O.T. Revision changes

Slightly off topic but, I am wondering if most of you make a revision
change to a higher level assembly or weldment when a sub-component is
revised? I work for a job shop and some of our customers do make a rev
level change and some do not (and quite a few are not consistent) when
changing sub-components.

In general, I normally don't change the higher level revision, unless
by changing a component a functional change has been made to the
weldment or assembly - adding a new feature, changing the application,
etc.

Your thoughts are welcome, and if anyone knows if a standard covers
this it would be welcome as well. We are in pursuit of ISO registration
and are reviewing our rev control process, and debating whether to use
internal revisions as well as the customer revisions to control
documents. We also got bit by this from a major customer who changed
material coating on components without processing an ECN. The parts are
painted and we only recently found out they were changed from plain
steel to a paintgrip galvanize.

Thanks for any input, Diego

 

The rule is form-fit-function (f/f/f) in conjuction with
interchangeability. If your lower level changes affect the
form-fit-function of the higher level assembly, then you need to revise
the higher level assembly, otherwise do not revision the higher level
assembly. Be sure to understand how you want to implement this rule.
Some may apply this rule to mean that only actual f/f/f changes to the
higher level assembly will trigger its revision. Others may say that
simplying affecting the f/f/f triggers the revision. ("Affecting"
being a broader category than "changing")

Interchangeability goes into whether to pull new part numbers or not.
If at any level your revision is not interchangeable with previous
revisions and visa versa, then the new revision of the part should have
a new part number.

The company I work for is ISO reg, and I've written a pretty good
revision control procedure for it that covers this. If you are
interested, I'll email you some of the wording.

Matt

 

The rule is form-fit-function (f/f/f) in conjuction with
interchangeability. If your lower level changes affect the
form-fit-function of the higher level assembly, then you need to revise

the higher level assembly, otherwise do not revision the higher level
assembly. Be sure to understand how you want to implement this rule.
Some may apply this rule to mean that only actual f/f/f changes to the
higher level assembly will trigger its revision. Others may say that
simplying affecting the f/f/f triggers the revision. ("Affecting"
being a broader category than "changing")

Interchangeability goes into whether to pull new part numbers or not.
If at any level your revision is not interchangeable with previous
revisions and visa versa, then the new revision of the part should have

a new part number.

-Matt

 

Just as followup, here's the definitions I've pulled together for fff:

Form, Fit, or Function (FFF) - Characteristics of physical items.
Form - Item material, composition, or general shape.
Fit - Item size, mating, mounting, attachment, or connection.
Function - Item purpose, operation or performance (such as: method
of use, operating range, safety, compatibility, reliability, accuracy,
etc).

 

Thanks Matt. That's what I was looking for.

 

One of the things I have had to do in the past was to include the
revision in BOM's of the pieces parts. Unfortunately, doing this
forces you to revise the entire assembly chain from the lowest
component revised. It's tedious, but frankly is the only real way of
keeping track of revisions without a PDM.

chris