Question about Altered Item drawing

[wrkfrm]

Altered Item Drawing definition in ASME Y14.24M-1989 mentioned:
"An altered item drawing shall not be prepared to modify an existing item that was developed by the using design activity.".

I'm having hard time understanding this. Does anyone know what does it mean? And provide some examples if possible.

Much appreciated!

 

[TheTick]

My take...

If the organization has control of the design of the item, then the new drawing (model?) is either a new revision or a new part number and built from zero, not simply adding modifications to an existing part number.

Altered items are changes made to externally-acquired parts, e.g. drilling a whole into a purchased bolt.

 

[3DDave]

"Shall not" seems harsh to me. If an organization wants to make something, run it entirely through QA/QC to accept the final configuration (possibly including paint or plating or assembling to a bunch of other parts)n and put it into a little cardboard box with a label on it - and then take it out of box, throw the box away, and then send the item right back to the machine shop to risk other damages, then they should be allowed to screw themselves over.

It also messes with ERP - the altered item drawing shows the company buying one item to be altered, but to make that item the company has to procure raw materials, maybe do some welding, some machining, maybe some plating and painting, then off to inspection with the components, possibly then to assembly and another inspection - none of this will readily show up in the ERP system unless someone says "Hey, that's our own part." And then, as mentioned before, that only gets them to the starting point for altering the item. It buries costs as the sales price of the item isn't the correct one for altering it like it is for items coming from outside the company.

Oh - if a customer breaks an altered component of an assembly, this can mean they cannot buy a replacement part - the alteration is at the assembly level, not the component level, Some makers do this and it's really annoying - can't replace a $5 pollution control valve - it's integrated into the $1500 intake manifold. There's a potential to force that by using altered item drawings incorrectly.

It's almost always better to just create a new version of the thing, re-use whatever sub-assemblies one can, and fold in the appropriate new parts.

 

[MintJulep]

Fundamentally:

Raw material enters a business.
The raw material is subjected to some form of incoming QA/QC.
The raw material is subjected to manufacturing processed and transformed into a product.
The product is subjected to some form of final QA/QC.
The product leaves a business.

The raw material might be very close to dirt (ore), metal, or plastic etc. stock, a complex finished product of some other business.

The incoming QA/QC might be none ("we trust our suppliers"), or extensive or somewhere in between.

The manufacturing processes used might be simple or complex.

The final QA/QC might be none (some low-cost outsourced manufacturer), or extensive or somewhere in between.

Regardless, every step needs to be defined and documented somehow.

I think this Altered Item Drawing definition is a hold over from the days when the "type of drawing" in part defined the process. It really shouldn't matter any more.

As an example, consider a cast pump housing.

There needs to be a "casting drawing".

There needs to be a "machining drawing".

Should the casting drawing be a different "drawing type" depending on whether you have your own foundry or out source to a separate business?

Either way the casting gets "altered" by machining.

Or, just avoid the whole issue by adding this statement to your policies and procedures somewhere "Selection of external finished products for use and incorporation into our products is a design activity."

 

[ctopher]

It could mean, you design a part, make a drawing.
Now, you want to modify it by adding a feature (i.e. a hole), you make a new part number and dwg to add the feature.
You just altered the part. I have seen this case where both parts get mixed up.
Better to modify the existing part, or add a dash number to it.

Chris, CSWP
SolidWorks
ctophers home

 

[greenimi]

Some clarification, related with this subject, from the 2020 version of the same standard (ASME Y14.24)


Altered Item Drawing (AID):

Description. An AID delineates the physical alteration of an existing item under the control of another design activity or defined by a nationally recognized standard prior to its intended use. The drawing type permits the required alteration to be performed by any competent manufacturer, the altering design activity, or a third party. An AID establishes a new item identification for the altered item.

Application Guidelines. An AID is prepared when alteration of an existing item is required. The current design activity shall not prepare an altered item drawing to alter items they have developed.



Hope this helps somehow....