This article discusses the applications, benefits, and construction of horizontal and vertical carousel conveyors.
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What are Carousel Conveyors?
The carousel conveyor (which is sometimes referred to as only a carousel) can be thought of as a set of “moving shelves" for industrial storage applications.
It is characterized by its “horse track" shaped conveyor belt arrangement - the total path of the conveyor belt looks like a horse track. The shelves or the bins are hinged with the conveyor belt in such a way that the bins can move with the belt without dropping the objects in them.
Some applications (like baggage handling systems at airports) don’t require separate shelves or bins to be attached to the conveyor belt as the belt itself carries the materials.
Two common configurations of carousel conveyors used across industry are the horizontal and vertical types.
The horizontal carousel has two conveyor belts run by a motor pulley and a conveyor belt idler, one running at the top and another at the bottom. The bins are placed in between the two belts by hinge joints.
In vertical carousels, the two belts run side by side and the shelves are placed in between the belts, again with the hinges.
In both the types, the bin with the specific part is moved to the picking station, where the part is picked up by an operator.
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When Should a Carousel Conveyor be Used?
Typically a carousel moves at a speed of around 1 MPH and a person can walk at a speed of around 3 MPH.
So you may think that rather than moving the conveyor, the operator herself can go and pick up the desired parts from the bins in a much faster way. Your calculation is right, provided there is only one conveyor used and that you ignore human fatigue.
In a more practical situation, multiple numbers of such conveyors are placed side-by-side and coordinating software is used for optimally moving the carousels.
Say, you need to collect five components from the five different conveyors. As the operator is collecting the first component, the required bin of the second conveyor is already moving toward the pick-up station and so on. As a result the overall efficiency increases.
Manual storage systems require larger areas and are less ergonomic. When using manual storage, the entire storage location needs to be illuminated and ventilated, but for carousel systems, ventilation and the illumination are required only at the pick-up stations.
Provision for advanced access control is made possible, especially through using the vertical system.
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Horizontal or Vertical - Which Carousel Conveyor to Choose?
The height of horizontal carousel conveyors normally goes up to twelve feet. Either an automated forklift or an industrial robot is used for collecting the items from the higher bins. The vertical conveyors do not require such an arrangement because the shelves are always at the operator’s reach.
The horizontal carousels can store more materials per unit volume in the bins or shelves. The reason for that is the longer bins of the vertical carousels have less support than the horizontal ones, and also the vertical carousels carry loads against gravity. Thus the horizontal carousel is more cost effective.
Another advantage of the horizontal carousel is loading flexibility: you can load just a few consecutive bins and keep the rest vacant as it will not cause a load imbalance. However, vertical carousels need to be loaded symmetrically.
Horizontal carousels move faster, so they are more efficient.
Emergency movement during power failure is easier for the horizontal carousels.
Vertical carousels have a smaller foot print and can go as high as forty feet. These types of carousels are normally covered with a sheet metal enclosure, so they also look better.
Humidity control or air conditioning of contents is easier in vertical conveyors.
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The carousel conveyor is used for automating the material storage and retrieval process mainly in industrial stores. The horizontal carousel is more efficient, energy effective, and flexible. However, the vertical carousel looks slim and requires less than half the foot print area with respect to the horizontal carousel. Also, equipping access control, humidity control, and temperature control systems is easier for vertical carousels.
The Logistics Handbook – By James F. Robeson, William C. Copacino, R. Edwin Howe.