If any can be found, then determine where the issue would first be identified. Identify the tolerance requirement limits where manufacturing or performance of the final system are adversely impacted. A lower-cost component may come with the unwanted side-effect of wider tolerances and less manufacturing control. Mathematically test these against the requirements of the design to see if there will be violations within the system.Ĭonsider the impact of the total variance against the cost and performance during the design stage.

Determine the expected tolerance variance from suppliers and vendors during the design stage. The expected attribute variance over the manufacturing life must also be part of the decision process for their design-in use. Components and part selection should not be chosen based only on functional use, cost, and performance within the design. ** GD&T Tutorial on Projected Tolerance:**This geometric dimensioning and tolerancing or GD&T tutorial will discuss projected tolerance and its application and benefits for preparing engineering drawings.During the product design stage, a tolerance stack-up review should be part of any robust development. The root sum square or RSS or statistical tolerance stack up method is useful for doing the assembly tolerance chain stack up analysis of an assembly with large numbers of components in it. So, The thickness dimension ( X) with the tolerance zone of the assembly will be:.Find out the tolerance zone of the assembly like below:.Find out the standard deviation of the tolerance zone of the assembly like below:.Find the Standard Deviation (σ) of Each components tolerance as below:.Calculate the nominal thickness of the whole assembly as below:.We have the thickness and the tolerance values of all the plates (plate-1, 2, 3 and 4). The aim of the assembly tolerance stack up analysis is to find out the overall thickness of the assembly ( X) with tolerance. Let’s take the following assembly as an example: How do you really perform a RSS tolerance chain stack up? How to Perform Root Sum Square Assembly Tolerance Stack Up? It assumes that most of the components fall to the mid of the tolerance zone rather than at the extreme ends. The root sum square (RSS) method works on a statistical approach. What is the RSS Method of Assembly Tolerance Chain Stack Up? That’s why you will get a wider tolerance zone for the assembly in the worst case method. Also, the worst case method assumes that all the components will fall in the extreme ends of the tolerance zone. Though the worst case method is very simple to perform, it is only suitable when small numbers of components are in the assembly.

I already have an article on worst case method assembly tolerance stack up analysis.

There are many methods and tools available for performing assembly tolerance stack up analysis.

Tolerance stack up