Conveyors: Gaining control, getting smarter
For decades, conveyor worked as a simple mechanical mode of product transportation. You could walk into a warehouse or distribution center and see lines of conveyor running product from here to there and there to here. Today, conveyor systems do more than just transport product, they support more sophisticated tasks to save time, space and energy for DC operations.
“The goal is always to move as much product as you can with the least amount of effort, people, capital, hours or whatever the metric, in order to get product to the right person,” explains Jerry Koch, director of corporate marketing and product management for Intelligrated. When it comes to delivering product, Koch says “it’s a race for the front door.”
But increasing throughput is about more than just running the conveyor faster. Some of today’s conveyor systems can run as fast as 600 feet per minute, but what operations are seeking from these systems is control and functionality.
“The good news is that enabling technology, such as conveyor systems, have evolved and form the foundation on which new high-performance automation is based,” says Ken Ruehrdanz, warehousing and distribution market manager for Dematic. “You need more technology, not more people.”
In fact, any time a person touches a product, not only is there a cost involved, but there’s potential for error, miscounting, mislabeling and misplacing product. “The beauty of automation is that it reduces the number of touches and gets the right product to the right person in the right condition,” says John Clark, director of marketing for TGW Systems.
Advances in software
Over the last decade, a key change in the materials handling sector has been a heavy shift toward the goods-to-person principle, explains Lennard Koppelmann, director of IT for SSI Schaefer. If a company analyzes its business model, it can typically come up with a fully automated, goods-to-person solution that results in fewer people and a better ROI, he says. The question then becomes: How can I achieve better throughput at the workstations?
One answer is software. The warehouse control system (WCS) has the intelligence and capability to control the conveying equipment while the warehouse management system (WMS) has the information about the product and orders that ride on top of the conveyor. With all components of the automated storage and retrieval system communicating together, product is sequenced onto the conveyor in the right order. The WCS communicates in real time and tells the conveyor where to divert, transfer and merge product.
Conveyor is laid out in a route that minimizes travel time, but the software makes the decisions about where product should go. “Software makes flow decisions based on the operations around the conveyor and what’s happening in a picking area,” says Intelligrated’s Koch. “Totes go to a divert, or transfer point, if there are things in it to be picked,” he explains.
In a goods-to-person picking operation, the conveyor is guided by software that allows for the highly coordinated task of lining up and transporting the containers with SKUs in and out of the pick station in the precise sequence at exactly the right time for fulfillment.
With such a highly coordinated task comes the need for a more robust WCS to manage the equipment. In other words, the more you automate activity within a facility, the more the WCS has to play a role and link the conveyor to all the other systems.
The goods-to-person strategy is considered part of the outbound process because it’s all about filling orders to be shipped to customers. But, the outbound operation can only be successful if you receive, store and slot product efficiently on the inbound side and move it with as few touches as possible.
Better bar code reads
The storage and slotting process starts with product being inducted into the system, which typically means having scanners to read bar codes. At one time, getting a good bar code read would acknowledge that product was on the conveyor. According to Clark, “The system intelligence has gone from ‘I see a box’ to ‘I see a box. I know what’s inside the box. I know where to send this box.’”
But to send the box on its way, the system needs a good read to capture the information. A fixed bar code scanning device located in the conveyor bed is used to identify product and send related information to the host system, which in turn directs product to the ideal storage location. In cases where a system is handling small items, more scanners might be added to the conveyor bed to make sure a small item isn’t missed.
In addition to positioning a system’s sensors in the conveyor bed, bar code reading technology can be located in a bridge frame around the conveyor. So, instead of one sensor, you have many sensors looking at the product from a number of angles, which ensures a good read before the conveyor moves the product.
In addition to placement, scanning equipment itself is improved. As technology continues to advance, devices are getting smarter. The devices have better accuracy and are getting good bar code reads. “Without a good read, an item would go to a reject line then manual intervention would be required to get it back in line,” says Chris Glenn, director of product technology for Hytrol. So, if the upfront devices aren’t good, there could be costly problems down the line.
Weighing and shipping
If the box is headed to the shipping area, smart conveyor can play a role in confirming order accuracy and determining the optimal shipping method. While we don’t often think about the weighing process as a function of conveyor technology, it’s become part of the process that keeps product moving along the conveyor without interruption. This streamlined process can save time and money while increasing throughput.
Here’s how it works: Once a carton moves out of the picking area, it is scanned and weighed as it passes over load cells located underneath the conveyor. The system captures its information from the bar code and sends it to the host system or quality check station.
“If the weight isn’t within the system’s defined boundaries for that item, we know something’s wrong,” explains Russ Devilbiss, sales manager for Carter Controls and chair of the Material Handling Industry of America’s (MHIA) Conveyor & Sortation Systems Industry Group. “In an order fulfillment application, you need to know right away if an operator made an error so the item can be pulled off the conveyor, corrected and manually put back into the system as soon as possible.”
While certain conveyor scale technology can handle product weighing 1,000 pounds, others are capable of detecting weights that barely tip the scale at 1/100 of a pound, or the equivalent of a single sheet of paper. According to Devilbiss, one little piece of paper can make a big difference if it’s not detected and cost money down the supply chain.
As the carton is conveyed down the line, collateral materials like catalogs and packing dunnage can be inserted before it’s sealed. Then it’s reweighed, rescanned and reverified so a shipping label can be printed and applied and the carton can be sorted according to the ideal shipping mode. “All of these steps,” Devilbiss points out, “are made possible by conveyor carrying the product.”
Running on demand
While order and shipping accuracy can impact a company’s profit margin, energy usage can impact its operating budget. “Energy consumption and the rising cost of powering a conveyance system is a significant line item,” says Dematic’s Ruehrdanz. “But technology is rising to the continuous demand from end users to squeeze cost out of the process.”
Back in the day, conveyor had one on/off switch, which meant it was either completely off or the entire system was running. These days, conveyor systems have decentralized control. This means the conveyor is configured into zones that are each equipped with a localized power source so that each zone can turn on and off as it’s needed to move product. As Schaefer’s Koppelmann explains, the conveyor is intelligent enough to know that if product on a conveyor hits a sensor, the next sensor turns on, moves the product, and so on down the line—meaning that each section of conveyor only runs when it has something to move.
The brains behind this part of the conveyor operation are so-called smart cards, which are small devices located in each section that provide localized control. “The advent of small unitized control panels, gives you a low cost way of actually controlling a small segment of conveyor,” says Michael Brown, industry and market director for Interroll.
Small indeed. Integrated circuit technology enables control panels to be smaller than ever. In fact, Brown says that “a control panel that was once the size of a phone booth can now fit in the palm of your hand.”
And now that unitized electrical controls can be mass-produced in factories, operations with miles of conveyor, or with conveyor that’s a permanent part of its building structure, can go through and update—even 10 feet at a time. As Brown sees it, there’s already a budget for electricity to power the conveyor, but after a retrofit and movement is controlled zone by zone, an operation could realize huge savings by using energy only when it’s needed to move product.
Conveying down the line
With evolving technology, companies can get more out of conveyor than ever before. Functionality has increased, ROI has sped up and the installation is faster and easier.
“As technology continues to advance, conveyor will play a role in improving operations,” Dematic’s Ruehrdanz forecasts. “It’s not an old age technology; it’s modern and supports new, sophisticated tasks that are being performed in today’s most current, state-of-the-art facilities.”
But state-of-the-art doesn’t necessarily translate into a larger facility, and it’s not just the big players that can benefit from smart conveyor. “Conveyors are becoming less expensive and have off-the-shelf solutions that offer major benefits even for smaller operations,” says SSI Schaefer’s Koppelmann. “If the math is right and the ROI is correct, everyone can benefit.”