Many years ago, picking, packing and shipping an order was a slow and error-prone process. Expectations were far lower, and the time it took to get an order didn�t seem to be an urgent issue in most cases. Warehouses were stocked with items, and workers bustled around carrying paper. Wages were lower, and warehouse space was not too expensive.
Elements of that era of order fulfillment had human involvement in every step, starting with taking orders and entering them into the punch card reader. There were no ergonomic or mechanized considerations back then. Retrieving the order from the warehouse, then weighing, packing and sealing it were physically exhausting and time-consuming tasks.
Today, most of us cannot fathom order tracking without a computer. And barcode labels? They didn�t even come into play until the mid 1970s, when barcode standards were developed. The automotive and grocery industries were the first to adopt this technology once those standards were developed. Needless to say, a lot has changed since then. Our society has taught us to want it faster, cheaper and, in many cases, fresher.
The global marketplace has increased competition, giving the consumer many more choices than in the past. Electronic, satellite and online ordering have made it more convenient to order and restock items. In this new economy, several analysts and vendors have noted that company size does not affect the fundamental need for improved efficiencies.
Years of innovation have resulted in new challenges for distribution and warehousing. Increased numbers of orders meant increased system and facility throughput and required more resources and inventory tracking enhancements in order to fill those orders in a timely manner. Increased choices for the consumer meant more items to be stocked, thus taking up more warehouse space. These days, warehouse space and labor are at a premium.
A system integrator can be brought to the table to assist in controlling rising labor and distribution costs by enhancing existing systems, proposing new designs and developing simulations of a new, mechanized approach. He can also offer ideas for eliminating congestion in the receiving and shipping areas, coordinating material movement throughout the facility, eliminating bottlenecks and minimizing delays. All of these improvements serve to increase throughput and make better use of these valuable warehouse resources.
Of the many warehouse and distribution functions and processes, it seems that order picking tends to get the most attention. There are three primary objectives to consider when designing an order-picking operation: productivity, cycle time and accuracy.
Picking productivity is measured by the pick rate, which is basically how many pieces, cases or pallets can be picked per hour. Efficiency gains are usually in the form of reducing the travel time between picks. Cycle time is simply the amount of time it takes to get an order from order entry to the shipping dock. Regardless of the type of operation you are running, accuracy will be the primary objective. Technologies that help increase picking accuracy include pick-to-light systems and barcode scanners. Additionally, employee training, tracking accuracy and accountability are essential to achieving high levels of accuracy.
Automated vs. Manual Systems
Automated picking systems provide the ultimate in speed, capacity and accuracy for the picking process. An automated picking design can eliminate the requirement for sophisticated strategies commonly found in manual approaches such as wave management and intelligent slotting of stock keeping units (SKU).
Manual picking systems achieve many of the same goals as a fully automated solution but incorporate manual handling and control of the picking process. These systems are typically referred to as �pick and pack� systems. There are several types of picking processes.
Piece Picking � Also known as broken case picking, piece picking describes systems where individual items are picked. Piece pick operations usually have a large SKU base in the thousands or tens of thousands of items, small quantities per pick and short cycle times. Mail order catalog companies and repair parts distributors are good examples of piece pick operations.
Batch Picking � As its name suggest, batch picking is a picking method where orders are grouped into small batches. The order picker will pick all orders within the batch in one pass. The batch is later sorted by order and/or delivery address. Batch picking is economical for large numbers of slow-moving items and ideal for broken-case and small-parts applications. Batch picking is usually associated with pickers that have multi-tiered picking carts, moving up and down aisles picking several orders at a time.
Zone Picking � When zone picking, every pick module is divided into several zones. Order pickers are assigned a specific zone, and they only pick items from within that zone. A conveyor system is typically used to move the cartons or totes from one zone to another. A fixed barcode scanner reads a pre-affixed barcode on the carton or tote; this barcode data is used by the conveyor system to send the carton or tote to zones where picks for that order are required. (Other zones are bypassed to speed the process.) Once an order is complete, the carton or tote is transported through weigh-in-motion scales to automated pack and seal machines while still on the conveyor. This type of picking is most effective in large operations with high numbers of SKUs, high numbers of orders and low to moderate numbers of required picks per order.
Wave Picking � Wave picking is a variation on zone picking. Rather than orders moving from one pick zone to the next, all zones are picked at the same time, and the items are later sorted and consolidated into individual orders. Wave picking is the quickest method for picking multiple-item orders. However, the sorting and consolidation process can be complicated.
Picking Technology
Installing picking technologies provides a means of automating the order-fulfillment process. Picking technologies come in many forms including, but not limited to, horizontal and vertical carousels, pick list, pick-to-carton, pick by label, pick-to-light, RF-directed picking and voice-directed picking.
Carousels � An efficient means of storing many smaller items, carousels can increase storage density and throughput in the facility. High-density vertical carousels can reclaim up to 75% of floor space utilizing otherwise wasted overhead space. They also make better use of labor resources as all items are brought to the operator with a push of a button. This can result in the elimination of up to 60% of an operator�s walk and search time. Items can be slotted, queued and batch picked to make best use of carousel rotation time.
Pick List � A picker gets her pick list from a host system or WMS. She races about the warehouse with her cart and paper pick list, collecting items for an order. Once the order is completed, she drops the cart at a shipping area and proceeds to her next order. These applications typically do not have many SKUs from which to choose.
Pick-to-Carton � Pick-to-carton logic uses item dimensions and weights to select the shipping carton prior to the order-picking process. Items are then picked directly into the shipping carton. When the picking is complete, dunnage is added, and the carton is sealed, eliminating a formal packing operation. This logic works best when picking and packing products with similar size or weight characteristics. In operations with a very diverse product mix, it�s much more difficult to get this type of logic to work effectively.
Pick-by-Label � Pick-by-label can be a value-added process in the manufacturing and assembly operations. The delivery of parts to the assembly lines is streamlined by increasing the efficiency of labor and permitting just-in-time delivery of the correct components in the correct quantity.
Pick-to-Light (PTL) � Picking productivity increases by up to 50% over paper pick list methods when using pick-to-light. Most pick modules and pick-to-light systems are configured based upon the type of product being processed. Users start the pick process by scanning an order barcode that is generated by the PTL system host. Generally speaking, bay lights direct the picker to the required pick area. Numeric displays indicate the location and quantity of the product to be picked. The user picks the items into a carton or tote until the process is complete at that pick area. The carton or tote is then placed on a take-away conveyor and generally runs throughout the module and ultimately to the pack and ship area.
RF-Directed Picking � Designed for multiple bins, totes or boxes, RF picking is also used to pick large or non-conveyable items. It enables batch-style picking of multiple orders during a single pass through the warehouse. Pickers typically use handheld wedge scanners for RF picking. The wedge scanner�s display directs the picker to the appropriate picking locations and does so in a logical sequence. Once the item is found, the operator scans the barcode on the item. This scan is read by the RF terminal and marked as complete. The picker gathers the items and proceeds until the RF terminal advises that each order is complete. RF picking generally results in high-picking accuracy.
Voice-Directed Picking � Voice picking is emerging as the technology of choice for hands-free case picking in the grocery and food service industries. It gives the picker a two-way dialog via a transmitted signal with a central data server for pick assignment and pick confirmation. Pickers do not have to interact with a computer screen, keyboard or scanner. They can talk and walk at the same time. Industry studies show picker productivity and pick accuracy levels actually increased 10% to 25% with voice picking technology. Voice technology is an established and stable technology that delivers impressive benefits in terms of speed, productivity and accuracy.
Sorting Technology
A good pick system is only part of the picture. All of the elements in a distribution center or warehouse have to be equal in performance. Order consolidation, sorter type and packing operations are equally important to the overall facility throughput and can be accomplished with many different types of technologies. A couple of the most recent types are tilt-tray and cross-belt sorters.
The tilt-tray sorter is a high-speed, bi-directional automatic sortation system capable of handling small carton merchandise, soft goods and other difficult-to-convey products to order bins. Usually configured in a loop, it can process from 3,000 to 9,000 pieces per hour. The basic design of a tilt-tray sorter consists of a carriage with a tray device mounted on top that is pulled through an enclosed track at a high rate of speed.
The cross-belt sorter features a powered belt conveyor on each carrier that moves products on and off in a predictable manner. As a result, it achieves positive sorting, faster line speed, an increased sort rate, narrower off-loading chutes and more off-load chutes concentrated in a given space. The cross-belt sorter is capable of handling a typical rate of 17,000 items per hour.
Future Potential
It�s likely that there will be a huge reduction of human order pickers within several years. All picking and packing processes will be automated. A series of cartons would be assembled and have a label put on by machine. The main system controller would know which order the cartons are entering the system, so it would have the automated picking system have the items queued on the pick conveyor that go into each carton. The carton would be stopped at the packing station, and a pick-and-place robot or a dedicated packing machine would load the items. The carton would pass over an RF or CCD scanner to verify the correct items are in the carton. It would then proceed to an automatic void-fill and taping machine and finally to the shipping area. The main system controller would send the orders to the system so that the cartons would be in the correct cubing position to go onto a pallet. A robot would load the pallets. The pallets would be sitting on pallet conveyor, which feeds directly into the trucks at the shipping dock. Packing and taping methods would also become faster and more environmentally friendly.
Barcode labels and related technologies will probably fade away and RF identification tags will come of age. The growing acceptance of RFID tags across a range of industries is one of the major reasons for their strong projected market growth. With such a device, the RF chip and antenna are affixed to a tote or carton or directly onto the manufactured goods. The tiny device is then programmed using a fixed or handheld RF scanner. RFID tags go beyond the simple barcode identification method normally associated with this technology. Each tag is uniquely identified and can hold a plethora of information. Taking that concept a step further, GPS and satellite technologies will no doubt become essential in this industry for tracking and inventory purposes.
What are the elements that will be key in the advancement of order picking? As an in-depth analysis of a facility�s inventory and storage needs, inventory profiling stands far above any other factor. Based upon specific need, profiling can further be used as a basis for overall planning, modeling as well as setup. The profiling program can include analysis by activity, zone, package type or SKU. With so much potential for growth, the future looks exciting.
Joel A. Bos is the director of Controls and Software Engineering at DPI Material Handling Systems. For more information, call 616-531-2250 or e-mail jobs@dpisystems.com.
