ASQ CQT sample bank question
Question regarding sample bank question:
 
An assembly of three parts has an overall tolerance of plus/minus 25mm. Two of the parts have tolerances of 10mm and 15mmm each. What is the tolerance of the third component?

What is the formula or computation for this question and where can it be found in the Certified Quality Technician Handbook?                        
4 Replies
Maybe I am missing something obvious but using worst case method the two parts with the given tolerances of 10 and 15 have already consumed the tolerance band of the assembly at worst case meaning the 3rd component would have to be +/- 0 mm.  anything larger and the 3rd component would push the assembly over or under tolerance.  That said there are also 3 sigma methods for calculating stackup which could allow a small tolerance on the 3rd component.  I'm interested to see other replies
Hi Mark, oddly enough the answer is 17 mm. The method for solving is the squares root of the sum of the squares however, I get 18 when I perform this operation. I'm hoping I can get this figured out before I attempt the test.

@Gregory Mayrand:
Question regarding sample bank question:

An assembly of three parts has an overall tolerance of plus/minus 25mm. Two of the parts have tolerances of 10mm and 15mmm each. What is the tolerance of the third component?

What is the formula or computation for this question and where can it be found in the Certified Quality Technician Handbook? bitlife

This type of problem falls under the topic of "Statistical Process Control" in the Certified Quality Technician Handbook, and specifically under the section of "Process Capability and Performance". The formula for this problem can be found in various sections of the handbook, including the section on "Tolerance Analysis" and the section on "Calculating Process Capability Indices".

@Gregory Mayrand:
Question regarding sample bank question:

An assembly of three parts has an overall tolerance of plus/minus 25mm. Two of the parts have tolerances of 10mm and 15mmm each. What is the tolerance of the third component?

What is the formula or computation for this question and where can it be found in the Certified Quality Technician Handbook? melon playground

Tolerance of assembly = sqrt(10^2 + 15^2 + Tolerance of part 3^2)
25 = sqrt(10^2 + 15^2 + Tolerance of part 3^2)
625 = 100 + 225 + Tolerance of part 3^2
Tolerance of part 3^2 = 300
Tolerance of part 3 = sqrt(300) = 17.32mm (rounded to two decimal places)

This means that the third component has a tolerance of plus/minus 17.32mm.