The work is carried out as part of the CLIC/Quick GPS/TZT project. In the ISO dimensioning context, the objective is to define the functional dimensioning of a mechanism in order to satisfy some functional requirements and then, for each part, to define the manufacturing and control dimensioning for a given manufacturing procedure.
Our approach consists in collecting the know-how of the designers in order to translate their wishes into geometric functional requirements and functional specifications of the parts, including an optimization of the average dimensions to maximize tolerances with an isocapability distribution, with or without statistic calculations. The effect of thermal expansion has been included in the calculations.
The "analysis straight lines" method enables the 3D calculation of the tolerance stack-up resultant (including the radial dimension), compatible with a probabilistic method, by expressing the resultant as a function of the tolerances and nominal dimensions. Based on this relation, tolerance synthesis has become possible. Over time, this work was extended to hyperstatic constraints.
In addition, the Quick GPS software system was designed to allow single-part ISO functional dimensioning (without tolerance stack-up) using a generation principle based on links between junctions.
After Quick GPS became mature, the System@tic/Astec QUICK project was started in order to have the software assessed and tested by industry.