Statistical Tolerancing

STAT 498 B

Statistical Tolerancing

Fritz Scholz Spring Quarter 2007

Objective of Statistical Tolerancing

Concerns itself with mass production, not custom made items. Dimensions and properties of parts are not exactly what they should be. Worst case tolerancing can be quite costly. Manage variation in mechanical assemblies or systems. Take advantage of statistical independence in variation cancelation. Also known as statistical error propagation. Useful when errors and system sensitivities are small. It is more in the realm of probability than statistics (no inference).

1

Exchangeability of 757 Cargo Doors

At issue were the tolerances of gaps and lugs of hinges and their placement on the hinge lines of aircraft body and door.

10 hinges with 12 lugs/gaps each.

That means that a lot of dimensions have to fit just about right.

0

................................................................ .................................................................

................................................................ .................................................................

................................................................ .................................................................

................................................................ .................................................................

................................................................ .................................................................

................................................................ .................................................................

0

The Root Sum Square (RSS) paradigm does not work here!

2

IBM Collaboration: Disk Drive Tolerances

H A

S D

B C

3

Coordination Holes for Aligning Fuselage Panels

ideal perturbed holes first hole aligned third hole rotated

4

 ................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download