No part can be manufactured perfectly.  A certain amount of variation is inherent in any manufacturing process.  Tolerances are set to specify the limits which control the dimensions of important features on a part.  Individual parts are manufactured and then put together to form an assembly.  Each of these individually manufactured parts can have several different tolerances.  It is the effect of these tolerances in the assembly that makes assembly tolerance simulation studies necessary.  Hence, tolerances play a vital role in the manufacturing of any product.  

Proper specification of tolerances in the simulation model is essential.  Tolerances that are specified correctly show the exact effect they have on an assembly when simulations are carried out.  

There are two main categories of Tolerances: Tolerances and GD&T.  

Tolerance is an allowable amount of variation of a specified quantity. Tolerances are created as a function of 3DCS, allowing the user to create a link with a tolerance, the CAD and any other generated features, such as Points and Features  Any point with a Tolerance associated to it will deviate according to the Distribution and limits of the tolerance.  

GD&T is added directly to the CAD Geometry, or shown in a drawing using the CAD as a 2D sketch reference. In the integrated CAD version, a user defining GD&T in the CAD can also be leveraged to a 3DCS Tolerance Analysis model. If any points or surfaces are used, 3DCS will use and create wire-frame and points, and link them with the GD&T. When a Feature point is created on the surface with GD&T, it will deviate the point according to the Distribution and Limits of that tolerance.

Topics

GD&T

3DCS Tolerances

Process Capability Database