The majority of case conveyor systems include at least some amount of accumulation conveyor. Typically, it is used for buffering and/or metering prior to sorters, switches, palletizers, robotics, and other decision making points within the system. While there are many types of accumulation conveyor, DC conveyor is becoming more and more popular for several reasons.

1. Energy Efficiency

On a DC accumulation conveyor, zones that are accumulated or in sleep mode do not run or use electricity. Also, on shorter AC conveyors, even a low horsepower motor can be overkill and an inefficient use of power. Conveyors that spend a lot of time with accumulated product can save significant amounts of energy improving the overall return on investment.

2. Easy Installation/Low Maintenance

Installation only requires mechanically setting conveyor in place and connecting driver cards and power supplies. There is no belt to run or splice or pneumatic lines to run. Since DC conveyor is powered by a low voltage, it can usually be ran through the conveyor side frames and doesn’t require rigid conduit. Along with easy installation, there are far fewer moving parts, which make diagnosing issues and replacing parts simpler and faster. Replacing a driver card or DC motor can take as little as 5 minutes. DC conveyor also requires less preventative maintenance since there are no gearmotors, bearings, or airlines to oil.

3. Quiet

DC conveyors whether band driven rollers or belted zones, offer a very low decibel level, reducing ambient plant noise. Choosing DC conveyor over AC conveyor can eliminate the need for required hearing protection. Typical DC operating conveyor runs between 65 and 75 decibels.

4. Safety

Since each zone only needs to have enough power to move one product at a time, DC conveyor motors only need a small fraction of the torque required for a single drive AC conveyor. This localized lower torque is much safer than a single power source with a belt that runs through the entire conveyor. While not completely eliminating the risk for injury, the chance of serious injury is much less common. Electrically, the lower voltage current used to power a DC conveyor produces a much less dangerous arc when shorted.

5. Flexibility

Because DC accumulation conveyors are basically independent conveyors, shortening or rearranging runs of conveyor is easily done without the need to splice belts or move drives. If a later application requires it, belts can be added over existing roller zones, rollers can be skewed, or speeds can be changed without changing a motor or wiring a variable frequency drive.

6. Handling

DC conveyors often offer built-in functionality to change speed, acceleration, and deceleration independently for each zone. Changing these settings can help solve problems with unstable products tipping or empty boxes coasting into the next zone. Increasing speed over several zones in a slug release mode can create a gap between products, eliminating the need for a standalone gapper.

7. Built in Logic

DC accumulation conveyor frequently uses driver cards with built-in accumulation logic. On basic, small systems it is not uncommon to get all of the functionality needed without the use of a Programmable Logic Controller (PLC). However, driver cards offer inputs and outputs that can communicate with PLCs to make a simple, hybrid system. Network-based logic cards are becoming a more common offering allowing easy access to the settings of the card and global changes to speed, jam timers, zone holds, etc.

Author: Matt Kohler