QMT Features: September 2007
No screws loose
How BMW brought the quality of its 3-series up to speed through a further extension of its KISS quality management system.


With KISS Q, the core production integration control system, BMW AG started back in 1997 to implement an efficient quality management system that coordinates quality across plants and even companies. The centre of focus of the system is not just on ensuring and improving the quality of the vehicles but also on optimizing working processes and thus incurring productivity and lowering production costs. Modern information technology is the key to meeting the most stringent quality requirements – and that is why BMW AG decided in favour of CAQ=QSYS for its KISS Q project.

The automotive industry version of this standard software ensures transparency in all quality data during the production phases of body shell, surface technology, assembly, and dynamics testing, and also allows all the quality information in production to be stored, checked, analyzed, and documented in one central database.

“After the successful introduction of KISS Q in the Regensburg plant, the next job was to expand further the control, monitoring, and documentation of the processes”, says Wolfgang Schneider, the BMW project manager at IBS AG. One of these especially quality-relevant processes is the fitting of screw fastenings to individual vehicles, which goes on throughout the production process. All the vehicles that run through the assembly area have to be registered exactly and the screw fittings attached that are specific to each one. This represents one of the most critical requirements for the quality management system that is in use. The high level of individuality of the cars that are being produced requires the exact identification of every single one and the correct allocation of requirement data for the screw fastenings in order to avoid production errors. “Rework, or in extreme circumstances a product recall, involves enormous costs and can do irreparable damage to the manufacturer’s image”, says Andreas Lehner, the screw fastenings project manager. This means, for instance, that the “tightening up” of screw fastenings by hand is a very labour-intensive and time-consuming kind of inspection check and creates heavy costs as it is an additional working step. In order effectively to minimize these risks the people at BMW decided to use electronic fastening systems that bring the possibilities together into a network of spotting inadequacies immediately and of documenting, even years later  that the work has been carried out correctly. The relevant data are registered automatically in a working step and processed for the next stage in the work. The results are then available for the later user to call up at any time. “The aim of the system is to provide an efficient analysis of points of weakness all along the process chain that will enable errors to be recognized quickly and systematically and ensure that the causes are rectified immediately”, says Wolfgang Schneider, who is the head of project management at IBS AG. The main requirement of the system is to eliminate completely the possibility of a defective vehicle being delivered.
From planning to implementation

The implementation and the whole project planning was once again placed in the hands of IBS AG in Höhr-Grenzhausen (a small town northwest of Frankfurt), the firm that had already furnished proof of its know-how and its particular competence in the automotive industry during the planning and implementation of the multi-plant KISS Q system. In collaboration with BMW a concept was developed that starts by defining all screw fastenings as “Not OK” (not in compliance with specification) before any “OK” result has been obtained. This ensures that no defective vehicle leaves the works. Vehicles are identified by their chassis (or VIN) number, which is attached to the vehicles in barcode form. A wireless scanner is attached to the power screwdriver itself that registers the vehicle number and checks it against the requirement data in the system. A direct link is now made between the scanner and the start button on the power screwdriver in order to ensure that fastenings can be screwed in only if the vehicle and the requirement data have been correctly identified.

The specification data are processed in the central inspection planning system of the IBS CAQ=QSYS automotive system, KISS Q. An inspection plan is drawn up for each model series specifically and unambiguously defines the individual screwing points with the corresponding number of fastenings.

Defective screw fastenings are automatically sent to the central rework point or to wireless terminals directly on the assembly line so that they can be put right without delay and at the expenditure of very little time. The results of the relevant rework are acknowledged and added to the vehicles processing history. This process is repeated until there are no more “Not OK” readings from anywhere on the vehicle.

The architecture of the whole system

The necessary total functionality was sub-divided into four basic areas:

1.Screw fastening technology
This covers the functionality of the screwing process and the identification of the vehicle that is to be processed.

2.Control level
This handles the intermediate buffers and distributed requirement and actual data. IBS developed a control level specifically for this application that ultimately serves as a standardized front-end for the screw fastenings control systems.

As every power screwdriver takes on specific tasks and therefore also the control units possess individual characteristics, the control level has an interface function between the standardized functionalities of the superior systems KISS Q and KISS L and the specific screw fastening control units.

3.KISS Q
The KISS Q central quality system handles the inspection planning, inspection data administration, and rework management. A wireless unit has been integrated at the KISS level for mobile rework on the assembly line.

4.Wireless units
The necessary rework is indicated and afterwards acknowledged on mobile terminals, which are also fitted with a barcode scanner for identifying the person doing the rework and the vehicle. It should be noted in particular here that the transfer of the requirement data for the first screw fitting point has to be completed within ten “time units”, which measure between 60 and 80 seconds. The data themselves are transmitted in the form of “telegrams”.

Results and prospects
With the implementation of the process data securing system for screw fastenings in its Regensburg plant, BMW has laid the foundations for the further extension of its quality management system. When the system is finally completed 250screw fasting units will be connected to the control level.

The system start-up went ahead perfectly. The employees completely accept the system because it is very operator-friendly and efficient, so it greatly supports operational work. Feedback from the production departments and from management is also positive. l

www.ibs-ag.de

email: info@ibs-ag.de
  
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