Getting the right package to the right person at the right time and at the right price has always been the name of the game in shipping and distribution. While the mechanisms, technology and level of automation have evolved to change the nature of the game, the rules remain the same — quickly and efficiently process an order, convert it to a shipment, get it into the customer’s hands, and do it better than the competition.
Doing it better than the competition is not an easy task. Without modern material handling equipment and systems to streamline the process, the job of shipping and distribution would take a giant step backward. That step back would mean that an Amazon.com customer could wait weeks for his best-seller to arrive. The manager at a local Wal-Mart store might have to order his inventory months in advance. The global economy could crawl to a halt under the load of today’s order fulfillment volume.
Luckily, shipping and distribution managers have the benefit of automated conveying and sortation equipment to keep that from happening.
Drivers For Change
There are many drivers for change in material handling productivity, equipment and systems, including the demands of the Internet economy, the rising costs of energy, the high costs of skilled and loyal labor and customer expectations for fast and accurate order processing.
Perhaps the greatest force for change, though, is the movement to just-in-time inventory, with the many demands it puts on the supply chain. Moving product faster, more accurately and more cost-effectively is a requirement in today’s global economy, not a wish.
And while there have been few true innovations in conveying and sortation solutions in the last decade outside of the development of the linear belt sorter, material handling equipment companies have provided continual product improvements. Speed, throughput, efficiency, maintenance requirements, noise levels and power usage are areas in which improvements have been made to conventional equipment designs.
In many DCs, miles of conveyors required to move product from receiving to shipping translate to substantial noise, power usage, floor space and maintenance. They can also mean a long implementation time to get a new system or upgrade online.
One of the most important developments to address these problems is the recent move to 24-volt conveyor system designs. These systems eliminate the need for high-voltage power drops, consume significantly less energy, are safer to use, and produce much less noise than conventionally powered conveyor systems that rely on compressed air to drive rollers.
Modular systems are another innovation in the world of conveyors. Built in standard sizes and types and with standard parts and drives, modular conveyor systems shorten implementation times and speed replacement. Because one modular unit can be swapped out for another, system design is shortened and installation and repairs are simpler, reducing downtime.
Many Requirements, Basic Choices
A requirement for easy maintenance has driven change as well, and has spurred the use of belt-driven conveyors in place of chain-driven conveyors, particularly for accumulation. Because belt-driven conveyors do not need the constant lubrication that chain-driven systems require, they are increasingly used in DCs as a way to decrease maintenance hours and maximize uptime.
Belt-driven conveyors run more smoothly than chain-driven models as well, and advances in modular plastic belt drives have dramatically reduced maintenance times and costs. Similar advantages in maintenance are seen in conveyors manufactured with sealed gear reducers, which do not require regular lubrication.
Whether belt-driven or chain-driven, the choice between the two basic types of conveyor carrying surfaces—belt and roller—is largely determined by the nature of the item being conveyed. Hard-to-grip items in non-standard containers—or those with unusual packaging—call for belt conveyors, while conventionally boxed items can be easily moved using roller conveyors. In mixed-use environments, such as those in overnight and parcel delivery companies, belt conveyors are generally preferred.
“Parcel companies don’t require that their customers ship in standard box sizes or in boxes at all, so they need material handling equipment that is very flexible,” says Ray Guasco, vice president, parcel systems, FKI Logistex North America, St. Louis.
Today’s conveyor market is further driven by physical and financial limitations. Belt conveyors are generally less expensive than roller conveyors, for example, but require more drives to sustain conveying at longer distances. That means more wiring and controls, which ultimately affects cost, maintenance and noise production.
Speed and throughput levels are perhaps the ultimate technical hurdles. While most DC conveyors travel at moderate speeds until they ramp up to get to the sorters, the faster the overall speed of a conveyor system, the more product it can get out the door in a set amount of time. Today, speeds of 600 feet per minute and throughputs of 300 cartons per minute are common requirements for new DC material handling projects.
But speed is not the key, says Gary Cash, vice president, product management and marketing, FKI Logistex North America.
“The customer doesn’t care how fast his conveyor goes,” says Cash. “He actually wants it to go slower because it’s less noisy, saves energy and there’s less wear and tear. But he needs a certain throughput, and speed is one factor that determines that. As a material handling supplier, we have to make sure merges are efficient, that we gap product accurately, and that we generally optimize a system’s performance at the lowest possible speed.”
Heavy Loads
Particularly in manufacturing applications and supporting distribution operations, pallet load conveying is an important part of how goods move through a material handling facility.
“A lot of our customers are interested in reducing the need for forklifts to handle pallet loads,” says Mike Hale, product manager, pallet conveyor products, FKI Logistex North America. “They are looking for automated alternatives to forklift operation for a number of reasons, including worker safety, decreased maintenance and managing labor requirements. These alternatives can be found in pallet conveyor as well as automated storage-and-retrieval systems (AS/RS) that utilize cranes.”
Hale also sees a trend toward rainbow palletizing, an application in which pallet load stackers and articulated-arm robots work with pallet conveyors to stack and configure mixed layers of product. Pallet stacking enables better warehouse, cube and trailer space utilization, and fits both manufacturing and distribution settings where pallets are the major storage platform.
“Pallet conveyors for typical manufacturing distribution operations generally have weight limitations of 3,500 pounds,” notes Hale. “In heavier industrial settings, specially designed equipment, such as that built by our Custom Engineered Systems group, supports more robust loads.”
Other trends Hale sees are increased automation at the receiving and shipping docks using pallet conveyors, and pre-wired, plug-and-play modular conveyor systems for both pallet and conventional case conveying.
“One of the most beneficial features of plug-and-play is the ease of installation and reduced time it takes to bring the system online,” says Hale.
Finding The Right Conveyor
No two material handling projects or conveyor installations are the same. The process is unique to each DC. While a large retailer like Target might have thousands of SKUs in a DC, for example, a smaller DC might have only 200. Where Target might pick by the carton, another operation might pick by the split-case. These variations make movement, accumulation and sortation of product a completely different task.
Whatever the process, though, planning and staging conveyor transportation and accumulation are increasingly important tasks for material handling system suppliers. A system must be built to withstand hiccups, such as a sorter malfunction, and be able to play catch-up to meet desired throughput goals.
To accomplish this, the right mix of conveyor types and technologies is essential, as is a design that gives the system resilience. If the sorter goes down, product must have sufficient room to accumulate so that the conveyor system does not back up and force picking to be shut down as well.
One of the ways that newer material handling systems accommodate system stalls is variable speed drives, particularly in distribution supporting manufacturing. These controllers enable conveyors to run at variable speeds that can be increased or decreased at any time, allowing a system to catch up or decelerate in pace with potential upstream delays.
In many ways, the use of variable speed drives has required a change in thinking by material handling suppliers and DC engineers and managers, according to Bryan Boyce, product manager, case conveyor products, FKI Logistex North America.
“For example, if a packer is putting product into cardboard boxes, obviously the plant doesn’t want any equipment on the line to stop,” says Boyce. “When we design a conveyor system to take the boxes to a palletizer, the question used to be, if the palletizer goes down, how long can the packing operation continue to run until it has to stop to accommodate the delay in the palletizing area?
“What people neglected to consider was the time required to clear the resulting backed-up product through the palletizer. They were so focused on the upstream problem that they didn’t look at the downstream time needed to recover.
“In the past, the answer was to add more accumulation conveyor, increasing system costs. Now we see the prolific use of variable-speed drive controllers and more sophisticated controls on a reduced amount of accumulation conveyor. Manufacturing settings in which boxes are of a more consistent size through the line are more conducive to variable-speed drives and the variance in conveyor speeds that they allow. Generally, retail, e-commerce and other more conventional distribution settings still lean to accumulation as the solution,” notes Boyce.
Whatever the setting, supporting rapid and dynamic changes across the supply chain is the job of the material handling controls system. You can mechanically turn the chain faster or slower on a conveyor to vary its speed, but enabling the system to process additional information more quickly, more dynamically and more accurately is the function of the underlying controls.
Over the past decade, conveyor systems have gone through major changes in controls at the machine and system level. Onboard PLCs are much more sophisticated, as is the variety of PC-based control systems, wireless controls and other advanced systems that give DC managers the ability to supervise their equipment and make changes on the fly.
As systems grow in size and complexity, material handling vendors must build more sophistication and capacity into their control systems and networks. If a store in Atlanta needs an extra 25 boxes of goods, for example, is there adequate supply in the DC to satisfy that order? Building robustness into the controls system helps material handlers answer that question and deal with new situations quickly and accurately.
“The speeds we’re accomplishing today are faster than in the past,” says Cash. “We could always run faster by changing the gearing, but it’s the technology within the controls that enables us to see and move the boxes at a faster rate, much like your PC at home.
“Your PC gets faster and faster, doing the same things in less time. Likewise, the amount of real-time order and inventory information we can use and pass around the different distribution center networks allows us to make decisions faster and get more product out the door.”
RFID is the buzzword in material handling controls, and is slowly making headway as a way to increase visibility into the whole supply chain.
With lessons learned from RFID implementations in other markets, material handling vendors are increasingly adding RFID capabilities to their equipment. In conveying and sortation, RFID is still an adjunct, for the most part, with the capability for RFID tag reading and coding left at accessory readers, not built into the equipment. But, as the cost of RFID tags comes down and the technology further penetrates the market, material handling equipment will increasingly use the technology.
The Cost Factor
When all is said and done, the bottom line might be the ultimate factor that determines which direction to take in choosing a conveyor. With traditional belt- or chain-driven live roller conveyors costing as much as 75 percent less than sophisticated 24-volt motorized roller conveyors, traditional choices often trump more advanced offerings in many settings, particularly in slower manufacturing distribution lines.
There is a tradeoff, however. Conventional conveyors are slow by the standards of many DCs, so this less expensive alternative comes with a price in throughput. In high-volume facilities, cost is less important than the throughput needed to achieve distribution goals.
The same is true of sortation in these DCs. In smaller facilities, the higher cost of sortation equipment may offer a competitive advantage when compared to the speed, cost and inaccuracies of manual sortation. In shipping and distribution, how quickly, efficiently and accurately organizations can get packages out the door is the name of the game. Organizations that make the investment in automated material handling methods like conveying and sortation can reap enormous benefit.
“Organizations are looking at their logistics and supply chains as an opportunity to improve efficiency, and ultimately, their bottom lines,” says Steve McElweenie, vice president, sortation, FKI Logistex North America. “They’re using material handling automation to achieve better processing rates for their personnel and facilities. Material handling automation enables better utilization of assets, inventory and people. They’re finding excellent returns on their investment in material handling systems.”