Powered Package-Handling Roller Conveyor
18th May 2021
When it comes to moving packages and other relatively small items, two styles of conveyor dominate the market: belt conveyor and powered roller conveyor.
Traditionally, belt conveyor has been used for transporting products, while roller conveyor has been used for accumulating products.
Another factor taken into consideration when choosing between belt or roller conveyor depends on the size of the product being moved.
Belt conveyor
In traditional belt conveyor, an AC motor drives a pulley that then turns a long, looped belt. Underneath the belt sits either a bed of non-powered rollers or a sheet of metal known as a slider bed. The belt can be made of a variety of materials with a variety of surfaces, depending on the items it is intended to convey.
And, belted incline or decline conveyor can be used to move product from one level of a facility to another. Spiral conveyor is another way to move product from one level to another. If floor space is limited, spiral conveyors are often a good solution.
Regardless, traditional belt conveyor is a simple, time-tested technology. It’s less expensive than powered roller conveyor, it provides a more stable surface, and it can convey a variety of products. Poly bags, envelopes and electronics are examples of products handled easily by belt conveyor that are often too small or too light to be conveyed directly on rollers.
Roller conveyor
Despite the advantages of belt conveyor, many of today’s distribution centers are filled with roller conveyor because it allows accumulation of products. Accumulation is a way to make the conveyor store product for a determined amount of time then released into an automated sorter or palletizer, for example.
Zero pressure accumulation means products on the conveyor do not touch each other. Minimum pressure accumulation, however, allows the products to make contact, but with a determined degree of impact that will not cause damage.
Powered roller conveyor falls into a number of different categories, depending on the way the rollers are driven. Three common categories are line-shaft, belt-driven and motorized roller.
Line-shaft conveyor: In a section of line-shaft conveyor, a long metal shaft runs below the bed of rollers. Rubber o-rings connect the rollers to the shaft so that when the motor turns the shaft, the shaft turns the rollers.
Line-shaft conveyor is the least expensive type of roller conveyor. It has been in the market for a long time, but it has limitations. Even though line-shaft conveyor costs less, explains Don Erickson, director engineering for Automotion, it is parts-intensive, which leads to high maintenance requirements.
Belt-driven roller: Belt-driven roller conveyor is driven by a belt (usually covered with a rubber or plastic pad) that runs beneath the roller bed, perpendicular to the rollers. As a motor moves the belt, the belt moves the rollers. Belt-driven roller is a good accumulator because it’s easy to create zones. You can drop the belt away from the roller in any zone where you want to create accumulation.
Motorized roller: Motorized roller is also known as internal motor or motor-driven roller (MDR) conveyor. A section of motorized roller conveyor is divided into small zones. At least one roller in each zone has an internal motor that turns the roller. The rollers in each zone are connected to each other by rubber o-rings so that the turning of the motorized roller turns all the rollers in the zone.
The motors used in motorized roller are usually 24-volt DC motors. These motors use less energy than the motors used to drive other forms of roller conveyor and they provide less torque, making them safer, too.
Because each zone of rollers is powered independently, the zones can be configured to run only when a package is present. This on-demand feature increases energy savings even further and decreases noise—both are important factors when the end user is addressing economics and ergonomics.
Motorized roller doesn’t move as fast as the other forms of roller conveyor, because it’s a smaller, low-voltage DC configuration is designed to power only one zone, but it offers better product control and is easier to maintain.
This article comes from mmh edit released