Form/Fit/Function vs. Minor/Major Revision - Definition

Hi,

I have a client who wants to know if there is a standard to define
major/minor revisions and how do you determine it using Form Fit
Function.

He says everyone uses it but nobody can refer him to a standard
reference that spells this out in black and white.

How does your company deal with these issues?

Len

 

Hello towards you Mr. Len.

The revison of the minor types are if or why the parts can be used in a
backwards fashion.

So while the new part can be made to substitute on the old part it is a
minor revision to make.

But for to make the major revisions is to make parts that become not
backwards campatability.

So when new part is compatible with exsisting already parts it is small
revision but if not backward compatible then it became major.

This is the primariey differences to think upon.

Thank you very much please,

Habib

 

Len,
Here are my responses:

ASME Y14.35M-1997 "Revision of Engineering Drawings and Associated
Documents"
This specification defines evrything you need to know about the
Revisions including Form, Fit & Function.
Form: The shape, size, dimensions, mass, weight and other physical
parameters
which uniquely characterize an item.
Fit: The ability of an item to physically interface or interconnect
with or
become an intregal part of another item.
Function: The action or actions which an item is designed to perform.
Whereever I have worked an EO (Engineering Order) always has a
clasification
which basically stated a Conditio or Type as in I or II:
Type I: Interchangeability, Form, Fit or Function are violated.
Type II: No effect on Interchangeability, Form, Fit or Function.
Usually
clerical error, minor corrections, typos, etc.

If the reference to the above is to the classification, then this is
covered
in the ASME spec. If this is not what you are referring to then my
only other
guess would be that they are making reference to Minor/Major
Characteristics.
If this is the case than they are talking about Quality Inspection
Levels or
AQL's, for this, see MIL-STD-105. Using this standard, any aspect of
any item
defined on a drawing can be classified as Minor, Major or Critical
100%
inspection required.
Hope this clarifies things,
......................................Eddie