What Are The Different Types of Conveyors?
Screw (Auger) Conveyors
One of the first conveyors to be invented, screw conveyors have been around since ancient times (the Archimedes’ screw created in ancient Greece). The mechanism of this system consists of a helical blade (screw or auger) that moves liquid or granular materials, usually within a tube.
Auger conveyors are a good choice for semi-solid materials, such as:
- Animal feed
- Aggregates
- Food waste
- Wood chips
- Meat
- Boiler ash
- Municipal solid waste, and more
The rate of the material transfer is directly proportional to the rotation speed of the auger.
Downsides of this conveyor system include compromised blends or breakage of the material, reduced efficiency in high inclines, and the fact that it can’t be used in spaces where multiple planes are required. At the same time, if material integrity is not of essence (such as in transporting waste), augers have few moving parts and are easy to maintain and clean.
Aero-Mechanical Conveyors
The foundation of an aero-mechanical system is the generation of a centrifugal force. This type of conveyor includes a tube (usually made of steel) with an internally circulating rope. Discs are evenly spaced along this rope, and they move at very high speeds that create an airstream. When the material is fed into the air stream, it is fluidized and centrifugally ejected at the outlet.
Aero-mechanical conveyors are flexible, meaning they can operate both vertically and horizontally. They are easy to clean and convey materials at high capacity, depending on their application.
However, similarly to screw conveyors, these also compromise material integrity due to their high transport speeds. Additionally, rope-tensioning means they are relatively difficult to maintain. If the manufacturer wants to reduce the breakage of material, they have to find a slow and steady speed for their aero-mechanical conveyor.
Bucket Elevators
Bucket conveyor systems belong in the vertical conveyor category. They’re meant to move flowable bulk material loads (such as fertilizer or grain) upwards inside a series of buckets (multi-sided containers).
Aside from the buckets, an elevator also needs a belt to carry the buckets and transmit the pull, a power source to drive the belt, and accessories for collecting the material, loading the buckets, receiving the discharged material, enclosing the elevator if needed, and similar.
These conveyor systems have low driving power and are therefore quite efficient. However, bucket elevator components require high maintenance expenses, and the equipment is challenging to clean.
Pneumatic Conveyors
Pneumatic conveyor systems transfer dry bulk materials from one area to another through air pressure (positive pressure) or vacuum (negative pressure). The four basic elements of pneumatic conveyors are a source of air, a device for feeding material, a convey line and an air-material separator. These conveyors move material through a fully enclosed line which minimizes the possibility of material loss.
The best materials for air pressure or vacuum conveyors are fluidizable, fine, dry powders. Some pelletized or granular materials are also good options. Pneumatic conveying systems are a good fit for:
- Sugar
- Starch
- Wheat flour
- Food products
- Sands
- Metal powders
- Coal fines, and more
Belt Conveyors
Arguably the most common type of conveyors, belt conveyor systems, have found their rightful place in practically every industry. This system comes with pulleys (two or more) and a closed-loop (the conveyor belt) that rotates around them. One or more pulleys in the system can be powered, moving the belt in the right direction.
In general, there are two main types of belt conveyors:
- For general materials (boxes, packages, bags, solid items or products, etc.)
- For bulk materials (grain, salt, sand, ore, coal, etc.)
Belt systems are made of a wide variety of materials and are used in many different applications, not only in an industrial setting. You can see them at airports, transporting luggage, at restaurants, transporting food (especially sushi restaurants), at ski centers, transporting people and their ski equipment, and more. A belt conveyor can be enclosed to prevent contamination and loss of material, but also be open if it is part of assembly lines. They are a good choice for transporting heavier loads.
Chain Conveyors
As their name suggests, chain conveyors use an endless chain to transport material down a production line. The chain runs over sprockets at each end of the line, and it can have special attachments.
The most common application for chain conveyors is the movement of heavy loads – bulky materials that are very wide or very long (or both), such as industrial containers, grid boxes, and pallets. These systems can also be found in the pharmaceutical industry, as well as the automotive industry. Chain systems typically convey vehicle parts through paint plants, allowing for easier paint application.
These chains themselves are not difficult to maintain, as individual chain links can be replaced instead of replacing the entire chain. However, chains are not easy to clean, and their sprockets often need replacement, resulting in prolonged downtime and excessive maintenance.
Furthermore, chain conveyors require a lot of energy to operate, taking up quite a bit of power consumption. They are also not suitable for bulk materials because food and similar materials can accumulate in the chains and become a breeding ground for bacteria.
Cable Conveyors
Cable conveyor systems are perfect for preserving material integrity and minimizing direct contact with food materials, especially in tubular cable conveyors. These systems move material through a sealed tube with the help of a flexible, coated stainless steel drag cable. Solid discs are attached to the cable, pushing the material through the line.
Cable conveyors can move material in any direction you need – vertically, horizontally, at angles, and around corners. They have low energy costs because they run on motors of 7.5HP or less. These systems are also relatively easy to maintain because they have removable conveyor components.
The core feature of tubular cable conveyors is that they are incredibly gentle on the materials. They allow for consistent blending and minimizing product degradation, while at the same time maintaining a dust-free environment.
These conveyor systems are ideal for:
- Specialty grains
- Pet food
- Snack foods
- Breakfast cereal
- Coffee
- Nuts
- Frozen food
- Powdery materials
- Biomass
- Fluff plastic
- Specialty seeds
- Beans
- Industrial hemp, and more
Ideal Conveyor System
As evidenced by our brief outline of some of the most common conveyor types, there is no single perfect conveyor for every application. Instead, to select the one that works best for you, you must consider a wide range of aspects.
Take into account the size and height of the system compared to the floor space of your facility, as well as the type of material you want to be conveyed. Is it a delicate, powdered material? Loose material? What is its moisture content? Are you transporting heavy loads and large items?
Maintenance and cleaning costs, as well as possible downtime for each, should be considered. You don’t want your systems to be out of operation for too long when it’s time to maintain them.
If material integrity is crucial to you, make sure not to choose a system that may move at high speed but cause significant material damage. Look for conveyors that exhibit low material breakage.
If you want a system that is free of contaminants and that doesn’t taint the environment, you should go for an enclosed conveyor (like a tube conveyor). Most of the types we listed here come in an enclosed form as well.
Finally, compare the prices and quality of more than one conveyor vendor to ensure you are getting the highest value for your money.
Zarin Bespar Iranian – production of all kinds of conveyor belts, all kinds of sheets and rubber flooring, rubber lining, as well as all kinds of rubber parts and products with a capacity of 1500 tons per year
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