Automated guided vehicle (AGV) specialist, E&K Automation, has converted three Linde K-Range VNA (very narrow aisle) stacker trucks so that they move without drivers around luggage manufacturer, Samsonite’s new warehouse in Oudenaarde, Belgium. Working alongside operator controlled lift trucks, the computer controlled AGVs have transformed the efficiency of this busy European storage and distribution centre, as E&K’s UK subsidiary explains.
Moving along the narrow aisles following inductive guide wires set into the floor, the automated Linde trucks are fitted with an E&K laser-based navigation system so they can free-range off the wires into other areas of the warehouse. In this case, the trucks guide themselves by triangulation using reflectors mounted on the warehouse walls. Data communication between AGVs and the E&K controller is via a wireless LAN.
The trucks are also equipped with telescopic forks and pallet profile control, which checks that the dimensions of the pallets coming from production are correct and therefore that they can be stored in the automated warehouse.
Germain Ghys, a Samsonite employee with 28 years’ experience and currently logistics manager at Oudenaarde, commented, “Our ever increasing range of plastic suitcases and trolleys was becoming a logistical challenge.
“To cope with the multitude of products, we rented additional storage space in the immediate vicinity some years ago. However, this solution was not cost-effective, was too slow and inflexible, and in any case had reached its capacity.”
Samsonite products are split into fast and slow moving products. Every item can be a slow or a fast mover according to season and promotional campaigns, increasing logistical complexity. So in 2007, Samsonite decided that a new, dynamic bulk storage and order picking area was required for slow movers, primarily to release capacity for handling fast moving items.
Initially, three alternatives for the dynamic storage area were considered: first, a solution with fully automatic cranes; second, manually operated VNA trucks; and third, manually operated reach trucks. All three ideas were rejected due to the large number of trucks required and the high cost.
The search for further alternatives led Ghys and his staff to several companies, including E&K Automation. The experience and collaboration between E&K Automation and Linde Material Handling, underpinned by the reliability of the K-Range trucks, was one of the deciding factors behind Samsonite opting for this solution.
Additionally, the automated high bay VNA stacker trucks provide back-up in the event of electronic failure, as they are equipped with an operator seat and can be manually driven in an emergency. All of the other standard functions of the Linde lift trucks also remain. Simple maintenance was a further reason for choosing this solution. Furthermore, the availability on the Linde K truck of an interface that E&K Automation could readily use to access the electronics of the high bay VNA stackers allowed the trucks to be automated.
Construction began in the summer of 2008 on a greenfield site and was completed in April 2009. Samsonite did not need the support of a general contractor, because the company was able to use its own automation expertise.
“Without our own experience, it would not have been possible to carry out a project like this so quickly “, stated Ghys.
“All subcontractors, from the rack builder to the suppliers of conveyer systems, electrical networks and security systems as well as the automatic high bay stacker trucks were selected by us, while our in-house skills allowed us to develop our own electronic solutions.”
Optimised material flow
The new storage area comprises racking on five levels along 12 aisles up to 160 metres long. In total there are 11,520 storage locations and 1,100 picking locations for a maximum of one million individual items.
The pallet racking is divided into six separate sections. Each consists of an order picking aisle and two narrow aisles for replenishment, which are serviced by the three AGVs. Every afternoon, orders received by 12.00 noon are processed. The WMS (warehouse management system) determines which products are already available at a pick location and which goods still need to be replenished.
On average, the trucks rearrange around 20 per cent of the stored goods until every product can be found at an order picking storage location.
Samsonite employees use a route-optimised pick list to take the items from the order picking locations, attach a barcode label and place them on a conveyer belt in the middle of the pick aisle. From there, they are transported to a consolidation area where they are grouped by destination. A manual electric fork lift truck loads the pallets into a lorry using a dock leveller. Around 27 lorries with an average of 1,000 to 1,500 items each make their way daily to retailers throughout Europe.
Slow moving products are transported from production to the warehouse on Linde electric counterbalance trucks. Each truck places the laden 1,400 x 1,400 x 2,000 mm high special pallets into the marshalling area. After pallet profiling is completed, the load is transferred to the automated storage area of the warehouse via cantilever pick and drop stations.
AGV movement instructions are sent from the E&K system controller based on order information from the WMS. The trucks automatically pick up the pallets on their telescopic forks and transport them to the required rack location. When transferring pallets, the AGVs use an optical system to ensure positional accuracy. There is a 150 mm safety clearance between the trucks and the load in the racks.
Since there is only 75 to 100 mm of space between pallet storage locations, a pallet profiler mounted on the AGV forks confirms that the load can be stored in the rack and ensures that products housed in two adjacent rack positions do not touch each other. If the dimensions of a load exceed the standard pallet profile, the automated Linde narrow aisle truck is switched to manual operation.
When the AGVs have no outstanding orders, they travel to a designated station for automatic charging. The 80V/775Ah lead-acid battery is charged through contact pads in the floor.
Safety is paramount
Samsonite placed strict safety requirements on the system, as AGVs, manually-driven fork lift trucks and people work in the warehouse. An innovative and secure safety system prevents collisions and maximises work flow.
The picking aisle is protected with an access control system for the order picker; AGVs are not allowed to operate in this area. The neighbouring truck aisles for replenishment are located on either side of the order picking aisle. AGVs operate here, but staff can also enter. However, access management prevents the trucks operating at the same time as the pickers, who can only enter the section when the area is safe. AGVs are similarly prohibited from entering if pickers are in the aisle.
Access to the replenishment aisle is automatically blocked for manually operated trucks by a light barrier and a remote controlled emergency stop circuit on the rack entrance.
Equipment protecting the operators is fitted to the AGV, making it intrinsically safe. Should a person approach a truck, it stops in a controlled manner and remains stationary. This is essential, as the narrow aisles do not offer operators an escape route and the trucks not only travel freely in the aisles but also in an additional storage area.
After more than a year of operation, production manager Germain Ghys is very satisfied with his innovative idea.” Our operation is extremely efficient, providing a significant competitive advantage. We are constantly advancing and look forward to a successful future,” he said.
E&K Automation Ltd
Peter Holdcroft, Managing Director
Tel: 01256 880228