To err is human
June 1st 2005

The cost of automated systems often deters companies from investing in them. But, when calculated against employment costs, the pay-back period is surprisingly short, says European Conveyor Systems Warehouse tasks such as order picking, stock replenishment, packing and despatch are often repetitive and physically tiring, but they are also absolutely vital parts of a successful distribution operation. This is particularly the case as the UK economy is driven increasingly by a next-day 24/7 approach.

Finding and retaining the right number of staff of the right quality to do this work – staff that arrive on time every day and work at optimum efficiency for eight hours – is very difficult. So it’s understandable that companies whose distribution operations are particularly key to their success or where the products make manual handling particularly arduous are increasingly turning to automated systems with scanners and barcodes to solve their problems.

Although the initial cost can seem high, the pay-back period when calculated against the employment costs can be surprisingly short, according to John Bower, managing director of Nottingham-based European Conveyor Systems (ECS). And the conveyor system always starts on time and is still working as efficiently at the end of a shift as it did at the beginning.

A conveyor system from ECS dramatically improved the efficiency and accuracy of order picking at the Hemel Hempstead warehouse of Waverley Vintners, a leading supplier of wines and spirits to the licensed trade.

The 12,000m2 warehouse stocks about 2000 product lines and despatches an average of 12,000 cases a day. Around 15 per cent of the cases contain mixed products, and these were identified as causing the most problems. Staff were often taking a long time to pick a small number of items, and at the busiest times they could also get in each other’s way. The company also wanted to increase picking accuracy in order to minimise returns by customers.

Split case orders are now carried on the ECS conveyor system, and staff walk no more than 20 metres to pick any item.

Orders are picked into cartons carried on plastic trays bar-coded with each individual order number. Scanners on the conveyor read this number, and the system then coordinates it with the details of the order held on the warehouse computer and automatically sends the tray to the stock zones where the products required are held.

Once all the items are on the tray, it goes to the packing area where it is checked, sealed and labeled before being sent on to despatch. A zero pressure accumulation conveyor and re-circulation loop control the presentation of cartons to the packing benches.

The relative inflexibility of a conveyor system compared to using staff is often a concern when automation is being considered, says Bower. But if the conveyor system supplier is involved early enough and is fully briefed about a company’s plans, a considerable amount of flexibility is possible.

‘For a start, many systems are modular, so if extensions or alterations are needed in the future we can almost always build them on to the existing equipment’, he said. ‘We never need to replace everything unless it is very old, and then it would not have the necessary reliability anyway.” When Cromwell Industrial Supplies opened a new 25,000m2 DC in Leicester in 2002 with an ECS conveyor system linking the ground and first floors, provision was made for it to be extended to the second floor in the future. This project was recently completed.

Phase 1 cost £600,000 and incorporated a 570 metre-long main conveyor which carried orders to the despatch area. Phase 2 serves the picking area on the third floor of the new building and has picking stations that are linked to the existing main system. Once a bin is full or an order has been completed, it is carried to one of the floors below on an automatic lowerator, which provides safe, controlled handling without using as much space as a conveyor. At order induction each order is married together with its own bar-coded tote bin, which is then routed along the conveyor system and through transfer units to the appropriate picking zones. When the pick is completed, the conveyor automatically delivers each tote to a specific checking and packing station within a consolidation area on the ground floor, determined by the final delivery address. Thirty packing stations are located at the end of five spur lanes off the main conveyor.

Overseeing the entire conveyor function is a SCADA (Supervisory Control and Data Acquisition) system designed by ECS to meet the exact needs of Cromwell and updated to monitor the extension on the second floor.

In a manufacturing situation sheer volume may not be an issue, but efficiency and safety may be, particularly if heavy or awkward loads are involved. This was the case at Johnson Controls Ltd, a specialist manufacturer of interior components for Jaguar cars.

Here ECS designed and installed a system for handling door casings without any manual handling, while maintaining accurate stock control. The casings are produced in four different colours in batches of 25 car sets at a time and are held in stock, ready for components such as door handles and switches to be fitted.

The ECS conveyor system is designed to carry special stillages, each holding six car sets, from the processing area to the door assembly area, transferring stock on a firstin, first-out basis as required. The stockholding area consists of 36 twin-strand chain conveyors on two levels, each capable of holding three stillages, with the different sections accessed by automatic transfer cars and lifts.

On the assembly side five take-off conveyors are provided for unloading door casings from the stillages, which are then recirculated automatically back to the processing area by a zero-line-pressure accumulation conveyor with powered rollers.

The conveyor system is controlled and the location of the stillages mapped by a PLC with a colour touch-screen operator interface, which also provides a colour selection facility and inventory data.

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