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Understanding accumulation technology choices leads to better solutions for operations

Understanding accumulation technology choices leads to better solutions for operations

Conveyor is conveyor. That might be the thought while touring a sophisticated distribution operation with miles of roller conveyor, but various technologies have many subtle differences in order to transport items with built-in accumulation functionality. Conveyor features and functionality can vary greatly by manufacturer and application, but in general, accumulation conveyors can be broken into three high-level categories – each with its own balance of throughput, control and investment level. Making the right selection requires careful consideration and understanding of the technologies and expected material flow through a system.  Conveyor is not always conveyor.

Medium-pressure accumulation

Medium-pressure accumulation conveyors typically utilize a flat drive belt to apply adjustable pressure to conveyor rollers without logical control of the accumulation function. As product starts to accumulate because of a stop in downstream conveyor, the drive continues to run and rollers underneath continue to turn, resulting in back pressure on accumulated products. Medium-pressure accumulation conveyors are typically most appropriate when handling same- or similar-size products that closely match the width of the conveyor. Product should also be capable of withstanding slight back pressure.

This constant pressure is equivalent to driving a car in traffic while maintaining slight pressure on the gas pedal - the car still powers forward after contacting the bumper ahead.

Medium-pressure accumulation conveyors often operate in facilities that rarely require accumulation, as too much back pressure can result in side-by-sides, item damage and jams.

Zero-pressure accumulation

Zero-pressure accumulation conveyors consist of rollers divided into zones that drop in sequence as products accumulate. The system uses a flat, narrow belt or padded chain as the drive mechanism, raised or lowered by pneumatic actuators to apply drive pressure to rollers and move product. As product runs downstream, pneumatic actuators release air to lower the drive mechanism and remove pressure on rollers, allowing the item to coast to a stop. Zero-pressure accumulation conveyors often operate in distribution and fulfillment facilities where the product mix consists of a wide range of sizes and weights.

Zero-pressure accumulation equates to releasing the gas pedal before colliding with stopped cars in front. As the car coasts to a stop, it contacts the one in front.

The ideal zero-pressure accumulation conveyors remove drive pressure early enough to prevent side-by-sides, jams or damage, but late enough to remove all air gaps between items. This maximizes the number of items along a given length of conveyor for optimum accumulation density.

Zero contact accumulation

Zero contact accumulation conveyors provide the best carton control and lowest risk of product damage by instantly stopping accumulation zones to prevent items from contacting each other. One method to power this type of accumulation is one or two motor-driven rollers (MDR) connected via o-bands to other non-powered rollers to control each accumulation zone. MDR conveyors use “run-on-demand” technology that provides significant energy savings, only operating when necessary to move product to the next zone. Other benefits include low operating noise and an inherently safer operation since the motor only needs to be large enough to power a short zone, rather than an entire conveyor.

Zero contact accumulation is most similar to how people normally drive. Cars only move forward when space in front of them is open and come to a stop before contacting the car in front.

The ideal zero-pressure accumulation conveyors remove drive pressure early enough to prevent side-by-sides, jams or damage, but late enough to remove all air gaps between items. This maximizes the number of items along a given length of conveyor for optimum accumulation density.

One example of an application that may be best suited for zero contact accumulation is an operation with bagged packaging. The logical operation of zero contact accumulation prevents items from contacting one another and overlapping, reducing the risk of problems and the need for manual intervention.

For more information on understanding the best accumulation conveyor for your operation, along with a comparison of each based on key criteria including throughput, back pressure, product damage and product-handling flexibility, read the Intelligrated white paper Selecting the right accumulation conveyor.