Conveying the meaning of efficiency
Casual passersby driving along Wolff Road near Medina, Ohio, would have no idea of the sophisticated technology behind one of the white barns that dot the landscape. If they slowed down to get a better look at the miniature horses in the paddock in front of the barn, they might also get a glimpse of the huge building behind it. They could see tractor-trailer rigs and smaller vehicles backed up to an expansive dock.
In fact, they'd be looking at the 120,000-sq.-ft. warehouse of Wolff Bros. Supply Co. If they were to step inside the warehouse, though, it would be easy to convince them they were in a kind of Tomorrowland for wholesalers. The warehouse is brightly lit, colorful, scrupulously clean and literally humming with activity. It even has a parade of sorts: plastic totes that wind their way along a conveyor system from a three-level mezzanine to shipping and will-call.
The conveyor and the division of the warehouse into seven zones are the heart of a highly automated order-fulfillment system. Although widely accepted in distribution in other industries, conveyors are still relatively rare in PHCP warehousing.
"The conveyor let us add to our mezzanine and still get the material down from the zones to where we need it," President Howard Wolff says. "A conveyor is really a set of mechanical legs to bring the material down for you. You can put people closer to where the material is, and you can serve the customer better and faster."
The ups and downs of warehousingThe conveyor snakes through the mezzanine from the top level, down to the middle level, back to the top, then veers sideways and down to the ground floor. Each of the three zones served has a drop point where material can be loaded onto the moving conveyor. The drop points are flanked by side lanes -- platforms that are at the same level as the conveyor and made of rollers for easy manual movement of heavy items.
The materials that can be transported on the conveyor are limited only by size. An individual item can be no wider than the rollers in the conveyor and must be able to make the turns. Bulkier, heavier items still have to be picked onto a pallet or a fork truck. Small items are placed in plastic totes that are about the size of a laundry basket. The totes are color-coded so that personnel at the other end of the conveyor can tell at a glance whether it's from the plumbing or electrical sections of the warehouse.
Picking carts are used for small but heavy items. The picker puts the tote on the cart and wheels it to the item. The shelf level of the cart is exactly equal to the side lane of the conveyor, allowing the picker to move totes or other materials onto the conveyor with little effort.
On one side of each tote is a reflective-tape target that can be read by a photoelectric reader at a "fork in the road" of the conveyor system. The totes are placed on the conveyor with the target facing toward or away from the reader, which determines whether the container will be sent to will-call (target facing the reader) or shipping (target on opposite side of tote).
The brain of the conveyor is a control panel housed in a cobalt-blue box. A schematic of the conveyor system on the front of the box illustrates the location of each drive, slave drive and motor. Green lights show that each element of the conveyor is functioning properly and, in case of a malfunction, exactly where the problem is.
Staying in the zoneThe most sophisticated conveyor system cannot provide peak productivity if the warehouse is not organized to take full advantage of it. Wolff Bros. decided that zone picking would prove to be the most efficient method for its operation. The company had looked at some other options. One was wave picking, in which the orders for the day are printed out and the entire quantity of an item for all orders is pulled at the same time. However, the Wolffs discarded that idea because the items have to be handled again when they are sorted into individual orders at the loading dock.
Another concept considered was the "here's-the-whole-order-go-get-the-stuff" approach. When a picker is done with the order, it's all together and ready to go on the truck. But when one man has one order in a 50,000-sq.-ft. warehouse -- let alone the 120,000 sq. ft. at Wolff Bros. -- he has to walk long distances, which is hard on both shoe leather and timely delivery.
"Zone picking is kind of in between wave picking and just going and getting the material," Wolff continues. "You're pulling an order, but you're breaking it up into the zones. It breaks the overwhelming into bite-size pieces."
Wolff Bros.' conveyor system covers Zones 1, 2 and 3, which comprise the warehouse's three-level mezzanine. Zone 4 is the rest of the warehouse, except for the specialized Zone 5 (the pipe-crane bay) and Zone 6 (the wire-cutting aisle). The yard is Zone 7.
The use of the conveyor and computer printers in each zone allows dispersal of the most commonly picked items; everything is still within a few steps of the order pickers. The A items -- those that move the fastest -- are kept close to the conveyor to minimize the number of steps the picker has to take to reach them. However, the A items also are spread throughout all seven zones to avoid pickers bumping into each other as they go for these big sellers. Thanks to the conveyor system, it doesn't matter whether an A item is upstairs and on the opposite side of the building from the shipping dock or counter. For picking purposes, it's still only 10 steps away from the conveyor.
The step-saving aspect of the zone system is one of its biggest benefits, Wolff notes. "About 90% of an employee's time in a conventional warehouse -- or about 90 cents of every payroll dollar -- is for walking. Only about 10% of the time does a warehouseman actually have his hands on the stock, which is what you are paying him for in the first place."
The picking aisles in Zone 4 feature a narrow-aisle system for heavy, bulky, hand-stacked merchandise. About 5 ft. wide, these aisles are packed floor to ceiling with material. Picking machines are used to reach and transport items. Once the machines enter an aisle, they are locked to its center, guided by a wire buried in the floor. The operator simply has to run the machine forward or backward, and up or down to the correct location. Because the machines are steered by the buried wire, there are no machine-shelf collisions.
Match a la modeThe company is just about ready to implement what it calls "match mode." While scanners have been used for stocking and cycle counts for several years, warehouse workers now use scanners to match the bar-coded labels that make up the pick ticket to the UPC bar-code labels on the items to be sure they're picking the right ones.
A scanner is actually a handheld computer that communicates with the AS-400 that serves as Wolff Bros.' main computer through the warehouse's radio-frequency network.
Becky Berger, operations manager at the Medina warehouse, says that match mode will make life in the warehouse easier. "Match mode is a simple procedure. The scanning gun tells the picker whether it's a good match, and the picker can go on to the next item."
Berger is appreciative of the fact that even novices will find the right product every time. "New employees really don't know the material they're pulling or putting away yet, but if they scan the wrong thing, the scanner tells them right away. Scanning catches labeling and cross-referencing mistakes, mispulls or errors in restocking."
The master ticket prints in either will-call or shipping; the bar-coded labels print in the zones. The pickers use the actual labels as their pick tickets, removing the labels from the backing and sticking them directly on the products as they pull them.
"If there's a shortage, the picker circles it on the label and leaves the label on the backing sheet," Berger says. "That way we know that item is a back order."
The capital outlay for a system as sophisticated as the one at his company would scare most warehousers away, Wolff admits. The conveyor system alone was between $120,000 and $150,000, while each of the six order-picking machines cost about $30,000. And those handheld scanners and the access points (RF receivers) with which they communicate took a $68,000 bite out of the cash flow. The original scanners are still being used in the branch warehouses, but the company has upgraded to newer technology at Medina when it had to buy more equipment.
However, Wolff believes that biting the bullet up front will reap dividends in the long run. The number of employees has dropped almost 20% since the addition of the conveyor system, while productivity (sales per employee) has increased by about 20%.
"The goal was to try to maintain or reduce the head count on employees through automation as our sales volume increases," Wolff says. "I think it was money well-spent."
SIDEBAR: ZAP! The order is pulled1. Wolff Bros.' computer system automatically breaks new orders out by line items. It then sends to each zone a pick order printed on labels ? one label per line item ? in the warehouse zone where each item is stored.
As the computer terminal in the zone prints out the labels, it also triggers a signal: A horn or bell gives a short burst, and a light starts flashing to alert pickers in the zone that an order is waiting.
2. With the labels in hand, the picker can quickly get the material onto the conveyor. The labels tell where each product is, and the shelves have locator labels for each product. A scanner reads the pick-order label and compares it with the bar code on the shelf.
Because the zone pick is printed in pick-path sequence, the picker is able to fill the orders with no backtracking. She pushes a picking cart through the aisles and places the ordered products into a plastic tote once she gets an electronic OK from the scanner.
3. After the picker scans the label for an item, she then scans the bar code on the product. The scanner alerts the user that she has a "Good match" or "Not a good match." If the match is good, the picker places the label directly on the product and loads it into a plastic tote or directly onto the conveyor. If the match is no good, she avoids pulling the wrong item.
4. Once the picker has loaded the tote, she slides it across the side lane and onto the conveyor, which will carry it to either will-call or the shipping department on the main level within three minutes.
The bar code will be scanned again at the shipping dock or will-call area. It verifies and finalizes inventory movement and closes out the order so that customer service can tell at a glance the status of the order.
5. A tote en route downstairs passes the diverter, a switchable arm that either lies parallel to the main conveyor to permit totes to pass on their way to will-call or moves across it to aim them toward shipping. The photo eye reads reflective tags on one side of the tote, which determine where the tote will be sent, and signals the diverter to swing into action.
6. An order that was diverted to shipping is packed and double-checked gainst its master pick slip. It is then sent on its way to the customer.
The conveyor and the zone system have cut delivery time for a will-call order in half or better, according to Howard Wolff, president of Wolff Bros.
"We're consistently around 15 to 20 minutes between the time a customer comes in and places an order and the time it's ready to be loaded," Wolff says.