Here’s how BMW in Munich was able to increase process reliability for front and rear end assembly. Article by Carl Zeiss.
The front-end decisively characterises the silhouette of a vehicle. For this reason, perfect assembly and strict adherence to the joint plan are of great importance to car maker BMW. For a long time, gaps have been tested only with gap gauges. In this process, deviations of tolerances are effectively visualised, however, it does not contribute to determining the cause of an error. In the past, in order to track down this error, vehicles with a conspicuous joint and gap profile, therefore, had to be driven to the measuring room and measured there.
So, the department searched for a digitising system to optimise the assembly process. It should be used right after the final assembly and should provide as precise results as did the system in the measurement room.
Intuitive 3D Scanning
The hand-held ZEISS T-SCAN laser scanner enables fast, intuitive, and highly precise 3D scanning. Hand scanner, tracking camera and the touch probe are perfectly matched. The modular system can thus be used for numerous applications. Here, the unique scanning speed and the precise measurement results are of great value. This is because the surface of the component is scanned contact-free and lightning-fast with the help of the laser line generated in the hand scanner. Around 210,000 points per second are recorded—more than with any other conventional method. As the tracking camera detects the position of the scanner, 3D surface data can be calculated with the help of triangulation.
With the touch probe, it is also possible to take tactile measurements of additional single points, for example, in order to capture hole edges or not observable depressions. The data captured with the ZEISS T-SCAN thus describes the actual state precisely. This can then be easily compared with the target specifications, as defined in the CAD model. Deviations can be quickly detected in a user-friendly way with a false colour comparison of the entire surface.
As the ZEISS T-SCAN also fulfils the highest ergonomic demands, fatigue-free scanning even of larger components is possible. Thanks to the light and compact scanner housing, the ZEISS system can also easily capture data in areas that are difficult to access. The intuitive and easy handling extend the range of applications or user groups.
Since March 2016, three assembly workers have been inspecting front and rear ends of an average of six completely finished vehicles per day. As a result, joint and gap widths of the two-part and rounded off radiator grille, the so-called BMW kidney, the headlight, and the bumper are measured. The briefly trained operators of the ZEISS T-SCAN capture 80 to 90 measurement points at the front end and 40 measurement points at the rear end of the various models. The measured actual values are then compared with the set values of the CAD model. Within two hours, it can be determined whether the front and rear ends show any defects. In this way, the quality engineers of assembly and body construction can counteract much faster.
For the quality and process engineers, the ZEISS system is therefore an important prerequisite to more effectively control in-house processes as well as those of the suppliers. Thanks to the portability of the ZEISS T-SCAN system, the apparatus for the assembly of the front and rear end can be measured directly in the production hall.
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