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Integrated Intelligent Warehouse Systems Boost Efficiency for Auto Parts Distributor

by Winn Hardin , Contributing Editor
Robotic Industries Association

Discount Auto Parts, Inc. (NYSE: DAP), one of the nation’s leading automotive aftermarket retailers, operates 660 stores in six Southeastern states.  At the end of 1998, DAP was rapidly outgrowing their existing 621,500 sq.ft. Lakeland, Florida distribution center (DC).  The company needed a new DC to relieve pressure on the Lakeland facility and cost effectively supply new retail outlets opening in Alabama, Florida, southern Georgia, Louisiana, Mississippi and east Texas.

To create this state-of-the-art material handling solution for a new Gallman, MS center, DAP partnered with the FKI Logistex Distribution & Warehouse team. By integrating the capabilities of palletizer specialists, FKI Logistex’s* (Danville, KY) Alvey Systems (St. Louis, MO); picker software and hardware experts Real Time Solutions(Emeryville, CA); and carousel supplier White Systems(Kenilworth, NJ), the Alvey integration team created a scalable, seamless order fulfillment and warehouse solution in 13 months.

Automating Auto Parts Distribution
The Gallman facility was designed from the ground up to fit the specific needs of DAP retailers. Because their stockroom space is limited, these retailers place frequent and diverse product orders. Discount needed a facility that could maximize storage space and efficiently build mixed orders to reduce store inventories through shortened delivery cycles and improved accuracy.  ‘‘We wanted to offer better service for our stores. The cost of inaccuracy is very high, especially for loss leaders during sales times. Once an order is delivered to a store it is prohibitively expensive to bring back to the warehouse,’‘ said DAP’s Peters.

The fastest way to improve accuracy and efficiency lay in automating DAP’s picking systems, said Real Time Solutions Account Manager Kim Baudry. During the design process, one of the most important hurdles was making the decision about which SKUs should be assigned to the various picking technologies. Discount found that over 35% of the case volume orders processed were comprised of only 15 SKUs while 28,000 other SKU’s completed DAP product list.

The FKI Logistex design uses five different picking technologies, including a robotic gantry with pallet-load carousels, picking carousels, a light-directed order fulfillment system, picking carts and an RF-based picking system. Real Time's Order Processing Software (EASYPICK â OPSv2.1) was used to provide a real time interface with DAP’s existing EXE Technologies (Dallas, TX) warehouse management system (WMS), while integrating and managing these multiple picking technologies.

At each of the five picking areas, at least two weeks worth of inventory are stocked in the forward pick area from storage pallet racks. Incoming orders from stores with similar orders are batched in quantities of 10 and then picked across the DC in waves. Real Time Solutions software OPSv2.1 provides the batch picking solution for the Gallman facility, providing a single, real time interface for the WMS. OPSv2.1 balances workloads, minimizes walk times, and increases overall order filling efficiency and accuracy by optimizing pick paths and stocking schedules. For example, OPSv2.1 allows the warehouse manager to see if there are picker delays and can immediately compensate by reallocating resources. In the past, this oversight responsibility would have required two or three supervisors.

Gantry Robotics Fills the Bill
Another area for improved efficiency lies in optimizing mixed pallet builds. Palletizing solution provider Alvey Systems designed a gantry robotic palletizing system to build mixed layer pallets. To feed the gantry, White Systems utilized pallet carousels equipped to store and move heavy-duty pallets.  This completely automated system saves valuable time, labor, and other associated costs.

According to Roy Martin, VP of Supply Chain and Logistics at DAP, ‘‘Gantry items are untouched by human hands and I really do believe the technology has a lot of merit for the relatively small number of full case items that make up a larger portion of our full case volume.  There are direct labor reductions and savings associated with heavy lifting, labor turnover, reduced training times and potential workers compensation exposure.’‘

The FKI Logistex system also automated full layer pallet builds. The 15 highest velocity items in the DAP DC are picked mostly in mixed pallet layers. This part of the picking system is comprised of three major elements—a set of White Systems pallet carousels, Alvey Systems 520 Series Gantry Robotic Palletizer and Alvey’s Order Manager, custom-built order management software—that combine to create a unique solution capable of building rainbow loads by layer.  Order Manager controls the 2500-pound per pallet multi-position carousels that buffer and position full or partial pallets of product for the gantry depalletizer/palletizer. 

Order Manager also manages SKU data and pick locations, enabling the gantry to pick pallet layers from the carousels and build a rainbow load.  As layers are picked from the pallet loads, and the carousel positions are emptied, the software alerts an operator to replenish the empty carousel position with the proper SKU.  The order management software then indexes the empty carousel position to the pallet in-feed where the operator loads a new pallet load of product for induction.

White Systems’ small carousel footprint allow a high volume of SKUs to be picked within a small gantry work envelope.  Operators can also use multiple positions for high volume SKUs to maximize picking efficiency.  By loading a single SKU in multiple carousel positions, rotation cycles are not as long, thus picking is more efficient. Directed by the Order Manager software, the carousels rotate pallets to the proper pick location within the gantry work envelope.

Once pallets are positioned within the gantry’s work envelope, a vision system located above the gantry captures an image of the incoming pallet load and feeds it to the gantry’s control system.  The vision system works as a safeguard detecting any shifts in the pallet load.  If a pallet load has shifted during travel from the manufacturer to the distribution center, the vision system directs the robot to adjust its position for proper depalletization. 

Traveling along the gantry frame, the robot stops at the designated location and employs its end-effector to pick a pallet layer.  The end-effector’s vacuum cups lift the layer, and its side clamps stabilize the load as the gantry transfers it to one of the multiple palletizing positions.  This process is repeated until the rainbow load is completed, at which point the load is discharged via a pallet conveyor.  The pallet conveying system takes the load through a fully automated stretch wrapper and a pallet labeler. The load is then discharged onto accumulation conveyors to await pickup by fork truck.

Small Footprint, High Throughput
Split-case order picking is accomplished for the 28,000 plus SKUs utilizing an integrated system of carton flow rack modules and 28 double-tiered White Systems bottom drive horizontal carousels. The highest moving 9,000 SKUs are stored in carton flow racks while the remaining 19,000 SKUs are located in the carousels. There are four carousels per pod. Each carousel is 8 ft. tall and consists of 50 bins with a capacity of 1,000 lbs. per bay. Each bay has 24-36 bins, depending on the size and velocity of each SKU. The carousel system delivers high throughput, density and accuracy for single SKUs, inner packs, and some small case items, said Terry Hinton, Systems Sales Manager for White Systems.

‘‘We introduced several different concepts that radically changed the design and gained a lot of floor space. The carousel installation comprised three levels, and squeezed in as many SKUs as possible. This design allowed us to keep aisles wide enough to accommodate more economical standard-sized forklifts,’‘ explained Hinton.

Split-case order picking in the carton flow rack occurs at one of two 400-foot long 3-level pick-to-light systems. The carton flow rack uses Real Time System’s EASYPICKâ pick-to-light technology -- a paperless fulfillment system that uses flashing lights to direct order fillers to the exact pick locations. To help ensure order accuracy, LED displays are used to show the order filler the correct pick quantity. Break pack items are put in totes that are then sent to the sortation system to be shipped—still in their totes—to stores. Pick-to-light is also used with full case items, which are placed directly on a sortation conveyor. Waist level placement of the conveyors in the pick-to-light areas increases ergonomic safety by reducing heavy lifting and also eliminates wasted movement, thereby speeding up the picking process.

Real Time Solution’s light-directed GO-Karts are used for special areas including potentially hazardous aerosol products and high dollar value components like car stereos. For these areas, the order filler scans a barcode on the pick ticket to identify a pick location on the scanner, takes a GO-Kart with 10 totes to the correct pick location. Items are then batch picked and put into totes based on light-specified quantities on each tote before moving on to the next scanner-identified pick location until the order is completed. In the RF pick areas, non-conveyable items and promotional store displays are located from scanning a pick ticket, put onto pallets and then moved by pallet jack to the appropriate shipping lane location.

While Gantry and RF picked pallets of items are staged directly to the shipping lanes, all other pick area types of product are placed on pick conveyors that connect with accumulation zones on the upper level mezzanines. From there, the products are merged, metered, and scanned onto an Alvey Unisort 10a flat slat shoe sorter that sends orders to the appropriate shipping lane for each store location in the batch of 10.  Toted and full case items are then stacked on the Gantry and RF pallets to fill out incomplete pallet layers in the order. 

At the finish line
Serving 150 stores at startup, the Gallman facility has the capability to ultimately serve 450.  The gantry arm also has the ability to pick from the top 27 highest velocity SKUs, expandable from the current program of the top 15.  The sortation system, with a design rate of 85 cases/totes per minute to support the current DC configuration, is mechanically capable of rates in excess of 200 sorts per minute and can therefore handle the output from a second building as well.

Overall, the financial investment in the Gallman facility had distinct advantages over a more conventional installation. The decrease in conveyor length required and carousel modules used and the corresponding savings in warehouse floor-space offset the additional expense incurred by the choice of the robotic gantry arm.

‘‘Between the Gantry system and the carousels, DAP was able to significantly reduce the operating space in terms of process and storage, relative to pick modules, racking and conveyor lengths,’‘ said DAP’s Peters.

The gantry system alone picks approximately 1100 cases per hour, a tremendous improvement over the previous average rate of 170 per hour at the Lakeland facility. Martin already sees a ROI on labor costs with the new DC.

‘‘After only a few weeks of full operation we have already found the design and technology has allowed us to reduce our original projected staffing levels by 29%,’‘ said Martin.  ‘‘The facility’s location has allowed us to offset up to $1 million dollars per year due to shortened truck routes.  We are currently fulfilling 25% of the Lakeland volume at what we feel are higher quality rates --- and what appear to be higher overall order-filling rates – a nice combination to have!  The icing on the cake is that the facility is operating at only a fraction of its ultimate capacity – and is designed to be more efficient as we add more volume – a very bright note for the future.’‘

*Alvey Systems, Real Time Solutions and White Systems are all wholly owned subsidiaries of FKI Logistex.

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