Rack and shelving: Supporting speed

Storage systems were once designed to do one thing well: Hold goods until they were needed. Recently, however, the hunt for speed and efficiency in the warehouse and DC has placed more emphasis on every step a worker takes and every cubic foot of unused space.

Because they touch every item that passes through a facility, racks and shelves are no longer built simply to be big enough. These systems are now designed to reduce labor costs, optimize available space, and react quickly to changing business conditions. The best racking and shelving systems are about more than providing a temporary home to inventory; they are about serving the specific profile of the stock keeping unit (SKU).

“Racking is connected more than ever to the promise a company makes to its customers and the target service levels required to fulfill that promise,” says David McLain, national account manager for Steel King, who cites the growth of the e-commerce market as a key influence. “Businesses need to get the product in, have it on the shelf for as short a time as possible, then ship it to the customer directly and much more quickly than they’ve done in the past.”

The growth of warehouse management systems (WMS), per-item visibility and next-day/same-day shipping objectives has prompted companies to think differently about how product is stored and retrieved. Instead of endless rows of selective rack, facilities are now designed with an assortment of storage and picking systems to accommodate pallets and eaches, seasonal items and daily sellers, large and small items, and everything in between. The choice of storage for each can make or break a facility’s efforts to speed up product movement.

The rack race
Traditionally, a warehouse might be filled with single-deep selective rack, which gives the impression of product accessibility since every pick face is open for business. In practice, this approach cannot keep up with customers’ desire for rapid order fulfillment, according to Carlos Oliver, president of Frazier Industrial.

“When you start asking about SKUs and volumes and movement, you start realizing you don’t store fast-movers the same way you store slow-movers,” says Oliver. “If you walk out into your warehouse and it’s filled with the same type of racking, you’re looking at an opportunity for improvement. You’re ignoring one end of the spectrum or the other.”

McLain agrees, saying he watched one customer replace a facility’s homogeneous storage system with a picking mezzanine with shelving, pallet flow in certain areas between six and 10 deep, high-rise shelving with narrow-aisle picking for individual parts, a carton flow/pallet flow pick module and four different profiles of selective rack for full pallet storage. In most cases, this type of transformation results in more work being done by fewer people in less space.

“There’s more competition for rapid order fulfillment and things like same-day shipping, and that impacts our industry,” says David Olson, national sales and marketing manager for Ridg-U-Rak and current president of the Rack Manufacturers Institute. Olson says rapid order fulfillment is an area of increased emphasis as companies attempt to compete with the Amazon model. “Easy access and highly efficient picking systems have become important, so we’re doing more pick modules in large DCs.”

Pick modules are increasingly used for the efficient storage and selection of cartons and eaches. As these modules grow in popularity, they’re also growing in size. Older style pick modules might have been replenished by forklifts, with a small center aisle and just one conveyor takeaway system, says McLain. “We’re now seeing much larger center aisles, 15- to 20- or 25-feet wide,” he says, “with four or five lanes of conveyor for both incoming and outgoing product.”

In many case-picking environments, staggered roller beds are replacing conventional wide roller carton flow shelves to accommodate rapidly changing SKU mixes, says McLain. Magnetic labels on the pick side and configurable lane indicators on the replenishment side make adjustments simple. “You have to be able to change from six SKUs on a shelf to 10 and change those out very quickly, he says. “Dedicated individual lanes hamper your ability to use 100% of your storage system. The carton flow industry and the picking of items are all becoming much more flexible.”

The desire to keep a single carton pick face as full as possible highlights the emphasis on reducing unused space. Wasted space results in a larger storage system footprint, which in turn impacts the distance a worker must travel to retrieve an item, both of which can increase costs. “Customers always had an appreciation of the impact of a storage system on their business,” says McLain, “but technology was the limiting factor.” Without granular data about each SKU, older systems drove a more traditional style of storage and selection, when the expectation was to ship in pallet loads and large cartons to the store. Individual items being shipped directly to the end customer has required big changes.

“Warehouse management systems are driving the whole process, and that seems to be the starting point for many companies,” adds McLain. “They’re wondering how that per-item visibility fits into what they want to do, and based on that, how they design a racking system to fit.”

Business intelligence
For some operations, racking might escape scrutiny as the focus hovers on WMS, lift trucks and picking technologies to cut labor costs, increase productivity and optimize slotting. Information technology is one piece, but storage systems that hamper the speed of putaway and retrieval, or result in too much empty space, will limit an operation’s potential.

“More and more, the intelligence is becoming important to the storage design,” says Alan Schneider, product manager for vertical storage solutions at Stanley Vidmar. “Knowing something’s location is essential to efficiency, especially if you have a dynamic system. Searching for and locating material is not very efficient, the idea of holding inventory ‘just in case’ is no longer sustainable, and visibility is paramount.”

The impact of business intelligence on storage optimization is exposing strengths and weaknesses of racking solutions that even their manufacturers could not have predicted. When Frazier launched its pushback racking, Oliver says the company thought it would be used for three- or four-deep applications. In recent years, he found it is almost exclusively double-deep, when a customer could get the same density for a lower cost with purpose-built double-deep. In the past, the decision would be simple; the same density with less expensive rack would win every time.

“Now it’s all about productivity,” says Oliver. “Pushback essentially operates the same as single-deep, without the need for pantograph lift trucks. The difference between running ‘single-deep’ pushback racking at 18 pallet moves per hour and double-deep reach racking at 12 means I can make up the racking costs in manpower.”

Analysis of business information can help a customer see the big picture, instead of prioritizing one metric, such as not missing a shipping window, at the expense of another, such as pallet moves per hour. Oliver says there are three legs of the stool when making decisions around racking: equipment price, the cost of the building space, and the price of labor, which can be inflated by as much as 30% with the wrong racking approach. For retrofits, the challenge is to work within limitations. But for new facilities, says Oliver, “the building should be designed to surround the best materials handling solution, not the other way around.”

Planning for the future
Only about 50% to 70% of new facilities are shaped around the materials handling system, says Oliver. In the planning of new facilities, rack and shelving rarely drive the discussion, even when the availability of space might have been a primary motivator for the new project. “People look at storage areas and say all it does is cost money,” adds Schneider. As we have seen, the cost of storage cannot be viewed in a vacuum, especially since the wrong system can increase costs long after it is installed.

In an effort to ensure flexibility in both short-term and long-term storage needs, more customers are designing with an eye toward future needs. “There are a lot of multi-phase projects and allowances for add-ons in the quoting packages we see,” says Olson. “People have been in the mode of only spending what they really know they will need, so they’d also like to be able to plan for anticipated costs. They’re looking further down the road.”

As a result, single-level picking modules are often designed to support the easy installation of a second, third or fourth tier in the future. Planned additions and expansions tend to be less disruptive to operations, especially as storage systems become more efficient and cube utilization approaches 100%. With optimized storage, it becomes more difficult to remove all the product, rip out the racking, and install an updated system, even if the cost of the racking is relatively small. The level of disruption in a world of same-day shipping would simply be too great.

New projects are also the time to consider the right equipment mix and how each tipped domino can impact another. Rack will need to interface with conveyors, lift trucks, people and software, and must be designed to optimize order fulfillment in addition to pallet positions in the cube. “With a new building, it’s an opportunity to design a storage system with equipment components that complement one another and align with the target process,” says Schneider.

Used racking: A cautionary tale
The longevity of racking equipment means it is likely to outlast the materials handling system it serves. When it’s time to consolidate or update facilities, it’s likely a large amount of perfectly good rack will end up on the used market. While it is often possible to find quality used rack, there are a number of factors to consider. According to David McLain, national account manager for Steel King, the specific properties of each rack installation make it difficult to find a used product that meets all requirements in a new application.

“You’ve got to be sure it meets the seismic standards for the region and the capacities of the application,” he says. “Used rack is rarely used for new picking systems, where the level of needed customization makes it just as easy and cost-effective to get the exact design direct from the rack supplier.”

David Olson, national sales and marketing manager for Ridg-U-Rak and current president of the Rack Manufacturers Institute, recommends the end-user contact a qualified design engineer to review the component metals and intended usage before purchasing used rack. Carlos Oliver, president of Frazier Industrial, takes it a step further, advising buyers to investigate the background of anyone in the business of selling used equipment.

“Used racking is a huge problem in the marketplace,” he says. “There are lots of small operations running around selling used rack, and they’re happy to take your money and disappear.”

Companies mentioned in this article
Frazier Industrial: frazier.com
Steel King Industries: steelking.com
Ridg-U-Rak: ridgurak.com
Stanley Vidmar: stanleyvidmar.com