Family Drawings Revision Help

[FrancoisY]

Hello,

I was wondering when it comes to Casting & Machined parts, how would you rev it correctly if both both are ref. within each other?

Ex:
Casting drawing references Machined part drawing (both are separate drawings but referenced each other). Casting is changing to a new material. Wouldn't it affect the Machined part to rev up also? (NOTE: Nothing is affected with the casting part other than the material change.)

What I think?
Since Casting is the parent to machined (Child), I would assume any changes on the casting drawing, we should rev up for machined drawing.
When I spoke to another design engineer within the company, he stated that nothing is changing dimension wise, part wise, etc. so it shouldn't affect the machine revision.

May I please get guidance? Is there an easy way to memorize how family drawings are affected and how to update accordingly?

Thank you all.

 

[ctopher]

Usually there is a casting dwg, shows material, it's own rev. Machining dwg would indicate "make from" or "material" to be the casting p/n. Material can be shown as reference. Machining dwg also has it's own rev.
The casting dwg may show "used on" to be the machining dwg p/n.

Chris, CSWP
SolidWorks
ctophers home

 

[jassco]

Hi, FrancoisY:

I agree with your colleague in this case. Casting should NOT be the parent to machined part. It is the other way around.

You have a print for your casting. Let's call it "ABC" with its revision;
You have another print for your machined part. Let's call it "XYZ" its revision. "XYZ" is made from "ABC". Revision on "XYZ" is not needed if you don't show material specification on "XYZ". Material specification is an attribute of "ABC" (casting).

Best regards,

Alex

 

[3DDave]

Revisions go up to reflect a minor change.

Part number changes for a change in form, fit, or function.

If the casting is a new material it should have a new part number and the machining, using that new part number will also get a new part number. (however...)

This way one knows which material went into production. The question of what to do at the next level up from the machining is more tricky. If, at the assembly level, the new material doesn't affect how the assembly functions, then you may revise to reflect that either part number is acceptable. Per the above "however" the same may apply to the machining, but for certain there is a need for a new casting part number.

Unless this is automotive where every part is made with a traceable serial number and who knows what they do with assembly level part numbers.

 

[dgallup]

I agree with Jassco. Assuming the new material has passed the engineering requirements and the old material will be used up or scrapped, there is no need for new part numbers. The alteration records will show the history and the ECR will show the reasoning.

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[3DDave]

dgallup - "We checked it and it's just as good" isn't always true and it can be enormously frustrating to have a warehouse of spare parts when some are one kind that work OK and some are another kind that fail dramatically and all of them have the same damn part number.

 

[CWB1]

Agreed with the colleague. The casting print should be the only one with the material spec. The machining ops print is a parent above that and should only reference the base p/n so that all revs are treated the same regardless of material or other minor changes.

Part labeling/marking, revision rules, and PLM statuses are equally as critical as the print structure IMHO, esp with long-life products. Parts should always be labeled with a complete p/n including revision, that's a basic ISO requirement to identify different versions of the "same" part. If your new version is a fully interchangeable replacement on existing products then it becomes a new rev level, otherwise it becomes a new p/n. When you create a new revision dont be quick to apply a cancelled/superceded/other status to the old bc previous revs often need to be kept active with a service-part or other status to ensure the customer is still supported - ie. a new rev of a pump may have different seals, but you still want to sell existing customers the older seals.

 

[dgallup]

3DDave If "We checked it and it's just as good" isn't always true then you have an incompetent engineering department.

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[3DDave]

Yes - that happens, mainly from lack of imagination to check every possible detail. Example - perhaps the original material isn't chloride sensitive; no one noticed that some customers have chlorides in their process. Get new parts in a material that is chloride sensitive and the parts fail. Is it engineering's fault for not knowing what all customer uses could possibly be? The customer had gone through extensive testing to see that the original parts were suitable. Is it their fault when the part number doesn't change for not discovering the material change?

It's the responsibility of engineering not to hide a significant change.

 

[dgallup]

We would have supplied PPAP samples to the customer prior to making the change for them to approve.

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[3DDave]

I've been burned by the "don't change the part number" approach on parts where no one is ever sending PPAP samples.

I'm sure there are industries/components where every application is known to the producer and they are willing for the customers to cancel all contracts when the new part no longer meets their needs and they cannot afford to have their spares be polluted with unusable parts.