Conveyor & sortation: Defeating downtime

The current demands on distribution centers are galvanizing facilities of all sizes, pressuring them to operate more quickly and efficiently. The rate of change has been swift, ideally keeping pace with advances in technology, the acceleration of the direct-to-consumer market, and the analysis of data. Conveyor and sortation systems are not immune to these forces; as the circulatory system of a facility, this equipment is being pushed to achieve unprecedented levels of throughput, accuracy and reliability.

These systems require moving the absolute maximum amount of product through a facility at every second of every shift while coping with mis-reads, jams, failures and maintenance. Each error or delay is certain to increase costs in labor, parts or lost customers.

The challenges of meeting more aggressive cutoff times to provide two-day or next-day shipping are compounded by changes in the types of items being handled. Conveyors and sorters are tasked with ferrying totes and cartons as well as handling poly bags, envelopes and items with increasingly diverse sizes and characteristics.

“Direct-to-consumer business creates a desire to mix all sorts of items with the cartons the system was initially designed for,” says Del Deur, vice president of distributor operations for TGW Systems. “Distributors want to ship and sort all those types at the very high rates that were easy to achieve with cartons. That presents all kinds of issues.”

Deur gives an example of how he recently ordered new tines for his rototiller, and the 20 pounds of steel arrived in a poly bag. “The bag was broken, with tines sticking out,” he says. “Someone had to transport that from packaging to the dock. How in the world do you convey that?”

Data, visibility and control
Data about conveyor speed, performance and status has always been available, but has rarely been subjected to higher-level analysis. In other words, conveyors typically run all day at top speeds, are serviced only after a failure, and have difficulty communicating jams and other hang-ups to anyone until the problem becomes big enough to notice.

“We’re now stepping into what we call analytics,” says Ken Ruehrdanz, manager of the distribution systems market for Dematic. “We’re taking all the information about each segment and zone and doing something with it that allows you to make predictions.”

Such tools are broadly classified as computerized maintenance management systems (CMMS), whose primary talent is measuring. According to Corey Calla, director of lifecycle sales for Intelligrated, a CMMS will aggregate data about hardware, making the management of conveyors and sorters an information technology discipline. Still, Calla has seen plenty of operations where systems are hanging on with duct tape and zip ties, although those who run it like a data-driven pit crew are becoming more common.

“The paradigm shift started five or six years ago when many customers put the materials handling system under the responsibility of IT groups,” Calla says. “Before, they never had any way to measure success. Now, you can tell the value of each asset and the cost to maintain, and which elements present the most issues or downtime. IT departments can then go to executives and make a case for why money is needed to keep these systems going.”

Translating raw data into meaningful information can become a powerful tool for boosting uptime, says Stephen Cwiak, senior vice president and head of subsystems for Interroll. Controls and software enable remote visibility or immediate notifications for technicians, self-generating reports and proactive service.

For example, if a scanner early in the system suddenly stops working, it might take a while for the issue to manifest itself. Cartons will keep recirculating and trying to read, and eventually the system gets bogged down. It could take one to three hours for the problem to balloon enough to be evident, Cwiak says, by which time a big manual project is needed to re-feed each carton.

“Some customers are using sorters to handle fulfillment, shipping and returns, which is so complex that the need for accuracy is even greater,” Cwiak says. “Where one error in 3,000 to 5,000 sorts might have been acceptable in the past, that is trending more toward one in 10,000.”

By monitoring missed scans as they happen, a CMMS can respond immediately. These systems can even signal for a replacement at 90% of a component’s life as opposed to waiting for outright failure. “CMMS collect and synthesize data beyond normal functions like scheduling maintenance,” says John Dillon, president of Wynright’s client care group. “Between monitoring component temperature, amperage and cycles, it gets into the realm of Big Data and pulling lots of different information together. It’s not an exact science, but those predictive capabilities are the next big focus.”

Update, upgrade or replace
There is plenty of aging equipment in use, and it goes without saying that the speed and capability of a new system can outpace its 30-year-old ancestors. But Calla says not all operations looking for improved conveyor or sortation technology need to start from scratch. “Just about any system out there can be outfitted with controls to make that connection back to a home base,” he says. “One customer with multiple sites, all 20 years old, can now see all six sites of operational data and maintenance data from a central dashboard.”

Central controls are great for the big picture, but modern systems also include a heavy emphasis on decentralization and access to data at points throughout a facility.

“Previously, some might have a screen at a merge area, or several screens throughout a system, but you would still have to walk up to screen and interface with it,” Deur says. “You might not even see an alarm of any kind without doing some digging. Applications can now send detailed information about a problem directly to a smart phone, where a technician can locate, diagnose and repair a problem—and even restart the system from the phone.”

Barron DeSanctis, executive vice president of business development and sales for SDI Group, emphasizes how electronic and mechanical upgrades provide valuable improvements to legacy systems. “Re-controlling” an existing tilt-tray sortation system with new software will probably not make it faster, he says, but it can provide visibility. Similarly, hardware alterations might not boost speed, but can help make much better use of a sorter.

“The addition of induction points on a 300-drop sorter can potentially move extra volume through the system,” DeSanctis says. “Say you have five induction stations at one side, and you’re moving 4,000 to 5,000 units per hour. Add another set of five induction points on the other side, and volume could potentially increase 33%.”

By combining physical improvements with an overlay of visibility and control, users can begin to better direct the performance of each component. Dematic’s Ruehrdanz points to a trend in automatic speed control in conveyor and sortation systems. “The traditional way is to set a system speed—typically the fastest speed possible—turn it on and run it all day long,” he says. “Very few applications need full speed at every second. There’s always an ebb and flow.”

Whether triggered by an operator or automatic, automatic speed control can be retrofitted on old systems and enables communication between neighboring zones. Conveyors and sorters can then throttle up or down based on the presence and volume of items coming through. Systems that don’t work so hard use less energy, are quieter and sustain as much as 50% less wear and tear. A sliding shoe sorter designed to run at 500 feet per minute, 24/7, might last 10 years. If the average speed can be reduced to 300 feet per minute, it might last twice as long.

For those starting fresh with a new system, it helps to anticipate future changes. Boyce Bonham, director of integrated systems and controls for Hytrol, offers the example of a customer who spent next to nothing to prepare in advance for additional diverts on its 400-foot sliding shoe sorter.

“We sized the drive to accommodate the additional diverts planned in the next five years, and it resulted in very little cost to make those changes,” Bonham says. “If we had not known, we would have needed a new drive, a bigger power service, and a much larger project.”

Even earlier foresight can yield big rewards, Bonham says. Many customers will wait until a system is installed and operating before training its operators. “Customers try to get a system in and up during a slow period, but when peak season hits, it’s the first opportunity for the system to get worked plenty hard—and it’s the wrong time to send maintenance staff out for training,” Bonham says. “There’s more time to train during the build stage, when a customer can even come to our facility to train on the actual equipment they will be using.”

Service, maintenance and uptime
Once a new system is chugging along, the trick is to keep it that way. In the past, operations were content with 94% to 96% uptime, and scanner read rates in the same range. According to Dillon, those targets are now 98% and above, especially for 24/7 operations and e-commerce operations. Since parts will inevitably fail, suppliers and end-users are working to minimize the downtime required for a changeout.

Common, repeatable parts limit the required inventory and might feature quick releases for swaps within 30 seconds instead of 30 minutes. Another trend is to establish modular subassemblies prepared as one part number. “The module might consist of 30 components, but in the system, it is just one part number,” Ruehrdanz says. “The 29 salvageable parts can be repurposed later back at the bench, but the total downtime is dramatically lower.”

Of course, that’s assuming the parts are on hand. As a supplier, Intelligrated’s Calla says it behooves him to regionalize the parts inventory so each site doesn’t need collections of all parts. “As they get more in-depth with CMMS, customers might also search other customers’ inventories and broker a deal if they’re only 10 miles away,” he says. “But you need to be careful that customers don’t rely too heavily on that system and start to think that they don’t need parts at all, because then nobody will have the part needed. That’s a balance, but it’s a model with potential.”

In the meantime, technical support services are emerging to endow an on-site technician with the knowledge of a remote expert. The expert can access the system, relay visual instructions on a display, and talk through the issue with whoever is on-site.

Dillon says it is also important for suppliers and end-users to communicate in advance of expected changes. Something as simple as a new carton size could see a mere 30% sort rate if the sorter isn’t designed for it. Whether done remotely or on-site, Dillon says lowering a photo eye, sending an extra shoe across a sorter to ensure a poly bag is successfully discharged, changing the pitch of a discharge chute, or increasing the gap between items can all help ensure closer to 95% successful sorts.

“If a customer tells us they know their system isn’t supposed to support poly bags, but a lot of them will be coming in the next holiday peak, we can take steps to prepare,” Dillon says. “Perhaps counter-intuitively, a slower sorter speed can often boost throughput for poly bags. Historically, these systems are put in and no one looks at it after that. Even if you have a system 10 years old, some of those little changes can make a big difference.”

Companies mentioned in this article
Dematic: dematic.com
Hytrol: hytrol.com
Intelligrated: intelligrated.com
Interroll: interroll.com
SDI Group: sdigroup.com
TGW Systems: tgw-group.com
Wynright: wynright.com