A good example of how things have changed at Luton, UK over the years is the shift patterns: in 2008, the plant ran three shifts but at present runs two, from 6.00 am to 21.30 pm, five days per week. 1,500 people work at the site, 1,100 are employees and 400 are contractors and service providers.

Press line
The Luton plant is rated as the second best press shop in General Motors Europe, in lean terms. Steel coils come from Arcelor and are fully processed in house at Luton, with the exception of bodyside blanks, which are supplied as tailored pieces, sourced from Corus UK. These blanks make up around 10% of the total steel required for an X83 vehicle. Coil storage is kept lean, with enough for only three days production being kept as buffer stock.

Five presses are in operation, with two main press lines comprised of a Schuler ‘lead’ press (that replaced an older Erfurt unit, in 2000) and a smaller Komatsu tandem line that was diverted from going to GM Thailand. This press boasts a die change time of four minutes. The plant stamps the largest panels in GM Europe and produces some panels for the Astra van, made in Ellesmere Port. The Erfurt main line press has a 2,000 tonne capacity and uses manual die changing, so the change time is 20-25 minutes, using Atlas die carts to transport tooling. Routine inspections, and any ‘heavy maintenance’ are carried out by a team from Schuler UK. ‘Doppin handling’ – dedicated, fixed automated handlers, are used in the main press line, instead of robots, the tooling coming from Olofstrom, now part of ABB. The press line runs a ‘double day’ operation (two shift) on two press lines and a single shift on the blanking line, using 29 sets of dies to make 63 parts for the Vivaro/Primastar/Trafic, and four parts for the Astra van.

Suppliers to Luton

ABB robots in press line
Arcelor coil steel
Aro spot weld guns
British Federal weld controllers
Comau bodyshop robots
De-Sta-Co vacuum grippers for de-stacking
Fanuc bodyshop robots
Jervis B Webb conveyors
Komatsu smaller, tandem press
MovoMech cranes and handling equipment
Olofstrom Doppin handlers in press line
Perceptron in-line body measurement
PW weld guns
Schuler lead press
Tracoinsa bodystore rails
Voith onsite assembly services

Sharing the stress
Intelligent onsite outsourcing has helped save many jobs at Luton; where a production unit has become uneconomic, Vauxhall has contracted-out work to suppliers who are based inside the plant. One of these is Voith, who assembles the rear axle and front corner modules in a small production area located in the press shop area, from parts coming in from France, Germany, the UK and China. Testament to the tough economic times that suppliers also went through is the change of this contract; another supplier, G W King, supplied these assemblies to the Luton Plant. New equipment was installed onsite by Voith to take over this activity. ” The plant was restructuring at the same time so we took the opportunity to work with Voith and provide surplus labour into the new operation to reduce the impact of separations on the Vauxhall employees. This was a unique situation where a facility installed and managed by a contractor was ‘manned up’ by the customer. A great example of the entrepreneurial and collaborative spirit that exists within the Luton Plant. And suppliers also share some of the stress that the plant can be under due to fluctuating demand as Paul Clark tells AMS: “Voith’s new panel store for example holds all the finished Press panel stock and the contract pays out on a ‘cost per van produced’ basis. This caters for fluctuations in built vans per month, as we only pay for what we produce. However, we can also switch to a fixed ‘overall’ contract price should % volumes rise or fall vs agreed limits. This means that the company, supplier and our respective workforce’s are better protected against the inevitable peaks and troughs of production/sales demands.”

Bodyshop ingenuity
The van body starts in ‘Underbody 1’, with longitudinals – the north-south frame members that take the floors and bodysides. These are built in-house using parts from supplier TKT, onto skids with RFID tags that stay fixed to each one until they reach the paintshop. The plant keeps a four hour buffer store of all vital BIW parts which demonstrates extremely lean inventory control. The welding is a mix of automated (with Fanuc r-200 ib robots in initial spotting and Comau robots in re-spot, all using Aro guns) and some manual re-spot; operators rotate jobs every hour or every break time.

After the main underbody is assembled, the front floor is manually loaded onto a ‘magazine’ and Comau robots pick these with vacuum grippers, drop onto the underbody and then change heads to make the initial spot welds. Re-spot is carried manually out with PW guns for welding. The completed assembly is then taken by elevator down to the Underbody 2 area where it is married to the bodysides. Underbody 1 keeps a ‘bank’ of 20 units in a store on Tracoinsa rails that surround the elevator shaft. For a modern plant, there is still a lot of manual operation in the bodyshop but this will change with the X82 programme as Pat Walsh, Body Launch manager for X82 project says: “It is a win-win situation for operators. There will be increased automation in the bodyshop focusing on the more heavy welding tasks, which will allow us to position our manual stations in a more ergonomically friendly manner.

Future vision
At present the bodyshop uses a Perceptron fixed camera geometry check system but robot inspection, as is already used by Renault, is planned to give faster measurement with greater accuracy, checking many more points than at present. There are so many variations of bodyside that manual loading onto fixtures is the only practical way at present; the sides are loaded horizontally and then the ‘frame’ is powered upright and rotates to join the underbody in the framing station, dropping the sides into tabs on the floorpan. This custom-made rotating fixture is a prime example of the spirit of ingenuity at Luton and, as Pat Walsh says, “We have an enthusiastic, dedicated and experienced workforce, (the average age is 49 years).The Luton team are committed to ensure that they are all able to add value and contribute to our impressive ongoing performance. These custom stations enable that to be a reality.”

Then operators drop header rails into place to retain the sides before the whole assembly runs into a framing station for tacking and then re-spot. The roof is picked up by a manually handled vacuum gripper and placed onto the completed body. One of the last jobs in the bodyshop is fitting the two front doors and here another ingenious solution has been ‘home grown’ by the plant. A large washer, with an adhesive backing, is used between the door and the body to fix a datum point once the door fit has been adjusted. The washer remains stuck to the body and bonds onto the hinge bracket in the paintshop ovens so that after door removal and dressing, when the door is re-fitted in assembly, it is easier to fit in exactly the same register as in bodyshop.

Assembly expertise
After paintshop, the doors are removed in the usual way and a paper manifest is clipped to the end of a two-door carrier, with all the specification instructions for the colour and trim level etc. I suggested to Mike Wright that this is a slightly old-fashioned way of doing things and he explained: “We have been through some very tough times here and while I would love to have a more streamlined system with RFID tracking or similar, paper is a cheap and accurate way of doing things, it works well as our workforce takes that extra bit of responsibility to get things like door dressing right every time.”

This imaginative and resourceful attitude is shown in the kitting system used in the trim and final area. Cardboard boxes used for delivering the wiring harnesses are trimmed by hand to give easy access and then are filled by hand with a kit for underbonnet plastics and trim. These are placed in the rear of one van and are used to trim the vehicle behind. As Mike Wright says: “We have skilful operators packing these boxes for the line. Between them they worked out the kit order and they place the right parts in the right order, without even using dividers so the parts come out of the box in the correct sequence for the line operators”. The marriage station uses skillets to carry the powertrain; this is pneumatic and is recharged after each use. This could certainly be an area where a move to more automated, servopowered operation would add efficiency; marriage is fully automated at the Barcelona plant.

Cockpit assembly uses manual handlers; the IP arrives on a manual ‘AGV’ as Mike Wright says: “I have looked at a lot of AGVs and they are great but we were just not in a position to buy powered equipment during the downturn in sales and production. So we built a manually-powered trolley system that runs on a semi-circular track and is indexed on by our operators – it works perfectly and it never runs out of power or breaks down!”

Luton today – economic and effective

Renault has ABB and Fanuc robots at Sandouville whilst Luton’s bodyshop uses Comau and Fanuc machines. On three shifts the plant built 95,030 vans in 2007 – a record year. It is the UK’s biggest light commercial vehicle builder, making vans for Vauxhall, Opel, Renault and Nissan. One major benchmark is the time required to build a van – hours/van or HPV – and gross conversion rate (GCR). HPV and GCR are very important and Mike Wright is justly proud of the figures: “Our HPV was 47.1 in 2002. We have improved this to 24.7 in 2012, and will further improve with the new model by 2014.

“There is no Vauxhall/Opel plant building fewer vehicles. It is a low-investment, low-cost plant. We do not have the same automation as other plants. We must be more efficient with our people.” And the workforce is one of the keys to Luton’s survival and success as a plant, as Wright says: “The average age of the operators is 49 years, dedicated, faithful guys and girls. For example, our level of attendance is an industry benchmark. It is a good workforce, and one that is significantly smaller than it was. The plant is driven by performance metrics addressing, for instance, safety, people engagement, quality, cost and efficiency.” Although an old plant with a layout that sets some challenges, Luton is still efficient, having one of the lowest cost bases in Europe. And there are plans to boost integration on the site to increase the supplier footprint, even to create a supplier park. “Last year we brought in the outside supplier of longitudinals and cross-members,” says Wright. “It installed the whole of its assembly lines on our premises. Production of struts and corner assemblies has also been brought in. We are working with purchasing and global supply chain to increase the local supplier footprint for Vivaro and if more vendors come on site, fantastic. We are looking to maximise manufacturing and supply work in the UK.” The Luton plant will continue on two shifts to build more than 70,000 vans a year based on an uptime of 95% in assembly.

All new for X82
Of course the big news at Luton is the forthcoming new generation van – codenamed X82 (current model is X83). This is a co-development of GM and Renault; Vauxhall/ Opel has complete responsibility for manufacturing strategy, whilst Renault lead the product development. The plant is to replace many of its robots under a £95 million investment to ready it for building the next generation Vivaro van from 2014. The first van is due to roll off the production line in May 2014, with the last X83 vehicle just a week earlier. More than half of total investment will be spent in the bodyshop. The spending will include new assembly fixtures for underbody, bodyside and closure lines, as well as body framing. Press lines will receive new dies supplied out of China, Korea and Germany for a value of around £30m as part of additional vendor tooling costs. Today, the plant has 89 robots in the bodyshop and 50 in the paintshop. At present, it is planned to carry over around 25 percent of robots; the aim is to achieve high percentage re-use without compromising efficiency.

From 2014 until 2025 the plant will produce only Vauxhall and Opel vans, to a capacity of around 60,000 per year over the planned life cycle. However, the Luton Plant has additional spare capacity, which if realized would enable them to produce in excess of 100,000 units per year. Renault will build its own version of X82 (the Trafic) at the larger Sandouville Plant, near Le Havre, where planned capacity is expected to reach 80,000 a year, as a start point. Sandouville currently produces the Laguna and Espace passenger car ranges. Their future van production content will also include a high roof version of the X82 that will be produced for Renault, Vauxhall and Opel customers.

As Wright says much will change but much will remain the same: “The new model will need roughly the same footprint, though for a time we will have a common final line (for the X83 and X82) in the bodyshop, where we will change over the unique tooling in between trial builds of batches,” he says, adding that the final layout has not yet been decided. “We want to minimise investment, therefore we must reuse as much equipment as possible. We also want to improve efficiency. We have learnt many lessons since the bodyshop was conceived 13 years ago, including access floors and the delivery of parts to the bodyshop but it is the present bottleneck. We will also require a new turnaround area,” says Wright. “This is a temporary on-site space for the storage of components whilst we build new cells or lines in some areas. Once we switch over from X83 to X82, old cells will be dismantled and these areas used for storage.”

Added to the optimism that shows in the management and workforce at this remarkable plant, in September 2011 the company started employing apprentices again, for the first time in over 30 years.