Dock logistics: The final frontier of the modern warehouse
In just a few decades, automation, information and technology have transformed the warehouse from a simple storage space to an engine for company performance and growth. Processes throughout the modern warehouse bear only vague similarities to their counterparts from the 1980s. That is, until you get to dock logistics, which have largely escaped this evolution.
On the receiving side, labor is often thrown at the hodgepodge of incoming goods, which are typically staged in a huge area so they can be manually inspected, labeled and diverted as needed. Only when they have finished this time-consuming process are they released to, say, a state-of-the-art automated storage and retrieval system (AS/RS). Even the “touchless” warehouse often includes the caveat “once product has been received.” On the outbound side, efficient picking processes handle goods to within minutes or seconds of defined standards. Then that product sits at a dock, sometimes for hours.
As the final frontier in warehouse modernization, the spaces between the trailer and storage and between order fulfillment and the trailer have been overdue for an overhaul. “The biggest issues are related to inventory and time,” says Drew Hale, partner at The Progress Group. “The traditional dock has been under the presumption that there is inventory somewhere between the dock and storage and between the outbound truck and customer. It still is not unusual that if someone wanted to know what was in each of those trucks they’d open up the door and look.”
From slow to speedy receiving
Receiving has traditionally been a slow, labor-intensive process for a number of reasons. First, it is often not as important to put product speedily into storage as it is to pick it quickly and deliver it to the dock before shipping windows close. Additionally, the receiving dock acts as a sort of catch-all, where mislabeled products, order errors and other inconsistencies can be manually addressed before product enters a storage system.
“For 20 or more years, the conventional approach has been to load cartons onto pallets before they are moved and stored by lift trucks,” says Steve Schwietert, vice president of integrated systems sales for TGW Systems. “Receiving cartons has always been seen as a necessary evil that’s not very pretty. There might be three to five touches before a product even enters storage.”
As the slow setup for the more time-sensitive, pick-pack-and-ship operations, the receiving dock didn’t warrant much scrutiny until the rise of information technology. With visibility into what’s coming in each trailer, the best decision can be made to either direct products to storage, or perhaps bypass the entire putaway and picking process in favor of allocating inbound items directly to an outbound order. The concept of crossdocking can reduce touches, needed storage space and inventory. Of course, crossdocking requires software that bridges transportation and warehouse systems.
“Some have embraced making real-time decisions upon receipt,” says Schwietert. “Some are limited by software that requires product to arrive at a picking location before it can be allocated to an order.”
If there is 2.5 weeks of inventory in storage, inbound processing is not pressing. As organizations drive that 2.5 weeks closer to zero, then inbound becomes important. “Generally, people wanted to have 90% of what they received today available in inventory within 24 hours,” says Hale. “Now, the dock-to-stock target is more like four hours.” Such a facility requires less space, more dock doors and conveyors, and the ability to turn over trucks faster. New solutions support a rising movement toward just-in-time inventory patterns, especially in retail.
Automation at the dock
Speed at receiving can be enhanced with a new array of robotic truck unloading technologies and automatic guided vehicles (AGV). AGV forklifts and automated truck loaders and unloaders are increasingly at home in dock environments. The limiting factor for their adoption at the dock was the guidance technologies, which were challenged by the inconsistent conditions inside a trailer. Following advancements in perception, AGV forklifts can now roam from unloading to putaway to outbound deliveries and more.
Among the benefits of an automated dock is being able to track the product all the way into the trailer and validate that, says Darrin Peuterbaugh, account manager for Elettric 80. “Automation forces discipline into the process. Without automation, shipping and dock work is rarely subject to any sort of engineered standards.” When a product is loaded onto the trailer, that information is available immediately, which streamlines the business processes, he says. “Then you’re not relying on a person to update the ERP [enterprise resource planning system] or generate an ASN [advanced ship notice].”
In a facility with 30 or 40 dock doors, four or five AGVs could handle the loading. An AGV traffic management system allows sequencing, but it also allows an order to be interleaved, or split among multiple units, according to Peuterbaugh. Typically, with traditional forklifts, the orders are handled discretely, and productivity can suffer as a result.
The dock was a particular bottleneck in applications where cases are floor-stacked in trailers, according to Kerry Phillips, divisional president, engineering and integration, at Wynright. “The primary problem was that you could pick and process an order for an outbound trailer faster than you could actually load it,” he says. The latest robotic truck loaders/unloaders rival human speeds, but they do more than simply remove goods from the truck.
Truck unloaders can take on a variety of configurations to achieve everything from unloading to scanning, labeling, weighing and product routing. The mix-and-match options enable enhanced quality control and reduced labor, while allowing the customer to precisely balance manual labor and automation.
Labeling errors, for example, can be routed to a manual receiving station, but depending on the suppliers’ labeling practices that might be virtually a non-issue. “Across the board, there’s less concern a label will be applied correctly or survive the trip,” says Schwietert. “The predictability of carton-level labeling accuracy is now upwards of 90%, whereas 15 years ago, it was closer to 50%.”
The outbound buffer
To be efficient on the picking side, you want to keep the workload as level as possible. “But outbound shipping is not level, which is where the need for some sort of buffer comes in,” says Hale.
Ideally, an outbound shipment is sequenced by route stop, aisle-ready, or in some way loaded to make sure that unloading downstream can be made easier. However, because there is no way to guarantee the right pallet arrives in the right order, docks have traditionally included plenty of space for sorting and sequencing the order before loading. According to Tom Coyne, CEO of System Logistics, this is not terribly efficient in terms of space, labor or time; and truck turnover is often as much as two hours or more.
AS/RS buffers have been used to sequence pallets or cases and to release them in order, cutting truck turnover to as little as 10 minutes, and the required staging area to as little as six pallet locations. Coyne notes an example of a customer whose loading process was so efficient, the carrier agreed to have the drivers load their own trucks, creating further labor savings for the warehouse.
To achieve just-in-time shipping, the dock alone is not the only enabler of efficiency. If the upstream order fulfillment system can produce sequenced orders, then the dock needn’t concern itself with sorting random items. “It’s not shipping automation from the perspective of how you get the goods on the truck,” says Coyne. “It’s often about how you can support truck loading with a materials handling system.”
That said, Coyne believes an automated dock buffer can be done as a subsystem meant just to support shipping sequencing. “The shipping dock is a place where operators should focus for targeted investments, because of the combined benefits of labor and space savings,” says Coyne. “There are a lot of things we do in materials handling that give you one or the other. Automating the shipping process can get you both.”
Again, these systems are best deployed in operations with good visibility into inbound and outbound inventory and smooth coordination between warehouse and carriers. “What makes this an interesting strategy is that it doesn’t just affect what happens inside the four walls, but ends up being a supply chain strategy,” says Schwietert. “Otherwise, all that change and optimization inside the facility stops dead at the dock door, after which it’s out of their hands.”
Where is your dock?
The good news is that automated buffer systems often require less space than the traditional dock, making it a viable solution for retrofits. But this might be the time to consider whether you need a large, central dock staging area in the first place. Rob Schmit, executive vice president at Daifuku Webb, suggests sequencing does not need to happen in one place. Still, he appreciates the customers’ desire for a little wiggle room.
“Space is the key. The rest of the facility is jam-packed, with, ideally, every square foot optimized,” says Schmit. “But the dock is the one place where the facility has some room to breathe. As much as a customer might like trying to put in as much automation as possible, they also like to have some space, and nine times out of 10, that’s at the dock.”
The dock is a space where all of the shuffled incoming pallets can be sorted and sequenced. But why shuffle them at all? What if a pallet could go directly from the place where it was assembled to the trailer, in sequence? Schmit describes a series of small “pre-buffers” scattered throughout a facility where small quantities of product can be staged. A fleet of AGVs could then ferry the right item from the mini-dock to the trailer, in sequence and just in time.
“If you can push back the dock space into decentralized areas and guarantee the transport of product from those pre-buffer or end-of-aisle locations,” says Schmit, “you can reduce your dock size and put your space in locations that are of higher value to the organization.”
“The driving force has to be stated,” says Hale. “We don’t need much interaction between the warehouse and carriers if nobody’s going to drive us to be fast. If nobody says speed, it won’t happen. It’s changing, but it hasn’t yet changed.”
Companies mentioned in this article
Daifuku Webb: daifukuwebb.com
Elettric 80: elettric80.com
System Logistics: systemlogistics.com
The Progress Group: theprogressgroup.com