Published: 01 March 2011 12:00 AM
Industry Channel: Materials HandlingAuthor: Malory Davies
It's all a matter of choice, of course, but ensuring that you have the right picking system for your particular product needs careful thought. Malory Davies examines some of the issues.
The range of picking technologies on offer can be confusing - each has its strong and weak points depending on the operation. And the key to deciding which system is best, is to know your product and the picking requirements inside out. If you are starting with a bad system, making it go faster is not a good thing.
Ed Hutchison, managing director of Bito Storage Systems, says: "While manual picking processes will offer flexibility, once a critical limit is reached in terms of throughputs, automated picking systems come into the frame, particularly for operations that are large, require 24-hour availability, need to minimise personnel and demand high throughputs and pick accuracy. Automation offers the advantage of high density storage, predictability of operations and a competitive edge in terms of hitting service levels. However, the benefits of automation can only be realised when there is a good business case for automating a process, otherwise a company can end up with a system that lacks flexibility and will not achieve the envisaged throughputs to deliver a return on their investment."
Boots won a European Supply Chain Excellence Award last year for its new automated distribution centre at Nottingham. Witron was responsible for the automation at the Stores Service Centre which replaces four national distribution centres and 17 regional warehouses.
The picking system at the SSC consists of 180,000 tote locations and 39,000 pallet locations and supplies 2,500 stores. The article range covers some 30,000 different products. On peak days, Boots has the capacity to pick up to six million single pieces with Witron's dynamic picking system and car picking system. The picking systems enable family-grouped order picking that fits the respective store layout.
However, it is easy to overlook the basics, and Zetes business consultant Chris Hurst points out: "Paper is in some cases faster than using RF terminals as a pick process, but problems occur when data needs to be captured and entered because of the inevitable time delays and likelihood of errors."
Mike Alibone, business development manager, SSI Schaefer, says: "The accuracy of picking in goods-to-man systems can be improved by light guidance of the operator to a particular compartment in a storage/donor tote and by a series of lights confirming the pick quantity and where to place the item. A system is only as accurate as the product identification at goods receipt and put-away and the replenishment of stock to the correct picking location (whether man to goods or goods to man systems).
Hurst agrees that pick-to-light is very effective and works well for particular types of product groups. However, he says, it is inflexible by its nature if you want to change the layout of the warehouse. It tends to work best where there is consistent demand for certain product lines or fast moving lines that are core products.
Pick-to-voice arrived with a bang only a few years ago promising improved accuracy and productivity as well as the benefit of flexibility. This makes it straightforward to change the layout of a warehouse around fast moving, seasonal products, says Hurst.
Hutchison points out that Live Storage also offers a high density system for order picking. "You will see a small saving in personnel compared to automation yet the investment is relatively small so the payback period will be shorter - between three to six months. Integrating the Live Storage system with conveyors and picking technologies such as pick-to-light, pick to voice, barcode and wrist scanners will also increase pick rates and accuracy as well as provide a flexible system that enables a company to reconfigure its pick faces according to need," he says.
When considering a picking technology a company needs to consider what the cost of making errors would be and how important accuracy is versus productivity, says Simon Jones, UK sales manager at Zetes. "For instance, picking products for a production line will have a much lower error tolerance than order picking. For a supermarket, the priority will be speed over accuracy and so the solutions selected will reflect this. Again voice tends to win the comparison because it offers speed, accuracy and flexibility."
"Voice picking for instance is particularly beneficial in warehouses or stock rooms where the type of stock being picked changes frequently - so for retailers who are constantly introducing new ranges - fashion for instance, it is very useful," says Jones. "Argos is a good example of a company that would frequently reorganise its warehouse and uses voice for picking and put away."
However, before investing it's vital to stop and consider how the current picking process is working and how it measures up to what it should achieve, says Keith Edmonds, head of sales at Logistex.
Without knowing the cost and performance of the existing process it's difficult to assess with any accuracy Consider how the current picking process is working and how it measures up
to what it should achieve.what a supposedly improved system will deliver - or even whether the capital cost is genuinely justified in returning an acceptable ROI, he argues, and points out that the current system might actually be performing well. "We have recently seen manual systems still using a pick operative and trolley process that are achieving very high throughputs, thanks to well-designed pick configurations, the right fundamental disciplines in place and well-trained staff."
Edmonds also points out that the better the company understands the current system and has an efficient manual process in place, the more effective the new system is likely to be as it will be built on firm foundations. Logistex has developed an Excel-based program to help clients assess the long-term financial viability of a variety of picking and logistics schemes.
For organisations looking to improve their picking performance, the first step is normally to investigate upgrading an existing system. Bito's Ed Hutchison says: "Using every square and cubic metre in the best possible way is a challenge for both new and existing warehouses. Solutions to improve existing systems include using conveyors to support simultaneous working in zones, which results in a reduced throughput time; barcode scanning of products or locations in combination with a unique picking bin identification and paperless picking technologies such as pick-to-light or pick-by-voice.
"Improvements will also come by reducing the number of steps in a picking process to provide a more efficient solution; the more times a product is handled, the greater the risk of mistakes. Moreover, adding more steps in a process will inevitably take more time and management. Every instance of repetitive handling should be examined to see if it can be done faster or easier, or even be avoided.
"Where a FIFO system needs to be operated, switching to Live Storage will ensure FIFO without additional action required from the order picker because the items/cartons/bins/pallets are loaded sequentially per batch at the replenishment side. The articles are picked in the same sequence at the order picking side. Many operations are now dealing with a growing article assortment. In many cases, a larger number of references also involves less stock per reference," says Hutchison.
"Some simple solutions for this include: dividing a shelf by means of wire, wire-mesh or solid sheet dividers; equipping a container with pick opening and with cross or longitudinal dividers; dividing stackable euro-norm bins with insertable bins, divider strips and inlays. A multi-tier system is also a possibility, in that it multiplies the existing working surface by two or three times. An existing installation can also be reused on a mezzanine floor," he says.
Bart Riviere, Psion's director of speech solutions for EMEA, points out that implementing speech-directed solutions for warehouse processes is all about ROI, productivity improvement, error reduction and ergonomics of use for the end-user. Terminals can be worn, handheld or vehicle-cradled.
"When the existing process is redesigned to meet the objectives and the best ROI, either of these solutions is chosen or even a combination of them. Some processes will require multi-modal speech where the user is using speech only but sometimes combines this with screen/keyboard access or barcode scanning. A wireless headset gives the user even more benefits as he/she can leave the terminal vehicle-cradled. Wearing only a headset makes the information available to the user at the place where he/she needs it; for this reason we see a high interest and quite some initial successes of implementing speech in non-picking apps like put-away, replenishment, loading and so on," he says.
Critical factors that determine picking speed and accuracy
The aim of any picking operation is to be as accurate as possible and as fast as possible. Mike Alibone, business development manager at SSI Schaefer, says: "Identification is key to picking accuracy - picking the correct product is paramount to any successful storage and distribution warehouse operation. To achieve accurate picking the product must be correctly identified by barcode scanning products and/or location, or voice picking in which the operator has to confirm he/she is at the correct location by confirming a check digit.
When it comes to speed, says Alibone, warehouse managers should seek to minimise the distance travelled across the warehouse floor by its picking operators, resulting in less time walking and more time picking.
Ed Hutchison, managing director of Bito Storage Systems, also highlights the importance of ergonomics. "The pick face should be designed around the operative's natural picking curve so that fast movers are located at the best possible ergonomic height to pick quickly without bending and stretching. Presenting cartons or pallets at an angle will give the picker better access and an improved view of what's inside. Providing a rail to help pickers who are not so tall more easily access a higher pick location will also help."
Alibone points out that zones contribute to picking speed - picking locations located on a conveyor loop occupied and operated by a single operator who can work within a u-shaped cell (static based) or can walk with a trolley to pick from a range of locations in a small area minimises distances travelled. Storage type has a bearing on pick rate with carton live storage delivering higher rates of picking (along with lower frequency of replenishment) than standard shelving.
Adding pick by light to a shelving or carton live storage will also increase both speed and accuracy and has the advantage of being a hands-free operation. Goods-to-man systems are the most efficient in terms of operator speed (1,000 picks per hour can be achieved) and, when combined with light guidance systems, can also deliver an extremely high level of accuracy, he says.
Hutchison points out that stock-outs at the pick face can cause serious delay so you need to ensure there is an SKU available when the picker arrives at the location. This can be controlled by the warehouse management system; re-stocking in a timely fashion by deploying kanban, a two-bin system or by using Live Storage.
Another way to improve pick speed, he says, is by separating replenishment - which often involves lift trucks - from pedestrian picking. Live Storage helps here also, as replenishment and picking happen in separate aisles so the activities will not interfere with each other.
"Travel time for order pickers will be significantly influenced by the picking strategy, the arrangement of fast/slow movers and the choice of the storage technique. Dense storage systems can locate more SKU locations on a given footprint and thus reduce travel times compared to shallow storage, which requires long pick faces to accommodate sufficient numbers of fast moving SKU locations," says Hutchison.
Gareth Thomas, business consultant at Zetes, says: "As a rule of thumb, if operators are picking items from the pick face by hand then productivity and accuracy rates will be significantly improved by introducing voice-directed working. Conversely, if you are picking with materials handling equipment, there is a limit to the speed improvements achievable unless using AGV. In these situations the benefits to be realised are more ergonomic but no less significant."
Ultimately, says Alibone, robot-based picking will eventually become the preferred method of automated picking with "goods-to-robot" systems likely to be commonplace in the warehouses of the future.
Vanderlande in the zone
Vanderlande has been selected to implement a zone picking system for Fabory, the fastenings manufacturer, at Brno in the Czech Republic.
The current Brno warehouse is too small to handle the growing stock and turnover. Manual picking is becoming more expensive, because labour costs are increasing rapidly in Eastern Europe, so Fabory asked Vanderlande to design an automated system.
Based on customer data Vanderlande designed a Zone Picking System, containing 16 standard shelf pick locations divided over two floors. Six pick locations on the ground floor are also equipped with flow racks to replenish the shelves more efficiently. After order picking, the cartons are transported towards the shipping area for quality control, packing, automatic labelling and strapping and sortation. The capacity is 300 order cartons per hour. The system and process are controlled by Vanderlande's Vision warehouse control system, interfaced with the SAP host system. The project will start on site early 2011 and is expected to go into operation mid-2011.
Voice is choice for P&O Ferries
P&O Ferries chose voice-directed picking in its Dover warehouse to improve operational efficiency in partnership with Zetes to replace a system based on handheld terminals in ambient areas and paper-based picking within chilled and frozen environments.
Rob Meredith, head of supply chain at P&O Ferries, says: "Our original intention was to pick with handheld terminals throughout the site, but working in a freezer with handhelds and gloves is impractical and created an unwieldy process because pickers had to use paper initially and then input data once out of the freezer area.
"It was in the freezer where we saw the biggest improvements - both from an efficiency and ergonomic point of view," he continues. "Overall, we saw efficiency rise by some 20 per cent across the warehouse but this increased to 40-50 per cent in the freezer, even at temperatures of minus 18 degrees."
P&O's site combines a variety of environments and racking systems, all of which pose challenges to coverage and connectivity. In spite of this, the company has successfully used voice devices effectively in all areas of its warehouse.
Zetes implemented its 3iV Voice Solution with Vocollect T5 Talkman devices, which supports 29 warehouse operatives responsible for picking an average of 150 units an hour. LG CNS developed an additional interface between Zetes' 3iV voice and P&O's legacy Oracle eBiz system.
P&O Ferries has seen a 20 per cent efficiency improvement and greater efficiencies through sequentially ordered pick routeing and quality reporting. Errors have also been reduced, assisting P&O Ferries to achieve its 99.5 per cent accuracy targets.
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