sequences 255,000 unique mini dashboards for Intier
Magna is one of the most diversified automotive suppliers in the world – designing, developing and manufacturing automotive systems, assemblies, modules and components, and engineering and assembling complete vehicles. With production, engineering and R&D centres in 23 countries on 5 continents, Magna supply content to virtually every automotive manufacturer for every major brand in the automotive world.
Magna's Intier Automotive Interior's facility in Redditch in the UK assembles 255,000 unique cockpits a year for the hugely popular MINI and delivers them to the BMW manufacturing plant in Oxford. The MINI, which is claimed to be the world's most unique car, is made to order and can be specified with a huge combination of options (theoretically 150,000,000,000,000,000 or 150,000 billion), so in any year it is unlikely that two identical MINIs leave the Oxford plant.
Which explains why, when Intier needed a new automated storage area to provide a buffer stock between its Redditch plant and the MINI plant, it installed an integrated conveyor and order picking system designed and manufactured by Excel Automation, the UK's leading supplier of automated materials handling systems.
Commenting on the new system, Intier production manager Bob Clifford says: “Our contract with BMW is for Just in Time deliveries of MINI cockpits (fully assembled dashboards), so we need to ensure that every one of the 255,000 unique cockpits leaving Redditch every year is united line-side with its unique MINI, forty miles away on the assembly line in Oxford.
“We also wanted to maintain a buffer stock in Redditch so the decision was taken to create an automated storage area adjacent to the main cockpit assembly line.
There were severe constraints on the space available in the plant, which was further restricted by the location of a roof support column. The number of cockpits we were able to hold in the storage area would therefore depend on the resourcefulness of the design put forward by the materials handling manufacturer.”
The decision to award the contract to Excel Automation was taken by a team at Intier. Considerations included an innovative approach to the space restrictions, the performance and reliability of the conveying and handling system Excel had already designed and installed for the cockpit assembly line, and the ease of integration Excel was able to demonstrate.
The solution devised for the storage facility is fully integrated with the assembly line and consists of two Excel designed and built automated stacker cranes designed to pick-up and place to either side of two beamless drive-in racking aisles. In the limited space available it is able to store 140 cockpits.
At the same time that the storage area was being installed, Excel converted the existing assembly lines from an indexing system to a continuous operation in order 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 directly 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 are capable of delivering 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 in order to maintain the build sequence dictated by the Oxford plant. Lorries carry 30 cockpits per trip with numbers 1-15 loaded on the lower level and 16-30 on top. The crane is programmed to retrieve in a pre-determined sequence – 1 and 16, 2 and 17, 3 and 18 and so on. The change-round time allowed for emptying and filling the eleven lorries that deliver continuous batches of cockpits to Oxford, is just five minutes, so the lorries themselves are also fitted with an Excel conveyor system, which increases the efficiency of the feed by enabling the 30 cockpits to be loaded straight onto the lorry in a single operation.
The fully automated hi-speed cranes operate on a dual redundancy arrangement allowing one to continue working while the other is 'parked' for maintenance. They were built by Excel in its Worcester factory and can accelerate at one metre per second and deposit a cockpit, empty and pick up again, in just one minute. Whilst they are based on a standard industry format, notable features for the Intier application include two sets of forks and special-purpose drives and controls to provide the speed and accuracy to order-pick for this very demanding operation.
The cranes also use a laser guidance system that positions them to within 2mm, the extreme accuracy being necessary due to the space limitations in the area. An on-board PLC allows manual, semi-automatic and fully automatic control of the cranes and in the event of a complete failure of the off-board control system, an operator can continue the process by extracting order numbers from MAGIC and entering them manually into the on-board PLC. Before being installed Excel completed a full simulation to provide a virtual demonstration of the systems operating capacity.
The racking is also purpose-built to a beamless drive-in design, which enables it to fit within the limited height in the storage area, and enables the cranes to operate effectively in the limited space.
Commenting on the performance of the new storage facility, Bob Clifford says: “Increases in efficiency and productivity come from the combination of automated storage and intelligent crane management. Where previously cockpits had to be stored in order, they can now be stored randomly and the crane sorts it out. This has proved to be a major benefit when re-working is required.
Previously, to ensure that cockpits entered the storage area in the right order, the assembly line had to be stopped while a cockpit was taken off-line and re-worked. Now the re-worked cockpit can be introduced later and the crane will find it and place it in the correct sequence.”
He adds that before the Excel system was commissioned, cockpits would sometimes leave the line out of sequence due to re-working, etc., which meant Intier was liable for penalty payments.
“Now the Excel handling and storage system is achieving exactly what we wanted, and we don't have that problem.” He says: “It's a very good system and it keeps working shift after shift.” (Request figures on increases in productivity from Bob)