Drawing revision issue/problem 1

[thepdlr]

I have a injection molded part with a part number that cannot change. Let's call it part ABC rev B. I'm currently having a new tool made for the same part. I don't want the existing vendor to know I'm second sourcing the product/part so I cannot add a chart or table to the existing print. Plus, since the current part is rev B i cannot make the new part rev A. How do I handle 1 part with various revisions? an the new part be revison AA?

 

[swertel]

I think you need to define your problem better, or at least explain it here.

Why do you need to add a chart or table to the existing print to change vendors?

Why are you talking about going back a revision, to rev A?

Can't you just give your new vendor a copy of your part ABC rev B for him to quote?

Why can't you just revise the current part to Rev C and give that to your new vendor? Who says you have to give a copy to your current vendor during sourcing? You could revise the print and mark it preliminary and work with the prelim print until you finish your sourcing tasks and can officially release it.



--Scott

For some pleasure reading, try FAQ731-376

 

[swertel]

Now for some guesses at answers.

Revisions are not for configuration control. If you revise a part, it should be completely interchangeable with the previous revision of the part. If it is not, then you have to create a new part number, not just a revision.

You deal with two revisions through their corresponding effectivities. Effectivities can be by date, by program, by contract or PO, or by serial or lot numbers. You can have two revisions that are both active at the same time, but it gets very confusing when dealing with the product baseline.

--Scott

For some pleasure reading, try FAQ731-376

 

[thepdlr]

I still don't have a valid option. I could revise the existing print to C and consider it as the new drawing for the new part. Although this will not work because it's possible that the old tool/part could still be revised or updated prior to the new tol being released. This could easily be handled with a chart which denotes the various dimensinal differancs allowed for the given tool but this will not work right now. I do not want the new vendot to know about the new tool until it is omplete & online. One option I'm considering is to stat the new part as a rev D or E which will allow the old part to be updated if necessary.

 

[MadMango]

You are only asking for future trouble by trying to manage your vendors through your revision levels.

Bite the bullet and create a new part number for the new part that defines your new dimiensions and tolerances.

[green]"Art without engineering is dreaming; Engineering without art is calculating."[/green]
Steven K. Roberts, Technomad
Have you read faq731-376 to make the best use of Eng-Tips Forums?

 

[thepdlr]

I wish. No-can-do. The Sales & Production Control Departments will never allow it.

 

[swertel]

Do you have a Deviation or Waiver procedure in place?

The way we work out "development" changes to a production part is to create a Deviation. This Deviation applies strictly to a specific revision. In other words, you are currently at RevB. You create a Deviation against RevB and give your new vendor the RevB drawing and the Deviation. He quotes to that and makes the tool to both the drawing and the Dev.

In the meantime, Supplier 1 is still happily in production and making changes to RevB. To document these changes, you revise the drawing to RevC.

Now the tricky part. Supplier 2 is working to RevB+Deviation. You can either update his SOW with RevC + a new Deviation, or keep going as is. Once he is online, you give him RevC to work to because it is now your active rev. Or, depending on the content of the Deviation. You revise RevC to RevD and Supplier2 works to RevD. Supplier 1 is effetively out of the loop.

This is very similar to the way the government handles NORs (Notices of Revision). Basically, the contract states create to drawing RevC and NORs 1, 3, and 4. Another contract may be just to RevC. Other may have other NORs. When the government finally revises their drawing to RevD, all the current NORs get incorporated. It's confusing, a real PITA, but it works and saves money but not having to go through the ECO process to correct a typo.

--Scott

For some pleasure reading, try FAQ731-376