come in various types. Some feature a rough, uneven surface, while others include cleats to hold materials and prevent slipping or falling back. The underside of the belt typically has a smooth surface to ensure it glides smoothly along the bed. Modular conveyor belts can be utilized for this purpose, with cleats added as needed to enhance slippage prevention, depending on the material being transported.
The purpose of a decline conveyor belt is to move products or materials downward or adjust their height. Similar to incline conveyor belts, decline versions may feature a rough surface or cleats to prevent materials from slipping or falling.
Decline conveyor belts operate continuously with an articulated frame that includes a section pivoted or angled downward to facilitate the downward movement of products from an upper position.
Filter conveyor belts are designed to drain excess liquid from components or filter out toxins and contaminants. They feature lateral grooves and drainage holes in the center of the belt. These holes are located in a fabric-free zone or are sealed to prevent liquid from soaking into the belt material.
Similar to sidewall conveyor belts, filter conveyor belts can be equipped with sidewalls to prevent spills. They are typically made from heated polyester, polypropylene, polyolefin, or stainless steel mesh for dewatering applications.
Timing conveyor belts are designed for precise indexing and product placement. They ensure accurate positioning of products regardless of their size. Timing belt conveyors feature a timing pulley and an idler pulley, with a timing belt looped around them. The teeth on the timing belt align with the teeth on the pulleys, supported by a conveyor frame and support structures that hold the pulleys in place.
What sets timing belt conveyors apart from general conveyor belts is their precision in conveying and product placement. Timing belt conveyors can have various tooth spacings, with teeth that may be rounded or trapezoidal.
A sandwich conveyor belt consists of two face-to-face belts, with one positioned above the other to securely hold materials. The system includes a rotating wheel for adjusting the pressure and gap between the belts. Materials are sandwiched between the two belts, which grip them firmly. The upper belt is not motorized; instead, it is moved by the force of the lower, motorized belt.
Electrostatic charges on a conveyor belt can arise from friction between the belt and the bed, the movement of conveyed products, or ionization in the air. Although these static charges are usually low in intensity, they can cause problems if materials stick to the belt. Even minor charges can lead to sparks, creating potential hazards.
To manage and eliminate static charges, various devices can be installed on conveyor belt systems. For instance, anti-static belts may incorporate carbon particles or static-dissipative fabrics to reduce static buildup.
Conveyor belts consist of a loop or band of rollers connected to rotors, which are driven by a motor. These belts can vary in width from as narrow as one inch (25 mm) to as wide as five feet (1.5 m), with plastic modular belts reaching up to ten feet (3 m). They are constructed from highly durable and robust materials, similar to those used in heavy-duty machinery.
The design of the belt offers both structure and traction, facilitating the efficient movement of goods and materials.
The motor on a conveyor belt drives the pulleys, which in turn move the belt. Adequate friction between the belt and the pulleys ensures that the belt stays in place. The motor's force rotates the drive pulley, causing the conveyor belt to move.
Pulleys are placed at both ends of the conveyor belt and near the drive motor. The drive pulley, which is powered by the motor and reducer, propels the conveyor belt and features external bearings. To minimize belt slippage, pulleys are equipped with crowned lagging.
Return, idler, or tail pulleys guide the conveyor belt back to the drive pulley. These pulleys, which have internal bearings, are located at the end of the conveyor bed or at both ends in a conveyor with a central drive. Tail pulleys are crucial for maintaining tension in the conveyor belt.
The conveyor belt is held up by a dead plate within its frame. To support the belt during its return to the infeed, rollers are positioned both underneath and outside the conveyor. Each roller is equipped with a spring-retained axle in its center shaft, facilitating straightforward installation and removal.
Conveyor belts come in a vast array of types, sizes, shapes, angles, and materials. The design and type of conveyor belt in a system dictate its functionality, as they are specifically engineered to transport materials and products from one place to another.
No matter the material used to manufacture a conveyor belt, their primary purpose is to transport products, materials, supplies, and components efficiently and smoothly from one location to another. The nature of the product being conveyed largely dictates the type of conveyor belt required, guiding the selection process.
While conveyor belts can be made from a wide range of materials, they generally fall into five main categories: metal, plastic, rubber, fabric, and leather. Each of these categories contains various subgroups and specific variations.
Plastic conveyor belts are lightweight and temperature-resistant, constructed from thermoplastics like polyurethane, polyester, polyvinyl chloride, silicone, and polyethylene. Their interlocking segments allow for bending, curving, and movement on inclines or declines, providing flexibility in any direction. These interlocked plastic conveyor belts serve as an alternative to metal and fabric options.
Woven metal or plate conveyor belts are known for their strength, durability, rigidity, and flatness. Solid metal conveyor belts retain their shape throughout their lifespan, whereas woven and linked belts may stretch and deform over time. Metal conveyor belts are designed to operate in straight lines, without curves, turns, or deviations in their path. Constructed from stainless steel, aluminum, or carbon steel, they offer exceptional longevity.
Rubber has long been a popular material for conveyor belts, known for its durability and abrasion resistance. Common rubber types used in conveyor belts include neoprene, nitrile, and styrene butadiene, all of which are reinforced with cloth fabric.
Rubber’s durability makes it suitable for harsh environments where abrasion resistance and impact absorption are essential. The cloth reinforcement helps prevent the rubber from stretching and deforming.
Fabric conveyor belts offer a cost-effective solution for short conveyor systems with lower capacity requirements. These belts are constructed from multiple layers of synthetic fabrics, treated to resist elongation, and feature lengthwise polyester threads combined with crosswise polyamide threads. This combination results in an exceptional tensile strength-to-weight ratio, along with flexibility, impact resistance, and chemical resistance.
The top covers of fabric conveyor belts are made from materials such as polyurethane (PU), polyvinyl chloride (PVC), and silicone. Additionally, rubber cover grades can be applied to enhance resistance to fire, heat, and wear.
Types of fabric conveyor belts include:
Leather conveyor belts, among the earliest types of conveyor belts, continue to be used today due to their durability, shock resistance, and excellent gripping capabilities. In contemporary applications, leather is often employed in custom and hybrid conveyor systems. Like other conveyor belts, leather belts come in a range of widths and thicknesses and can be reinforced or coated with different materials to improve their performance. Leather conveyor belts are versatile and can handle all traditional conveyor tasks, including the movement of products on inclines and declines.
Conveyor belts are integral to any industry that needs to transport materials or supplies within a facility. These systems have become crucial to industrial operations of all sizes due to their ability to move products quickly and efficiently, significantly enhancing supply chain performance. In larger, more complex facilities, automated conveyor systems are employed to maximize efficiency, save time, and boost productivity.
Conveyor belts serve a wide range of applications, from small systems used to transport jewelry and precious stones to large outdoor conveyors designed for moving rocks, coal, and ore. Their versatility makes conveyor belt systems a popular choice for the rapid and cost-effective movement of various materials.
The various uses of conveyor belts can be broken into general and bulk material handling, food processing, and manufacturing and assembly operations.
Bulk conveyor belts are designed to transport a diverse range of products and raw materials, such as sugar, oats, cereal, fruit, flour, screws, nut fasteners, and food nuts. They efficiently handle the loading and unloading of bulk materials like cement, sand, and gravel. In the mining industry, bulk conveyor belts are used to move coal, minerals, rocks, and stones from both open and closed pit operations. The adjustable lengths of these conveyor belts facilitate the removal of minerals and waste materials.
Mobility plays a crucial role in the loading and unloading of ships. During loading, a belt conveying system transfers materials from trucks into the ship's hold. For unloading, the process is reversed, with materials moved from the ship to trucks. To accommodate the varying heights of different ships, loading and unloading belt conveyors are designed to telescope, allowing for height adjustments.
Assembly operations utilize a series of conveyors custom-designed to meet specific needs. As robotics and automation become increasingly prevalent in assembly lines, belt conveying systems are evolving rapidly to keep pace with computerized innovations and operational demands.
For automated assembly lines, various belt conveyor types are employed, including chain, slider, hinged, plastic belt, and pallet conveyors. The growing need for fast and efficient material movement has driven the development of new and innovative belt conveyor configurations.
Belt conveyors are essential for efficient airport operations, ensuring the quick movement of packages, cargo, and luggage. Successful integration of a belt conveying system into airport material handling requires compatibility with other handling and checking systems.
Specifications for airport belt conveyor systems include reliability, quiet operation, attractive design, safety, and ease of maintenance. Each airport conveyor system is customized to fit the airport’s layout, accommodating specific angles, flow rates, and one- or two-way operation.
Parts belt conveyors are capable of transporting various types of parts, regardless of size or design, including hot, oily, and pressed components from forging machines that need to be moved into hoppers, storage units, and drums. Piano hinges are commonly used in these systems due to their durability, strength, and rigidity. Given the weight and density of the parts being handled, the belts are constructed from shock- and impact-resistant materials and feature sidewalls to prevent spillage.
Excavation belt conveyors are specifically designed to move earth and materials through confined spaces such as windows, doors, and vents. These conveyors are equipped with belt buckets that can handle loads of varying weights and offer high load capacity. Despite their ability to manage heavy loads, excavation belt conveyors are designed to be maneuvered and positioned easily by two or three workers.
Standards and regulations for belt conveyors are established by various agencies, depending on the specific industry. These include the Mine Safety and Health Administration (MSHA), the Food and Drug Administration (FDA), the Conveyor Equipment Manufacturers Association (CEMA), and the Occupational Safety and Health Administration (OSHA). Additionally, rubber industry associations such as the US Rubber Manufacturers Association (RMA) and the Association for Rubber Products Manufacturers (ARPM) provide guidelines for the manufacturing, certification, and production of rubber conveyor belts.
FDA regulations for conveyor belts fall under the Food Contact Material (FCM) guidelines, which govern any equipment that comes into contact with food. These regulations are detailed in Title 21, Chapter 1, Sub-chapter B of the Code of Federal Regulations.
MSHA regulations are specified in sections 56, 57, 75, and 77, covering surface and underground mining, coal mining, and non-metallic mining. MSHA operates under the United States Department of Labor.
OSHA's primary focus is on worker health and safety. Conveyor safety standards are outlined in section 1926.555, which includes requirements for safety stops, emergency stops, conveyor passes, and other protective measures.
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