Product category:
Automation and assembly equipment
News Release from: Mike Page - editor's feature articles | Subject: Body-in-white fabrication, assembly, welding
Edited by the Manufacturingtalk Editorial
Team on 21 May 2007
Automation determines BIW consistency
Where prudent, a German builder of luxury car body-in-white assemblies on a low volume basis uses automation where consistency of assembly is required, reports the editor, Mike Page.
Volkswagen (VW), headquartered in Wolfsburg, Germany, is building its body-in-white (BIW) assemblies for three models of luxury car at its subsidiary, Volkswagen Sachsen (Saxony) Mosel plant, near to Leipzig The body models are for the 'Passat Limousine' and the 'Phaeton', 'Phaeton Long' version and 'Phaeton' armoured version
This article was originally published on Manufacturingtalk on 29 Oct 2001 at 8.00am (UK)
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The plant also produces bodies for the 'Bentley Continental GT' and 'Continental Flying Spur'.
The press shop on the site, which includes German Schuler panel transfer presses, produces aluminium panels and components including doors and roofs.
Other pressings - steels/high-strength steels and aluminium - are sourced from VW's other plants.
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Engines and transmissions for the body assemblies come from various VW and suppliers' plants, including VW Sachsen's plant at Chemnitz, which produces four-cylinder petrol and diesel motors for high volume models.
The only volume cars produced on the site at VW Sachsen are the Golf and Passat.
A recent visit made to the 1,800,000m2 Mosel plant saw the BIW assembly for the Phaeton and Bentley models in the 12,000m2 Hall 21 and flexible assembly and marriage with the engine/transmission platform assembly for the larger volume produced Passat B6 in the much larger Hall 5.
* Welded assembly - the Phaeton and Bentley BIW assembly lines use mostly manually operated electrical resistance spot welding guns and operator-fed, Fase electrical resistance projection welders with some robotic assistance provided by FANUC Robotics' and KUKA robots.
Side panels, floor pan and roof are assembled at an automatic mechanical clinching station, before finishing with manual spot welding and some riveting and Nd:YAG laser welding.
One of the three managing directors of the Mosel plant, Dr Frank Loeschmann, said that while the overall emphasis was on productivity, the use of expensive, automatic laser welding is justified on the grounds of consistency and stability.
Altogether some 2.8m of Nd:YAG laser welded overlap seams are used in the Bentley and Phaeton cars.
Note also that the Phaeton and Bentley BIW assemblies have up to 40m (Phaeton) and 120m (Bentley) of adhesive bonding/sealant seams.
Robotic MIG welding and MIG brazing processes (that is a low temperature MIG process using brazing wire filler) - with welding systems provided by Fronius, Austria - are used to provide short weld seams, such as welding a fender to the body side.
Note the robotic welding is also used on safety critical joints.
In building the Phaeton and Bentley BIWs, Hall 21 plant engineer Stefan Possner said that 'team principles' with multi-tasking assembly operators are used.
There are 28 workstations on BIW and line cycle time is 16 min.
To build five different models with a possibility of 64 different versions there are only seven/eight different types of stations.
In total, some 25% of assembly work is manual, assisted by 38 robots supplied by FANUC Robotics and KUKA.
The Hall 21 is working on a three-shift basis and in February 2007, on 50-60% of full capacity.
Handling of BIW assemblies is by 'sea hook' overhead conveyor system - mostly by Demag - with emphasis on avoiding physically fatiguing or stressing the assembly operators.
On completion, the BIW assemblies are checked in a large Brown and Sharp DEA Bravo NT inspection station with two travelling column co-ordinate inspection machines (CMM).
Current output from Hall 21 is around 150 units/day.
The Phaeton and Bentley BIW bodies are then shipped to the Dresden, Germany and Crewe, England, plants for final assembly, finishing and fitting-out.
* Building the Passat B6 and Golf cars - there are two assembly halls - Halls 5 and 6 - laid out in parallel currently producing some 1150 units/day.
Hall 5 has four parallel, flexible assembly lines with - in total - more than 400 operation stations and 430 operators producing assembled cars on an average 2 min cycle time.
The larger Hall 6 is dedicated to the production 'Golf 5' car, but one of the lines can produce Golfs or the larger Passats.
Typically, Halls 5 and 6 can produce 1000 Golfs and 150 Passats/day or, for example, 600 Golfs and 550 Passats - depending on market demand.
A visit was only made to Hall 5, where the most interesting assembly operation was the automation-assisted 'marriage' of the pre-painted BIW body to the engine/transmission/suspensions platform.
The timing of an overhead conveyor with 'scissor-lift' body handling system (supplied by Welcal Maschinenbau and FATA Automation companies) with a computer-managed automatically guided vehicle (AGV) system carrying the platform, achieves the initial 'marriage'.
The platform has special, unpowered nut-running units equipped with nuts, which position themselves, with the bolts on the body underside.
Once 'mated', the body/platform assembly arrives at a nut-running station.
On each side of the AGV, two automatic units (locally called 'screwing islands'), each fitted with four programmable nut-runner drive spindles on individual X-Y carriages, sequentially locate to the AGV's nut-running devices.
They automatically carry out a nut-running sequence - typically around 18 bolts on the right-hand side (I did not see the left) - to assemble the body to the platform and the front and rear suspension + axle units.
While the automatic nut-running operations are working, two, at car body level, operators' platforms, either side of the AGV track and equipped with automatic and manual nut-running systems, approach the engine compartment.
There is one operator on each platform, and each operator secures various attachments of the engine/transmission assembly to the body.
Also on the line are KUKA robotic units equipped with Perceptron machine vision/monitoring units and a Kleinmichel automatic adhesive application system.
These units automatically assemble front and rear glazing units to the body.
* Suppliers located nearby - in the immediate area outside of the plant are various suppliers' warehouses/factories, which deliver components, sub-assemblies, front and rear fender/lighting modules - and so on - on a 'just in time' basis to the main Mosel plant.
For example there are 15 different modules - such as a complete cockpit module - for the Passat assembled near the site by partnered suppliers, such as Gillet or Brose.
Other suppliers of systems, sub-assemblies and components include Visteon, Grammar, HQM, VW Braunschweig and VW Wolfsburg, GKN Transmissions (which occupies a nearby plant formerly owned by Citroen), Johnson Controls, Rehau, Eurofit (wheels), SAS Autosystemtechnik and Plastic Omnium.
* About the Mosel plant - following the reunification of East and West Germany in 1989, VW began assembling its 'Polo' cars in Saxony.
VW Sachsen was founded in December 1990 as well as a VW technical training institute in Zwickau.
Then production of the 'Golf II' began in 1991 while VW acquired an engine assembly plant in Chemnitz.
By 1995, the Passat models were being produced.
Production of BIW bodies for Bentley and Phaeton began in 1997/98.
This part of germany has long been a traditional car manufacturing area - notably the 'Trabant' series, when part of former East Germany.
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