Expanding Tolerance Analysis for a Robust Product Design Expanding Tolerance Analysis for a Robust Product | Page 4

4 Expanding Tolerance Analysis for a Robust Product Design Fig. 4. Critical Surfaces of a locking mechanism Fig. 2. Conceptual Design of an oven Eventually, the concept design needs to be created in a CAD system. During this stage, a review of basic tolerance assumptions can occur. Surfaces such as the pin’s outer surface that touches a hole, or the inner surface of a whole that surrounds a pin are highlighted. After the critical functions are identified, equations can be used to translate the model into a mathematical representation of the surfaces. For a pin in a hole, the equations would be: 3.3. Identify Critical Functional Features The progression from a conceptual design to detailed design begins with the identification of the critical function features. Many features are cosmetic in nature, such as the roundness of a door handle. But the critical functional features would include the hole where a spring attaches, or the gear surfaces that interact with each other. In this example, a simple locking mechanism is shown in the whole parts: The translation into mathematical representation leaves a visual of the model that looks more like this: Fig. 3. Solid model of a locking mechanism As the critical functional features are identified, the representation of the assembly looks more like this: | www.sigmetrix.com