Acceptable to have assembly drawing an exploded view?

[bf109g]

Hi all.

I have a high level question regarding what an assembly drawing should be. To me, an assembly drawing should be a three view of the assembly, with auxiliary views and sections taken as appropriate.

I have a designer (technically my boss) who insists on making his assembly drawings as exploded views. I understand why he does this from a business standpoint (we don't really have a tech pubs dept.), but as an engineer, it just rubs me the wrong way.

Anybody have any experience with using exploded views as the engineering assembly drawing? I'd like to be able to point to something and say it's a no-no.

Thanks.

 

[MintJulep]

Is assembly a noun or a verb?

 

[bf109g]

Noun.

 

[ewh]

Yes, as far as I can discern it is allowed.
Per ASME 14.24-1989 (may be a later revision by now), para 1.4 "Preparation methods... (orthographic, pictorial, or exploded views)... are a concern of this standard only to the extent that the drawing satifies its intended purpose."
ASME Y14.100M-1998 states in para 4.9 that "Isometric or pictorial views shall be in accordance with ASME Y14.4M, and may be shown on engineering drawings provided that clarity is not degraded."
I don't have a copy of Y14.4M, but doubt that it would restrict their use.
I'm sure others will add to this.

"Good to know you got shoes to wear when you find the floor." - [small]Robert Hunter[/small]

 

[fcsuper]

I have Y14.4M. Exploded views are indeed mentioned. Y14.4M allows a great many types of views, even actual annotated photographs can serve as the drawing. Using photos to show assemblies was actually my biggest question in this topic before I bought the standard.

bg109g, you might be thinking of "level 3" (if I remember the name correctly) drawings that show a tremendous amount of detail of parts and assembly in very particular formats. This is not part of ASME standards; I think its a government requirement for particular contracts.





Matt Lorono
CAD Engineer/ECN Analyst
Silicon Valley, CA
Lorono's SolidWorks Resources
Co-moderator of Solidworks Yahoo! Group
and Mechnical.Engineering Yahoo! Group

 

[ewh]

Thanks, Matt. I do remember seeing somewhere that annotated photos were allowable, though I have never seen it in practice.

"Good to know you got shoes to wear when you find the floor." - [small]Robert Hunter[/small]

 

[MintJulep]

If the intended purpose of the drawing is to depict what the finished assembly looks like then I'd go for non-exploded.

If the intended purpose of the drawing is to depict how the thing goes together then I'd go for exploded.

There is no reason you can't do both on the same drawing.

 

[ctopher]

I agree with the others. Drawings are to depicts how the assy goes together. If it requires an exploded view, then show it. But, I would never show only an exploded view. The only areas that I have shown only exploded views are sometimes on job travelers, marketing brochures, or for customers that request it.

Chris
SolidWorks/PDMWorks 08 3.1
AutoCAD 08; CATIA V5
ctopher's home (updated Aug 5, 2008)
ctopher's blog
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[MadMango]

I will chime in, exploded views are allowed. As MintJulep said, it really depends on the purpose of the assembly drawing. If the exploded view does not add clarity, then it shouldn't be used.

As for photos, when digital cameras because affordable (circa 1996?) I worked at a place that began to use photos for some wiring harness details. The problem quickly arose after seeing a drawing copied and/or faxed. It took several months for people to decide which gray scale setting they would use so the inserted photos would survive a few copy/fax actions. Very ugly.

"Art without engineering is dreaming; Engineering without art is calculating."

Have you read faq731-376 to make the best use of these Forums?

 

[ctopher]

I'm against using photos on drawings. I have only seen problems with them when others start copying them. They are good on documents for viewing purposes on a monitor only.
I once worked with a company that decided to make one whole project with photos of it instead of taking the time to draw it. The drawings were full of these wonderful photos. Then the customer received them and could not make copies and reduce them to smaller sheets, the photos turned black. If any changes were needed, new photos were needed, but then that specific product was shipped, the current ones were slightly different because of design changes.

Chris
SolidWorks/PDMWorks 08 3.1
AutoCAD 08; CATIA V5
ctopher's home (updated Aug 5, 2008)
ctopher's blog
SolidWorks Legion

 

[aardvarkdw]

As long as an assembly drawing shows all components in their final position and orientation, and accurately describes the finished product all criteria are met. If an exploded view helps show exactly what a component is and where it goes, good, but you must show it in it's final position as well.

The other side of this is that you should NOT be telling someone how to build the assembly or what methods they should be using. These should go in an assembly instruction document.

David

 

[bf109g]

Thanks for the input. I'd agree that an exploded view should be a supplement to standard drafting data, and not as the sole depiction of the gizmo.

 

[ewh]

I don't think that there is a hard and fast rule that an assembly MUST be shown in the assembled state, but agree that it is a very good practice to follow. Unless I actually see "will" or "must" in the standards, I try to avoid absolutes.

"Good to know you got shoes to wear when you find the floor." - [small]Robert Hunter[/small]

 

[bf109g]

Not only that, but it's always a good idea to check a few pertinent dimensions after assembly. Especially if you have similar assemblies which differ in one or two critical dimensions.

How do you dimension an exploded view? I've never seen it.

 

[SDETERS]

All of our Assembly Drawings are Mulitple sheets. We have the Exploded ISO on the first sheet of all the parts and on the other sheets we show the dimensions of the assembly where needed. The Exploded view helps the person on the assembly line to see what the part looks like and where it goes in the assembly. It is hard to see the shape of a part just by a cross section or multiple views if you are not trained in blue print reading or have limited assembly views.

 

[aardvarkdw]

ASME Y14.24, 4.1.3 Requirements. An assembly drawing includes as applicable, d) depiction of the items in the assembly relationship, using sufficient detail for identification and orientation of the items.

In my opinion, an exploded view, by itself, cannot show the correct assembly relationship and orientation for the simple reason that the parts are not attached in the view. Don't get me wrong though, I think exploded views are great for communicating information. In some instances an assembly becomes too complex to be clearly communicated by sections and auxiliary views alone. I just think that you need to also show the final location of the parts as well.

David

 

[ewh]

I think we agree on most of the points you bring up, David, except that I think, under certain circumstances, an exploded view can show the "depiction of the items in the assembly relationship, using sufficient detail for identification and orientation of the items", thus there should not be an absolute prohibition against using only exploded views.
That said, I don't think that I have ever created such drawings without showing the assembled state and would not recommend it. I feel that an assembled view is essential to show what the envelope actually is and what the assembled part will look like.

"Good to know you got shoes to wear when you find the floor." - [small]Robert Hunter[/small]

 

[fcsuper]

I've used exploded views only for assmeblies where the final product does not represent noted componentry (such as assy where everything falls inside two or three parts and where a section view would be more confusing than helpful. Use of those connector lines can be enough to provide info on what goes where.

Matt Lorono
CAD Engineer/ECN Analyst
Silicon Valley, CA
Lorono's SolidWorks Resources
Co-moderator of Solidworks Yahoo! Group
and Mechnical.Engineering Yahoo! Group

 

[KENAT]

I'm actually with aardvarkdw on this one. I don't believe just an exploded view by itself is adequate, since it doesn't define the end item which is a pretty fundamental principle of most drafting. Also I believe 1.4(e) from ASME Y14.5M-1994 still applies, so the drawing shouldn't really be showing how to put the item together.

While the wording of 14.24 may not be as clear as it could be I agree that "depiction of the items in the assembly relationship, using sufficient detail for identification and orientation of the items." means showing the final assembled condition.

However, exploded views are allowed as other have pointed out, but I'd only use them in addition to assembled views when they add clarity.

I asked a similar question some time ago: thread1103-157857 and I think there may be another thread too around that time.

KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at posting policies:

http://eng-tips.com/market.cfm?

 

[Michael854]

Gentlemen,

Other product development activities are moving toward requiring exploded view drawings. Hopefully, the ASME standard can keep up.

Look at the future assembly plant...beside EACH workstation will be an exploded view drawing of some sort.

Drawings of the future will be used to do more. Example...There will be "in-process" drawings used to do things like "kit" parts...to aide in error-proofing.

As processes like FMEAs grow in importance, so will new unconventional looking drawings.

Michael