High-tech handling in top gear: automated storage system ensures that Mini cockpit assemblies reach BMW just in time.
INTIER Automotive Interiors at Redditch has installed an automated handling system to deal with the 255,000 cockpit assemblies--fully assembled dashboards-that it makes each year for the Mini.
The essence of the Mini production line at Cowley is that each car is built to order on a just-in-time basis, and that means a huge number of options on major components such as the cockpit and a demand for precise sequencing of orders as they are got ready and then delivered from Intier to BMW.
Intier's production manager Bob Clifford said: "We need to ensure that every one of the 255,000 unique cockpits leaving Redditch each year is united line-side with its unique Mini 40 miles away on the assembly line."
To give itself some respite with a small buffer stock, Intier, which is owned by Magna, has installed an automated storage area next to the main cockpit assembly line. The area isn't large, and one reason why Excel Automation won the contract was its innovative approach to space restrictions.
The storage facility is fully integrated with the assembly line and consists of two automated stacker cranes designed by Excel to pick up and place to either side of two beamless drive-in racking aisles. In the limited space, the system can store 140 cockpits.
At the same time the storage area was installed, Excel converted the assembly line from an indexing system to a continuous operation to integrate the two facilities.
The build process at Intier starts each Monday when an electronic file is sent from BMW in Oxford detailing the build schedule for cockpits required the following week.
From this point the whole operation, including assembly line, conveyors, cranes and despatch, is run by an Intier-designed build system called Magic that instructs the assembly line via a Siemens PLC to begin production of the cockpits.
Once a cockpit is completed and transferred from the assembly trolley to the shipping platen, the PLC writes a tag detailing which cockpit is on the platen, its order number and sequence number. The information is then sent to an off-board Siemens PLC in the storage facility, telling the crane to expect a delivery, which cockpit is in transit and where to store it in the racking.
When the lorry is due to collect the next shipment, the crane already knows the picking order needed to ensure that it is loaded in sequence to arrive line-side in Oxford to meet its designated Mini.
The assembly and storage systems can deliver 60 cockpits an hour, with the Excel cranes automatically sequencing them to ensure that the right cockpits are put into the two-tier accumulating conveyor system or "transport cassette" and delivered to despatch for loading in the correct order. Each cassette is effectively a "false lorry" with 15 cockpits loaded on the upper level and 15 on the lower level.
Any faulty cockpits coming into the store are placed in a special area to await rectification, which has to be completed within the cycle of 140 units to maintain the build sequence dictated by Oxford. Lorries carry 30 cockpits per trip and the crane is programmed to retrieve in a predetermined sequence.
The change-around time for emptying and filling the 11 lorries that deliver continuous batches of cockpits to Oxford is just five minutes, so the lorries are also fitted with an Excel conveyor system, which enables the 30 cockpits to be loaded in a single operation.
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|Title Annotation:||AUTOMATION FOCUS|
|Publication:||Professional Engineering Magazine|
|Date:||Jan 28, 2009|
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