My Techno Laboratories : Types of Conveyors

Conveyors

A conveyor system is a common piece of mechanical handling equipment that moves materials from one location to another. Conveyors are especially useful in applications involving the transportation of heavy or bulky materials. Conveyor systems allow quick and efficient transportation for a wide variety of materials, which make them very popular in the material handling and packaging industries. Many kinds of conveying systems are available, and are used according to the various needs of different industries. There are chain conveyors (floor and overhead) as well. Chain conveyors consist of enclosed tracks, I-Beam, towline, power & free, and hand pushed trolleys.

Types of Conveyors

Conveyors are used to move materials over a fixed path. The major types of conveyors are:

Conveyors are used:

When material is to be moved frequently between specific points
To move materials over a fixed path
When there is a sufficient flow volume to justify the fixed conveyor investment

Conveyors can be classified in different ways:

Type of product being handled: unit load or bulk load
Location of the conveyor: overhead, on-floor, or in-floor
Whether or not loads can accumulate on the conveyor

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1. Chute Conveyor

Unit/Bulk + On-Floor + Accumulate

Inexpensive

Used to link two handling devices

Used to provide accumulation in shipping areas

Used to convey items between floors

Difficult to control position of the items

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2. Wheel Conveyor

Unit + On-Floor + Accumulate

Uses a series of skatewheels mounted on a shaft (or axle), where spacing of the wheels is dependent on the load being transported

Slope for gravity movement depends on load weight

More economical than the roller conveyor

For light-duty applications

Flexible, expandable versions available

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3. Roller Conveyor

Unit + On-Floor + Accumulate

May be powered (or live) or nonpowered (or gravity)

Materials must have a rigid riding surface

Minimum of three rollers must support smallest loads at all times

Tapered rollers on curves used to maintain load orientation

3(a) Gravity Roller Conveyor

Alternative to wheel conveyor

For heavy-duty applications

Slope for gravity movement depends on load weight

For accumulating loads

3(b) Live (Powered) Roller Conveyor

Belt or chain driven

Force-sensitive transmission can be used to disengage rollers for accumulation

For accumulating loads and merging/sorting operations

Provides limited incline movement capabilities

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4. Chain Conveyor

Unit + In-/On-Floor + No Accumulate

Uses one or more endless chains on which loads are carried directly

Parallel chain configuration used to transport pallets

Vertical chain conveyor used for continuous high-frequency vertical transfers (cf. vertical conveyor used for low-frequency intermittent transfers)

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5. Slat Conveyor

Unit + In-/On-Floor + No Accumulate

Uses discretely spaced slats connected to a chain

Unit being transported retains its position (like a belt conveyor)

Orientation and placement of the load is controlled

Used for heavy loads or loads that might damage a belt

Bottling and canning plants use flat chain or slat conveyors because of wet conditions, temperature, and cleanliness requirements

Tilt slat conveyor used for sortation

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6. Flat Belt Conveyor

Unit + On-Floor + No Accumulate

For transporting light- and medium-weight loads between operations, departments, levels, and buildings

When an incline or decline is required

Provides considerable control over the orientation and placement of the load.

No smooth accumulation, merging, and sorting on the belt

The belt is roller or slider bed supported; the slider bed is used for small and irregularly shaped items

In 1957, B.F. Goodrich, Co. patented the Möbius strip for conveying hot or abrasive substances in order to have "both" sides wear equally [14]

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7. Magnetic Belt Conveyor

Bulk + On-Floor

A steel belt and either a magnetic slider bed or a magnetic pulley is used

To transport ferrous materials vertically, upside down, and around corners

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8. Troughed Belt Conveyor

Bulk + On-Floor

Used to transport bulk materials

When loaded, the belt conforms to the shape of the troughed rollers and idlers

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9. Bucket Conveyor

Bulk + On-Floor

Used to move bulk materials in a vertical or inclined path

Buckets are attached to a cable, chain, or belt

Buckets are automatically unloaded at the end of the conveyor run

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10. Vibrating Conveyor

Bulk + On-Floor

Consists of a trough, bed, or tube

Vibrates at a relatively high frequency and small amplitude in order to convey individual units of products or bulk material

Can be used to convey almost all granular, free-flowing materials

An Oscillating Conveyor is similar in construction, but vibrates at a lower frequency and larger amplitude (not as gentle) in order to convey larger objects such as hot castings

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11. Screw Conveyor

Bulk + On-Floor

Consists of a tube or U-shaped stationary trough through which a shaft-mounted helix revolves to push loose material forward in a horizontal or inclined direction

One of the most widely used conveyors in the processing industry

Many applications in agricultural and chemical processing

Water screw developed circa 250 BC by Archimedes

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12. Pneumatic Conveyor

Bulk/Unit + Overhead

Can be used for both bulk and unit movement of materials

Air pressure is used to convey materials through a system of vertical and horizontal tubes

Major advantages are that material is completely enclosed and it is easy to implement turns and vertical moves

12(a) Dilute-Phase Pneumatic Conveyor

Moves a mixture of air and solid

Push (positive pressure) systems push material from one entry point to several discharge points

Pull (negative pressure or vacuum) systems move material from several entry points to one discharge point

Push-pull systems are combinations with multiple entry and discharge points

12(b) Carrier-System Pneumatic Conveyor

Carriers are used to transport items or paperwork (e.g., money from drive-in stalls at banks)

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13. Vertical Conveyor

Unit + On-Floor + No Accumulate

Used for low-frequency intermittent vertical transfers (cf. vertical chain conveyor can be used for continuous high-frequency vertical transfers

13(a) Vertical Lift Conveyor

Carrier used to raise or lower a load to different levels of a facility (e.g., different floors and/or mezzanines)

Differs from a freight elevator in that it is not designed or certified to carry people

Can be manually or automatically loaded and/or controlled and can interface with horizontal conveyors

13(b) Reciprocating Vertical Conveyor

Utilizes gravity-actuated carrier to lowering loads, where the load overcomes the magnitude of a counterweight

Can only be used to lower a load

Alternative to a chute conveyor for vertical "drops" when load is fragile and/or space is limited

Can be manually or automatically loaded and/or controlled and can interface with horizontal conveyors

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14. Cart-On-Track Conveyor

Unit + In-Floor + Accumulate

Used to transport carts along a track

Carts are transported by a rotating tube

Connected to each cart is a drive wheel that rests on the tube and that is used to vary the speed of the cart (by varying the angle of contact between the drive wheel and the tube)

Carts are independently controlled

Accumulation can be achieved by maintaining the drive wheel parallel to the tube

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15. Tow Conveyor

Unit + In-Floor + Accumulate

Uses towline to provide power to wheeled carriers such as trucks, dollies, or carts that move along the floor

Used for fixed-path travel of carriers (each of which has variable path capabilities when disengaged from the towline)

Towline can be located either overhead, flush with the floor, or in the floor

Selector-pin or pusher-dog arrangements can be used to allow automatic switching (power or spur lines)

Generally used when long distance and high frequency moves are required

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16. Trolley Conveyor

Unit + Overhead + No Accumulate

Uses a series of trolleys supported from or within an overhead track

Trolleys are equally spaced in a closed loop path and are suspended from a chain

Carriers are used to carry multiple units of product

Does not provide for accumulation

Commonly used in processing, assembly, packaging, and storage operations

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Similar to trolley conveyor due to use of discretely spaced carriers transported by an overhead chain; however, the power-and-free conveyor uses two tracks: one powered and the other nonpowered (or free)

Carriers can be disengaged from the power chain and accumulated or switched onto spurs

Termed an Inverted Power-and-Free Conveyor when tracks are located on the floor

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18. Monorail

Unit + Overhead + Accumulate

Overhead single track (i.e., mono-rail) or track network on which one or more carriers ride

Carriers: powered (electrically or pneumatically) or nonpowered

Carrier can range from a simple hook to a hoist to an intelligent-vehicle-like device

Single-carrier, single-track monorail similar to bridge or gantry crane

Multi-carrier, track network monorail similar to both a trolley conveyor, except that the carriers operate independently and the track need not be in a closed loop, and a fixed-path automatic guided vehicle (AGV) system, except that it operates overhead

Termed an Automated Electrified Monorail (AEM) system when it has similar control characteristics as an AGV system

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19. Sortation Conveyor

Unit + On-Floor/Overhead

Sortation conveyors are used for merging, identifying, inducting, and separating products to be conveyed to specific destinations

19(a) Sortation Conveyor: Diverter

Stationary or movable arms that deflect, push, or pull a product to desired destination

Since they do not come in contact with the conveyor, they can be used with almost any flat surface conveyor

Usually hydraulically or pneumatically operated, but also can be motor driven

Simple and low cost

19(b) Sortation Conveyor: Pop-Up Device

One or more rows of powered rollers or wheels or chains that pop up above surface of conveyor to lift product and guide it off conveyor at an angle; wheels are lowered when products not required to be diverted

Only capable of sorting flat-bottomed items

Pop-up rollers are generally faster than pop-up wheels

19(c) Sortation Conveyor: Sliding Shoe Sorter

Sliding shoe sorter (a.k.a. moving slat sorter) uses series of diverter slats that slide across the horizontal surface to engage product and guide it off conveyor

Slats move from side to side as product flows in order to divert the product to either side

Gentle and gradual handling of products

19(d) Sortation Conveyor: Tilting Device

Trays or slats provide combined sorting mechanism and product transporter

Can accommodate elevation changes

Tilt tray sorters usually designed in continuous loops with a compact layout and recirculation of products not sorted the first time

Tilt slat sorters carry products on flat-surface slat conveyor and can handle wider variety of products compared to tilt tray

19(e) Sortation Conveyor: Cross-Belt Transfer Device

Either continuous loop, where individual carriages are linked together to form an endless loop, or train style (asynchronous), where a small number of carriers tied together with potential for several trains running track simultaneously

Each carriage equipped with small belt conveyor, called the cell, that is mounted perpendicular to direction of travel of loop and discharges product at appropriate destination

Automatically separates single line of products into multiple in-line discharge lines