Should An Interface Control Drawing (ICD) Be One-Sided or Two-Sided? 1

[DavisL]

I'm trying to figure out if our team should use one-sided or two-sided interface control drawings for co-functioning assemblies that are being designed concurrently be separate teams/subcontractors. ASME Y14.24 - 2012 says that "each interface type may be described in a separate interface drawing or in combination on a single drawing." Are there particular cases when you would use one or the other?

I'm leaning towards having separate drawings for each side of the interface to simplify each drawing, allow each design authority to work separately without having to know the technical details of co-functioning items, and for modularity. But then there is no interface control drawing showing how the interface looks when assembled together, and it may be more difficult to keep track of what interface features affect a co-functioning assembly.

Anybody have any advice?

 

[3DDave]

Interface Control Drawings are used to control individual components. Just like one would not put all the detail dimensions of component parts on an assembly drawing so they could be copied to other component drawings, there's no need to do the same for an ICD.

It is up to project/program management to ensure that all the components of a project/program fit and function together. If someone changes the interface of a component they need to make sure the change is relayed to everyone who depends on that interface just the same as if there was no interface drawing at all, and only detail part and assembly drawings.

Showing components fitting together is done on the assembly drawing. Knowing that the fit is correct is done by analyzing the relationships of those components to each other.

See

https://www.eng-tips.com/viewthread.cfm?qid=235979

 

[MintJulep]

What that ASME sentence means is that you can have separate drawings for (for example)

Mechanical interface.
Electrical interface.
Hydraulic interface.
Pneumatic interface.

Or you can put them all on one drawing.

 

[monkeydog]

It sounds like you need 3 drawings.
1) ICD that defines the "left side" interface requirements from supplier A
2) ICD that defines the "right side" interface requirements from supplier B
3) Your assembly drawing that installs/connects both sides to your box.

 

[DavisL]

Thank you everyone for the responses. It seems like responses so far are saying one ICD for each side of the interface. I work for a large aerospace & defense company, and at least one of our well established programs uses two-sided interface control drawings, and I'm having a difficult time convincing my team that it may be better to do only one side per drawing.

To add to the complication, sometimes an assembly has to interface with multiple assemblies attached to it, which would require a separate drawing for each interface. Having one drawing that defines all the interfaces for the assembly would be simpler in my opinion.

Can anyone offer any reasons why you might want to have a two-sided ICD? ASME Y14.24 allows for both methods.

For some more context, I'm working in a small, developing program with the flexibility to make those decisions at the program level now.

 

[monkeydog]

Will sharing/showing the other supplier (competitor) interface reveal any of the other supplier (competitor) proprietary information?

 

[SwinnyGG]

Can anyone offer any reasons why you might want to have a two-sided ICD?

I have a hard time imagining why you would NOT want both sides of an interface on the same drawing.

Thinking mechanically for simplicity sake. If my interface for two parts is a bolted flange, controlled by an ICD, and I change the diameter of the bolt pattern or the size of the bolts, single-sided ICDs mean I have to rev two drawings instead of just one. Multiply this times the number of interfaces in a large system and this doubling of drawings (and drawing numbers and references and all other ancillary labor induced when a new drawing number is created) can become a very large amount of engineering hours spent. Each additional drawing number that requires maintenance is also an additional process step for which mistakes can be made.

 

[MintJulep]

ASME Y14.24 allows for both methods.

No. It does not.

It quite clearly requires that one drawing ("an interface drawing") show the interfaces of "related or cofunctioning items". "Items" is plural. "an interface drawing" is singular.

What is allowed is separate drawings for each "type" of interface. With an explicit list of types being provided.

An interface drawing depicts physical and functional
interfaces of related or cofunctioning items. It does not
establish item identification.

...

An interface drawing may control one or more of
the following types of interfaces: mechanical, electrical,
hydraulic, pneumatic, interconnections, configuration,
installation, operational sequence requirements, system
switching, etc. Each interface type may be described in
a separate interface drawing or in combination on a
single drawing.

Having separate drawings for each side of an interface is the exact opposite of having an "interface control drawing". Avoiding this situation is what interface control drawings exist to prevent.