I disagree.
Most places I have worked have separate BOM and assembly drawing
revisions. The documents are independent of each other.
The reason for this is because the BOM is seldom a static document. It
undergoes changes on a regular basis.
Every Engineering Change Notice/Order has a significant cost. For every
ECN someone needs to update the BOM, update the configuration list,
update the schematic drawing, etc. etc.
Demanding that the assembly drawing maintain the same revision as the
BOM means that you have just doubled the price of every ECN.
Unfortunatly the schematic must be updated every time the BOM changes,
as the component values must be updated on the schematic. Adding the AD
to the list just adds cost. Look at it this way; there is a circuit that
is attached to the assembly. Changing something on the circuit does not
change the assembly. If changing something on the circuit demands a
change to the assembly, then the assembly revision should be updated as
well. But if changing something in the circuit does not change the
assembly configuration, then no change need be made to the assembly
drawing, thus no change to the revision.
I....must learn...to
accept....change....because...nothing.....ever....remains...the...same.
Must....learn..to manage...methods...that...make sense....economically.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Phil Nutting
Sent: Friday, October 07, 2005 12:23 PM
To: [log in to unmask]
Subject: Re: [TN] Assembly Documentation Question
Michael,
My experience and preference is to have the BOM and assembly drawing
match in revision. If they don't match who is going to maintain a
matrix explaining what document goes with another document.
Does your BOM call out the revision of the assembly? If so wouldn't you
have to uprev the BOM to reflect the change in revision of the assembly
print?
We experimented with making "dash" prints where we started with a
"generic" design with a -X suffix and then for subtle changes made -1,
-2, etc. assemblies but all based upon the -X print. You wouldn't
believe the confusion this caused at outsource vendors and our
revisions. Imaging the problem when the assembly print and BOM revs do
not match.
I... Can... Not... Change! Must... Do... It... the...way... I...
Have... always... Done... It!
Wow that was close.
Phil
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Michael Kuczynski
Sent: Friday, October 07, 2005 12:19 PM
To: [log in to unmask]
Subject: [TN] Assembly Documentation Question
The company I work for is going thru some documentation change
discussions.
Below are the documents that are revisable. (The parts list contains all
the IC's, cap, res. etc. and documents.) The feedback I'm getting is the
the parts list and the assembly drawing should ALWAYS be the same
revision (becasue thats the way its always been).
Everywhere I've every worked, these are independent documents.
Here are my scenerio case: (All documentation released at Rev. A)
Scenerio (Rev: B): A part number change, of a 1K, 5% resistor to a 1K,
1% resistor.
In this case, the part list and schematic would change, but it has no
effect on the assembly (because no part number or value is on the
assembly drawing).
PL1234567-1 Rev: B Parts List
AW1234567 Rev: A Assy Dwg
DS1234567 Rev: A Drill Dwg
PC1234567 Rev: A Artwork
PA1234567 Rev: B Schematic
Scenerio (Rev: C): The length of the screw holding the stiffener bar is
changed from 3/8 in. to 1/2 in.
The change is to the parts list only, the assembly drawing stays the
same.
(no 3D view or side view)
PL1234567-1 Rev: C Parts List
AW1234567 Rev: A Assy Dwg
DS1234567 Rev: A Drill Dwg
PC1234567 Rev: A Artwork
PA1234567 Rev: B Schematic
The current discussion and question is;
-Can the parts list be independently revisible, from the assembly
drawing?
-What do most of the assembly houses usually like?
Thanks for any response to this question.
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