Case Study
In order to ensure the manufacturability of assemblies to the Body-in-White structure in car series production, optiSLang supports engineers at Mercedes-Benz AG in the planning and developing of adequate tolerance concepts.
Introduction
Today’s mass production environment requires assemblies to be built up with a specific dimensional accuracy, ensuring the fulfillment of functional requirements and their processability to a higher-level of assembly. The manufacturing of single parts always produces some deviations. The assembling process itself also causes inconsistency, for example, due to inaccuracies in the positioning of the parts at the manufacturing plant or in the joining process as well as due to elastic deformation.
Tolerance analysis generally provides ranges, in which single parts are allowed to deviate, thus, the functionality of the assembly is still guaranteed. It needs certain information to build up such a tolerance analysis model properly. A distinction can be drawn here between product data, such as part geometry and tolerance information, as well as process data, for instance the assembly graph, jig and fixture concept, joining locations or measurement points. This information is necessary to define contact conditions, ranges and measurements with the help of tolerance simulation software. In the automotive industry, the build-up process of these tolerance simulation models is time consuming and, due to human interaction, fault-prone. Today, more than one hundred assemblies are attached to a sophisticated Body-in-White (BiW) structure, which itself already consists of several hundred parts. In order to ensure a manufacturability of the assemblies to the BiW structure in series production, experienced engineers are required for planning and developing adequate tolerance concepts. Regarding the multidimensional orientation of the tolerance chains in a BiW structure, it is a challenge to find an optimal concept for attaching certain parts. Beside long-term experience, the usage of IT-tools is indispensable for helping the engineer in making the right decision. This article will explain an approach how to interlink optimization software, product and production development data as well as CAT-simulation tools in order to conduct a sensitivity analysis on simulation input parameters. Furthermore, it will be shown how this approach can be integrated in the process of the automotive BiW sector. The concept was firstly implemented by using the software optiSLang for the sensitivity analysis and 3DCS for the tolerance analysis.