ELLESMERE PORT, UK - General Motors has overhauled its Vauxhall assembly plant here for the new Astra.
GM's £300 million ($489 million) investment has focused on automating the body shop and creating a Japanese-style organization in trim and final assembly. A supplier park, with three companies, has also been created adjacent to the plant.
The new Astra, which was launched in April, is also built at Bochum and Eisenach, Germany, and Antwerp, Belgium. All plants use identical processes, though vol-umes vary.
The spending at Ellesmere Port is an investment for the future, said Vauxhall Chief Executive Nick Reilly. 'Strictly speaking, we only needed to invest £120 million to £130 million to start production of the new vehicle,' said Reilly. 'The rest was discretionary. By going for a higher investment, we have given the plant the opportunity to stay in the forefront.'
New flexibility A high degree of flexibility built into the new welding and assembly facilities will smooth the way for future models, according to Reilly.
With the new, flexible body shop, a new model could be introduced for £20 million to £30 million less than the sum required if the body shop was not flexible, he said.
Also, the general assembly area has been reorganized to raise quality and productivity levels. 'We are not the best yet, but we will be with-in the next two or three years,' he said.
Roughly two-thirds of the £300 million investment was focused on processes carried out. The plant now has a capacity to make 45 cars per hour - about 30 percent higher than the previous Astra model, which was 35 cars an hour.
GM has installed 500 robots from Fanuc of Japan in the body shop and a framing station from ABB Preciflex. The framing station brings together the front, rear, sides and base of the vehicle and welds them together.
It is designed to be highly flexible, using three sets of tooling: one for the front half of the body, one for the rear and one for the base. Each set can be automatically changed over for different models. In total, the machine can accept four sets each of front and rear tooling and two sets of 'base' tooling. For the three-and five-door and wagon models currently in production, an additional tooling set is only needed for the rear section.
All except two of the welding operations are automated. 'The main advantage of using robots is the quality. You know exactly where the spot is with a robot, which is not the case for hand-applied welds,' said Adrian Tatton, manager, manufacturing engineering.
The body shop employs 170 people on each shift, about the same as for the previous Astra. But the body shop now handles all sub-assembly welding.
That used to be located at a sepa-rate facility on the Ellesmere Port site, and employed 200 people who have now been deployed elsewhere in the plant.
Reilly said that the trim shop has been reorganized, though use of automation is limited. The line is split into four parallel sections, between each of which is an over-head buffer of 12 cars. This gives better access for the supply of com-ponents than the U-shaped convey-or across a problem, he can stop the line by pulling on a chord without completely disrupting production.
The defect is then dealt with before the vehicle leaves the station and, where possible, before the buffer ahead of the defect becomes empty.
Full Andon will be introduced over the next two years. It will involve the purchase of about 150 hand tools which will be connected to the conveyor control system. Any bolt tightening which is outside the tolerance of a tool will automatically stop the line. Maintenance personnel will be alerted to the fault by a pager capable of displaying the exact location and nature of the stoppage.
Manual, robots don't mix Only one general assembly operation is robotized, the placing of the spare wheel in the trunk.
Tatton said it is complicated to mix manual and automatic work.
'Automation breaks down,' he said. 'You can expect an automated machine to be operational 95 percent of the available time, whereas manual operations to keep the assembly line running smoothly.'
Increased reliance on modular vehicle design has reduced the work content of the trim line.
'We have designed the new Astra to be constructed from modules, as far as possible,' said Tatton. 'This makes it easier to build and guaran-tees quality.'
For example, the B-pillar trim module, including seat belt mecha-nisms, is assembled off-line and then installed in the car in a single procedure. The hydroformed front subframe is delivered with control arms, steering arms and stabilizers already attached.
At any one time, only three to four hours' worth of parts or subassemblies is held line-side. Of the 25 per-cent of material that is externally supplied as preassembled modules, the majority is delivered direct from the supplier park adjacent to the plant.
Supplier park The three companies in the sup-plier park are GM-owned Delphi area. A further 162,000 square meters is available for develop-ment, but GM has no specific plans to install other suppliers there.
Delphi, which supplies 33 different product groups, has two main functions. First, it arranges the supply of components from 73 different manufacturing locations in Europe and delivers them to the Astra assembly line in the correct sequence.
Second, it builds three major sub-assemblies: the rear axle assembly, the front cradle, and the front strut assembly.
The front cradle incorporates the electrohydraulic power steering system which the new Astra is the first GM Europe vehicle to use.
Supply of the steering unit is currently split 50-50 between Delphi and TRW, though TRW will be phased out in the near future, a Delphi source claims.
All parts from the Delphi facility are delivered in sequence. They are loaded onto specially designed dol-lies, which carry one type of part and are designed to occupy as little space at the assembly line as possible.
GM gives provisional notification of its requirements 10 days in advance, and a final schedule three days before the components are needed on the line. As each vehicle leaves the paint shop, Delphi receives confirmation of its exact specifications, leaving two to four hours for delivery of the components.
Mackie supplies parts such as the cooling module, while Plastic Omnium delivers the bumper assembly complete with attach-ments such as built-in fog and spot lamps.
GM still assembles its own seats, and will continue to do so, at least for the life of the new Astra, said Tatton. Seat frames are bought from Johnson Controls in Telford, UK, and all other assembly is done at GM.