New system allows direct transfer of pilot production parameters to serial production; targeting 50% reduction in start-up time
Researchers at Fraunhofer IWU have developed a system for the direct transfer of parameters applied in a pilot production run of new automobiles to serial production. As a result, the serial production process could become faster and more flexible. Use of the new “try-out” system could reduce start-up times by up to 50%, sugests Marco Breitfeld, Fraunhofer Institute for Machine Tools and Forming Technology IWU in Chemnitz.
|Clamping elements attach a metal part in car body assembly. Click to enlarge.|
While more varieties of automotive models are entering the market, product lifespans are shortening, and energy costs are rising, automakers still face a protracted ramp-up time in auto body assembly. Production systems need to be adapted to each of the new parts and assemblies, which is highly time-intensive.
In order to put together individual elements, such as a door or a side panel, the manufacturers clamp the individual parts into model-specific clamping devices and weld them together. Precision is critical.
The not yet completely welded door is an unstable structure— if you adjust it at one point, then it deflects a different one. The employees have to calibrate the devices exactly, in order to set the part.—Marco Breitfeld
This process can last several months for each new vehicle model until the system is set optimally. The pilot production run does not help in this regard, because the fixtures used there have nothing in common with the ones used later.
The new device engineered at IWU allows already determined parameters to be directly transferred to serial production. The “try-out” procedure was first applied to the reshaping process at the pressing plant. Special try-out presses determine, for example, the regulating variables for quality production beyond the serial process, without interrupting the production process. The presses simulate the process parameters and the production environment of the regular system. Now, the scientists have transferred the process to car body assembly.
The clamping devices contain four functional elements that are assembled similarly to a construction kit. With height modules, the console heights can be adjusted flexibly; the angle modules determine the angle of the clamping elements. Shim modules, specific surfaces of varying thickness, are used for fine-tuning.
Workers have a maximum of ten millimeters of leeway in any direction. Through the modulus of rigidity, the researchers simulate how rigid the device would be if it were made of steel, aluminum or synthetic material.
The IWU can also unlock the potential for lighter weight using this process—not for the chassis, but for the devices and parts that the carmaker needs in order to produce. The researchers can also simulate the rigidity of the individual components and clamping elements. They test the limits of the system and determine how much weight can be saved without compromising the stability of the construction.
When a model is changed, the manufacturers often exchange entire systems. For example, this could weigh up to two-and-a-half tons for a side panel. A flexible production is impossible with such large systems.—Marco Breitfeld