While the job of parcel shipping and distribution remains essentially the same, conveying and sortation technology evolves to keep pace with the demands of the modern distribution center. This second part of a two-part series discusses some more of the latest trends in the field.
No two material handling projects or conveyor installations are the same the process is unique to each distribution center (DC). While a large retailer like Target might have thousands of SKUs in a DC, for example, a smaller DC operation might have only 200. Where Target might pick by the carton, another operation might pick by the split-case. These variations make the movement, accumulation and sortation of products 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, products 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 many ways that newer material handling systems accommodate system stalls is the use of variable speed drives, particularly in distribution supporting manufacturing. These controllers enable conveyors to run at variable speeds so their speeds can be increased or decreased at any time, allowing a system to catch up or decelerate to maintain 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. For example, if a packer is putting products into cardboard boxes, obviously the plant doesnt want any equipment on the line to stop, explains Bryan Boyce, Product Manager, Case Conveyor Products, FKI Logistex North America. 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 products through the palletizer. They were so focused on the upstream problem that they didnt 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, he notes.
Control Remains the Key
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
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 products out the door.
The RFID Control Question
RFID is the buzzword in DC material handling controls. Mandated by Wal-Mart and the Department of Defense, RFID is slowly making headway as a way to increase visibility in the DC and the whole supply chain.
With lessons learned from RFID implementations in the 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.
As the cost of RFID tags comes down and the technology further penetrates the market, material handling equipment will increasingly make direct use of the technology, as will the control systems that must support the volume of data that RFID provides.
This Way, That Way
In the parlance of material handling, basic merge and diverge conveying is considered the poor mans version of automated sortation. While the conveyor does the dirty work of getting products to the sorter, todays advanced, high-speed sortation systems are truly the heart of the most successful DCs.
Whether its for item or container sortation, a number of sorter styles and prices are available from tilt-trays and cross-belts to sliding shoe and linear belt sorters. The latest innovation, the linear belt sorter, uses a series of belt modules to drive product through sortation. It also handles a variety of product types, from bulk mail bags to CDs.
Speeds, throughputs and price tags vary from low-end sorters using pop-up wheels to high-end sliding shoe (linear) sorters. High-end linear sorters can reach speeds in excess of 700 fpm and throughputs of more than 300 cartons per minute, but their cost is several times greater than lower-end sorters.
These days, it seems that everyone wants to pump more volume through their doors, says Sean Hirka, Product Manager, Sortation Products, FKI Logistics. The retail sector is looking to improve its margins by reducing cost per case, so the more products that go out the door, [the more quickly] it goes straight to the bottom line. That leads to the desire for faster sortation speeds.
As with conveyors, the same concerns have guided developments in the sortation market noise, maintenance, throughput, modularity and efficiencies are chief among them. With current sortation technology approaching the basic physical limitations of its design, material handling vendors are looking to other industries for solutions.
A fundamental goal of the industry is to continually increase throughput, which typically includes an increase in speed. With the high speeds, however, comes an increase in noise. This leads to the current trend toward using alternative design methods and sound-dampening materials, Hirka explains.
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 con-veyor costing as much as 75% less than sophisticated 24-volt motorized roller conveyor, traditional choices often trump more advanced offerings in many settings, particularly in slower manufacturing distribution lines.
There is a tradeoff, however. Conventional conveyor is slow by the standards of many distribution centers, 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 like regional parcel market sort centers, the higher cost of sortation equipment, particularly linear sorters, may offer a competitive business advantage when compared to the speed, cost and inaccuracies of manual sortation. So, it is important to compare factors other than cost when choosing your equipment.
The End Game
In parcel shipping and distribution, how quickly, efficiently and accurately organizations can get packages out the door is the name of the game. Organizations that can logistically and financially make the investment in automated material handling methods like conveying and sortation can reap enormous benefits.
Organizations are looking at their logistics and supply chains as an opportunity to improve efficiency, and ultimately, their bottom lines, believes Steve McElweenie, Vice President, Sortation, FKI Logistics. Theyre 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. Theyre finding excellent returns on the investment in material handling systems. So if your organization is noticing a increase in production times and a decrease in products produced, it may be time to re-examine your conveyor and sortation strategies.
Bryan Boyce is Product Manager, Case Conveyor Products; Gary Cash is Vice President of Product Management and Marketing; Sean Hirka is Product Manager, Sortation Products; and Steve McElweenie is Vice President, Sortation at FKI Logistex. For more information on material handling systems from FKI Logistex, including conveying and sortation, call toll-free 877-935-4564 or e-mail firstname.lastname@example.org. Visit FKI Logistex on the Web at www.fkilogistex.com.