There are several control technologies that can interface with existing or old technology. Five years ago, for example, manufacturers had thousands of wires extending from the PLC (programmable logic controller) to the field or each conveyor belt section, instructing each conveyor what to do and monitoring their performance. Technology advancements have virtually eliminated the need for all those wires, replacing them with just one Ethernet cable. By placing an IO (input, output) device right next to the conveyor system and plugging the Ethernet cable into it, manufacturers can extend the PLC’s reach or footprint.
A common objection of buying new technology is sometimes the high cost. However, the cost has been driven down to such a level that it now competes or may even be lower than conventional control technologies. For the same price, it also provides a longer lasting return on investment compared to conventional control technologies.
The benefits of new control technologies that can be used to retrofit existing conveyor systems include:
- Reduced energy consumption
- Faster installation
- Easier maintenance
- Enhanced diagnostics
- Distributed technology, which communicates with all conveyors on the plant floor
- Increased flexibility due to a building block approach
- Lower voltage, creating a safer workplace
Among the latest technologies that are gaining worldwide attention is one that’s specific to motorized drive conveyors or zero pressure accumulation conveyors.
These types of conveyors are typically found in facilities that need room for staging product until operations further downstream are ready to move product from one point to the next. Accumulation conveyors typically consist of a motor roller banded to several idler rollers to create a “zone”, which is a specific spot where products sit. As products pull up to a sensor, the senor detects their presence, then the logic control tells the motor to turn on or stop, depending upon traffic downstream.
Ideally, each piece on the conveyor system stops and moves in an orderly fashion, much like cars at a red light. The first car stops, followed by the second, third and fourth cars. Each car leaves some space between itself and the car ahead to avoid jamming or bumping into each other. When the light turns green, each car then takes off in an orderly fashion, one after the other.
This new technology is powered by 24 volts and controls two zones or drives two rollers. It offers complete diagnostics, total control and flexibility of programming. Likewise, it also saves energy because it only runs as needed.
The second benefit is that engineering and installation time is reduced. Many times, as IO cards are placed on the conveyor system, manufacturers are required to set dip switches and program each zone with existing software. Not anymore. With this technology, manufacturers can place it at the most upstream part of the conveyor, which is usually at the starting point, then press and hold a button for a few seconds. It automates the installation process and automatically configures zero pressure accumulation.
Challenges and Mistakes
When retrofitting a conveyor system, one of the biggest challenges is figuring out how long the process will take. Will it require one week, several weeks or several months?
Oftentimes, professionals up and down the supply chain mistakenly underestimate the scale of the project. When retrofitting a conveyor, realize that the system will be torn apart and production will stop. Depending upon the selected application or software and the number of motors involved, installation could take anywhere from a week to perhaps several months.
So it’s important to work with a company whose employees possess both the knowledge and skill set to develop a functional specification and realistic timeline for installation. Otherwise, manufacturers usually end up underestimating the amount of time required for installation, resulting in several problems. For instance, they may fail to reach monthly production goals, miss important shipping schedules, have employees on the plant floor with no work to do and create customer service nightmares.
Preparation is key. When retrofitting an existing system, every contractor or person involved in the installation must develop a very detailed plan so the project is handled correctly and on time. Otherwise, a one-week installation could easily turn into several weeks.
The latest trends in the marketplace regarding control technologies are distributed systems and building block approaches. Instead of having a centralized control panel, manufacturers can actually mount newer technologies out in the field, next to the machine or conveyor. The Ethernet cable connects newer technologies to a PLC, enabling manufacturers to have complete control over any and all zones. Because newer technologies are installed in the field, companies can continue adding on new technologies as needed, which explains why this is considered a building block approach.
However, if a new conveyor system is needed, make sure it is modularized. Any modular system allows companies to add on new technology to meet the growing demands of their business.
David Sellers is director of operations at Insight Automation, Inc. based in Erlanger, KY. The company employs a network of over 200 workers, providing products and custom solutions for material handling conveyor builders, system integrators and controls engineers throughout the world.
For more information, contact Sellers at 859-647-1111 or mailto:firstname.lastname@example.org
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