Object types
A tolerance analysis measurement contains the following object types.
• Measurement—A linear measurement between the selected features.
• Part—A part from the Creo Parametric model that is involved in the measurement variation. It may be a real part from the Creo Parametric model or a virtual component representing the top-level assembly or one of the subassemblies.
• Dimension
—A linear location or size dimension from the Creo Parametric model. For standard linear and size dimensions, the variation of the measurement is based on the tolerance properties of the dimension in Creo Parametric. For basic linear dimensions, the variation of the dimension is based on the related GD&T selected from PTC Creo Parametric.
• Interface—In between each pair of parts in the Measurement Table, you will see an interface object that represents the assembly interface between the adjacent parts. The properties of the interface object depend on the last feature of the preceding part and the first feature of the next part. For example, when the preceding last feature is a pin and the next first feature is a hole, the interface object represents the pin/hole assembly interface. The drop-down menu in the attachment column allows you to specify the attachment option for the interface. For pin/hole interfaces, you specify whether the pin is centered in the hole, tangent to the right or left (based on the orientation shown in the dimension loop diagram), or floating.
When you select the floating option, an additional variable is introduced into the model that represents the random variation of the pin in the hole. The distribution of the float variable is calculated based on the distributions of the pin and hole diameters, assuming a uniform distribution of the clearance.
If there is a gap between two adjacent parts, it can be filled in the analysis using a Close Gap interface. A Close Gap element between two parts removes the clearance between them in the analysis.