Come on a European Picking Tour
A European wayto handle material flow transforms warehouses into high-volume pickingmachines.
By LeslieLangnau, senior technical editor
Distributioncenters and warehouses are continually driven to handle increased productvolume more accurately. Unfortunately, managers at these facilities have notbeen able to do as much as they know is possible because they had to wait untilmaterial handling software and hardware capability caught up with the need. Nowit has, and managers are able to achieve 100 percent product selectionaccuracy, ship thousands of products per hour and do so without increasingstaff. In fact, in some cases, they've been able to reduce staffing needs by 50percent. The secret is to turn the DC or warehouse into a "pickingmachine" with automated material handling systems.
Recently, MaterialHandling Management had the opportunity to visit three distribution centers,two in Germany and one in Austria, to see firsthand how each transformed itselfinto a picking machine. A new automated picking concept, developed by Witron,has enabled these facilities to attain remarkable levels of productivity.Witron specializes in designing and building highly automated distributionfacilities, for both existing and greenfield applications. "Ourgoal," said Reinhard Boesl, managing director, Witron Germany, "is todesign and build highly efficient, automated distribution facilities that allowour customers to operate at the lowest possible cost."
Quick read through
The Libri bookdistribution center in Bad Hersfeld, Germany, started operation in June 2000.Viewed by many as the "Barnes & Noble" of Europe, it receivespallets of books from publishers, stores them in its warehouses, and fulfillsorders received daily from book stores and individual Internet customersthroughout most of Europe.
The greenfieldfacility allowed Libri to consolidate six warehouses into one. The new facilityholds about 300,000 titles, yet it takes only about 100 employees to pick up to40,000 books per hour. "We were able to design this type of facility now,because in the last four or five years the technology advanced enough to handlesuch product volume," said Harrie Swinkels, president, Witron, U.S.A.
This high rate ispossible through Witron's Dynamic Picking System (DPS). The DPS eliminates alllabor-intensive and non-value-adding handling steps through automation. "Alot of work is done up front to speed the picking process," said Swinkels."You can't always predict how orders come in, but you can change productarrangement to make picking easier."
When pallets arrivefrom publishers, employees break them down, repacking smaller quantities of thebooks into plastic storage bins. "Repacking compresses storage needs whilemaking product accessible to multiple picking workstations at the sametime," added Swinkels.
The plastic binsalso serve another purpose and are found in many DCs. In much of Europe,disposal of waste, like dunnage, cardboard coverings and shrink wrap, isheavily taxed. Distribution centers remove this waste and send product tostores in returnable plastic bins, eliminating this expense for the stores andthe end customer.
All bins have afixed bar code label on them. "These labels marry the bins with theircontents," said Swinkels. Then, they are conveyed to the bin storagewarehouse, and stored in one of 425,000 locations. These locations are servicedby 156 miniload AS/RS cranes. Maximum freedom of movement between the locationsand the picking workstations is necessary so that the DPS can automaticallyprofile and replenish the workstations. The Witron Inventory Management Systemsynchronizes and coordinates the location of every bin in the system. This is akey function of the DSP.
Every hour, anestimated 2,300 bins move through the picking area. Each picking area isconfigured so that nearly 80 percent of the picks are within one step of theworkstation. Thus, the average pick rate per picker is up to 450 picks perhour.
The miniload cranesdeliver the product bins from storage to the various pick slots throughout thesystem. The slots are part of the pick-to-light system that directs operatorsto remove books from the proper storage bins. The pickfront workstationcontains both static and dynamic pick slots. A-items are picked from staticlocations while B and C items are picked from dynamic locations.
The cranescontinually transfer B and C items between storage and the pickfront as needed.All orders are picked into order bins that are automatically conveyed to thevarious picking workstations.
While operatorspick books, printers generate product labels. Operators place these labels onthe back of each book prior to placing the books in the order bin.
The pickworkstation is equipped with a scanner that verifies the accuracy of the pick.A scale built into the workstation automatically weighs the order bin to ensurethe correct order quantity. Then the bin is conveyed to another pick station orto the shipping area.
As order bins movetoward the shipping area, an invoice is automatically printed, againcoordinated through the inventory management system, and dropped into the bins.The bins are then automatically sealed, and conveyed to the order consolidationarea where they are staged for loading onto trucks. Loading onto the shippingtruck is handled manually.
Pallets offast-moving or specialty books are stored in the high-bay warehouse, throughoutthe 9,100 storage locations. Very fast-moving books are usually picked frompallets. Three AS/RS cranes move up to 90 pallets per hour in and out of thispick area.
Most customerorders that arrive at Libri have six lines or less, for fewer than nine bookstotal per order. In fact, the majority of orders are for a single book. Fromthe time a customer order arrives, it takes about 2.5 hours to fulfill theorder and place it on a delivery truck.
Where bins go, andwhen they get there, is dynamically directed by the inventory managementsystem. This software handles all the routing and synchronization of conveyor,AS/RS movement, as well as orderpicking. Photoelectric sensors and bar codereaders along the conveyor lines provide needed data on what's going where.
The system operatesin real time — it's possible to take a bin out of sequence, and thesystem will quickly find it. As soon as the bin passes a reader, the WMS systemdiverts it to its destination. The inventory management system considerscustomer orders, storage maximization, picker performance and pick runminimization when directing product flow.
If a pick empties abin, the operator verifies that the bin is indeed empty and places it on theconveyor that runs behind the pick-to-light system. The bin then moves to anarea of the facility where it awaits its turn to receive repacked books.
If it's not empty,the operator can correct the quantity to the inventory control system throughthe pick-to-light buttons. This verification immediately updates the inventorysystem, which directs the crane to place it in a storage location.
Replenishment isautomatic. The inventory system simply directs the cranes to place the requiredproduct bins in the required pick slot.
Wels, Austria, ishome to SPAR, a national distribution center that supplies food to a network of1,500 stores located throughout that country. It was the first installation ofdynamic picking, operating since about 1998. Of the 60 people who work there,30 work in the picking area.
The DPS systemenables operators to make about 450 picks per hour, or 120,000 picks per day,with 99.9 percent accuracy. Presently, construction is under way to expand thefacility and bring in activities that are being performed elsewhere.
Palletloads ofproduct arrive by truck and by rail. Lift trucks place them onto one of fourconveyor entry points where pallet profiles and weight are automaticallychecked and entered into the inventory management system. Then the pallets areeither conveyed to the high-bay warehouse or to repack workstations where theyare broken down and the products repacked into storage bins.
The Witroninventory management system informs workers how many cases of each item can andshould be placed in a bin to maximize filling capacity. Although the operationis manual, workers achieve repack rates of 800 cases per hour at ergonomicallydesigned workstations. The bins are then automatically transported either tostorage or the picking workstation area by conveyors and AS/RS cranes.
"Because ofthe varying product sizes and types, it is more economical to use people forpicking than it would be to use automated equipment," continued Swinkels."The same is true for the repacking operation. The golden rule is not toautomate everything. Automation should only be applied where it serves as an economicreplacement of a certain operation."
A network ofminiload AS/RS cranes and conveyors bring product to 32 pick-to-light pickingzones. Although there are only a total of 2,700 pick slots in the entiresystem, pickers have access to all 11,000 SKUs through dynamic picking.
The pick-to-lightsystem guides operators to the correct bin, indicating the number of items toremove and place in the customer-order bin. Operators scan the picked item,which updates the inventory control system. Integrated scales at eachworkstation check weight of the order bin to ensure the right number of itemshave been picked for the order.
AS/RS cranes thenremove the bin and place it back into one of the 75,000 storage locations inthe warehouse. To increase efficiency, the cranes handle two bins at a time.
Grocery storeorders usually consist of multiple bins. Once a bin is filled, it's conveyed toan order consolidation area, where it awaits other bins designated for theorder. Then, all bins are conveyed to an automatic stacker where they arepalletized, banded together and conveyed to the loading dock. Operators usepallet trucks to load the stacked pallets onto trucks.
Roll 'em out
For automotivespare parts supplier A.T.U. in Weiden, Germany, Witron designed and built adistribution facility that employs only 90 people, operates with one shift andsupplies more than 40,000 items to a network of more than 300 stores andservice centers. During peak seasons, the number of shifts grows to 1.5.
Witron wasresponsible for the turnkey delivery and installation of the entiredistribution center including all mechanical components as well as the computersoftware, hardware and control technology. These included the PLC controls forthe cranes and conveyors.
In the facility isa 16-aisle pallet high-bay warehouse with more than 37,000 storage locations.There are 16 picking workstations that use the goods-to-man picking principle.The bin warehouse section has 10 aisles with more than 85,000 storagelocations.
Large parts arepicked in the pallet warehouse. AS/RS cranes transport parts from storage tothe pickfront area. Pickers then place the selected items in part carriersunder the direction of a color-coded pick-to-light, put-to-light system. TheWMS software routes pickers in such a way that employees do not cross eachother's path as they carry large, heavy parts. Employees can process 18,000order lines, or 55,000 picks, in one shift.
Small parts pickingis done in the front of the bin warehouse where miniload AS/RS cranes and conveyorstransport bins to picking workstations. A put-to-light system directs operatorsto remove parts from the storage bins and place a specific number in one ormore bins. Operators work on 20 orders simultaneously. This area of thefacility can process 22,000 order lines, or 56,000 picks, in one shift.
The semi-automatictire warehouse has storage for up to 600,000 tires on special carriers.Operators use lift trucks equipped with LXE radio frequency terminals thatindicate the order selection. Tire carriers are stacked vertically. When it'stime for replenishment, one of two reach trucks moves a tire carrier into anopen slot, as directed by the inventory management system.
German car ownerschange their tires with the seasons. Thus, order demand can go from 6,000 tirepicks per day to 33,000 tire picks per day.
Orders areautomatically consolidated on a per shipment basis through conveyors, transfercars and vertical lift stations. These systems move tire carriers, large-itemcarriers, bins and pallets to the loading docks. Lift trucks load these itemsto the trucks, which take them to various ATU stores.
Simple yet powerful
You might thinkthat the equipment used to transform these distribution centers was high-techand complex, but in reality, the devices were simple and involved basicback-and-forth motions. Most of the equipment consisted of pick-and-placedevices, conveyors, AS/RS cranes, photoelectric switches and verticalelevators, along with basic programmable logic controllers. The high-tech partwas really the software, with its synchronization and coordinationcapabilities. Thus, with thorough planning and basic elements, most DCs can betransformed into new "picking machines." MHM