Building a car engine is a highly complex task that requires multiple studies. Studies are required to understand the behavior of the materials under heavy heat and pressure conditions. Studies are required to understand the movement of the fluids through the engine for optimization. And of course, studies are required to understand how much variation to allow during the manufacturing process.
The automotive industry is one of the leading industries in the use of tolerance analysis during the design phase. Automotive companies understand that tolerance stack-ups are required early in the design process to properly manage variations that will be occurring during manufacturing. But they also understand that manual or even Excel-based stack-ups are not sufficient for the demands of their design teams.
Geometric Dimensioning and Tolerancing or GD&T has been in use for many years and is playing an increasing role in the automotive industry. Whether based on the USA’s ASME standard or the international ISO standard, automotive companies are using GD&T to help properly communicate the intent of the design to the manufacturing facilities.
Many companies have final vehicle assembly plants located in countries and regions throughout the world. The costs of shipping out-of-compliance parts to an assembly plant on the other side of the world can be very high. To solve this problem, automotive manufacturers are using automated software to pull information directly from the CAD systems. Such software reads the GD&T from the CAD models, such as CETOL, CATIA, and Pro/e, and increases the efficiency and effectiveness of the design engineer.
GD&T and CETOL-type tolerance studies are performed in all areas of automotive manufacturing. Body in White and sub-assemblies also benefit from better communication and more detailed information available through the use of both GD&T and tolerance analysis. The connectors of the electrical system are very sensitive to manufacturing variations and benefit from these types of studies.
Randomization-based studies, such as those used in a Monte Carlo-based analysis, lack the precision necessary to correctly predict the behavior of an overall assembly. For tolerance analysis to be accurate, it needs to be performed as a statistical tolerance analysis.
In summary, to properly predict the variations that will occur when building complex systems in the automotive industry, proper use of Geometric Dimensioning and Tolerancing is necessary. The use of GD&T and tolerance analysis can decrease the costs and time to market in the highly competitive global automotive market.