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.

 

[KENAT]

Michael, we do a lot of that stuff, but in assembly work instructions or routings etc. Still fed from the same 3D model but not the drawing.

I could write a long diatribe on the issues we've faced trying to create work instructions based on CAD data before finalizing that CAD data/drawings but I can't be bothered right now.

KENAT,

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

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

 

[bf109g]

So what you're saying, Michael, is that it will no longer be necessary to read an honest blueprint on the shop floor?

I guess I need to ask for a raise since I will be doing tech pubs work in addition to my engineering duties. The company could afford it since there will be no need to pay technically competent people in the shop. Anybody can come in an assemble parts based on the funny paper simple exploded drawings that will be beside each workstation.

As an aeronautical engineer, that scares me. I realize that for some, engineering has become a repeatable process where only the process gets attention and there is no technical expertise required. Where is the accountability? What if the process is flawed in a major way because some ISO certification guy just showed up one day and got taken to lunch and boozed up, after which he signed the certificate? No sir, this ISO/system/process stuff can be dangerous and we need to be ever vigilant to make sure that "approved" processes and procedures don't end up killing someone.

 

[SDETERS]

I do not think it is all about reading or not being able read Blueprints on the floor I think it is a better communcation tool than a cross section showing only a 2D view of what is being assembled. We have the technology to show animations 3D parts lets make it more clear than ever to get the parts assembled correctly.

 

[PeterStock]

The intent of a drawing is to communicate. An exploded iso, or possibly an animation of how an assembly goes together, is a better form of communication with the assemblers. Other people may need other views for there needs.

Peter Stockhausen
Senior Design Analyst (Checker)
Infotech Aerospace Services

 

[drawoh]

bf109g,

On my site, my boss is demanding exploded views because production likes them.

Somewhere in my design documentation, I want orthogonal views with section views and whatever else is need to under what it looks like and how it works. Often, I do this on a separate arrangement drawing.

My perception of the assembly drawing is that it tells someone how to put the thing together. Assembly sequence, test procedures, orientation of components like belleville washers, and screw torques are as much a part of the design as the intended functionality.

JHG

 

[KENAT]

As someone who routinely has to work with Assembly drawings, trying to work out what the end item is rather than how to achieve it, I can vouch that the multiple exploded views or step by step sequence is much slower to work with than a conventional drawing, and often omits certain information.

I'm sure it's better for shop floor, but sucks for at least some other users.

That's why I believe exploded views, within reason, should be in addition to views that explicitly show the assembled state.

Also, I still can't help but think the principle of detailing the end item applies.

KENAT,

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

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

 

[bf109g]

+1 Kenat.

I've never seen an assembly that couldn't be fully depicted with auxiliary and section views. I have yet to see a major aircraft manufacturer depict an assembly as an exploded view as part of an FAA approved data package.

Shop documentation is another thing. If the shop wants an exploded view to assist in assembly, do whatever makes them happy. Add it to their traveller. Hold their hands to make sure the -1 goes against the -3. But when final inspection is accomplished on an FAA approved design, it must be checked in accordance with the FAA approved data.

But again, we are dumbing down our engineering documentation to cater to the lowest common denominator. I just don't like it.

 

[ewh]

If photographic documentation is allowable by the standards, I find it hard to believe that exploded assemblies (without any orthographic views) would be prohibited.

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

 

[KENAT]

bf109g that's my line of though, have separate work instructions/travellors whatever you call them with most of the exploded views, photos etc.

However, in the commercial world especially, there's the assumption that extra documents mean extra work/cost and money can be saved by combining them in a single document. I'm not sure that's always completely true, but I'm getting tired of arguing the case. Hence I'm about to put a bunch of photos, that depict things already shown in a true drawing view as well as step by step instructions (in contravention of 14.5) on what was a nice clear assembly drawing.

ewh, I'm not sure anyone has stated exploded views are prohibited. The contention as I understand it is whether they can be used by themselves.

KENAT,

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

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

 

[ewh]

That is why I qualified my post with "(without any orthographic views)". I think we've already established that thay are allowable in some contexts.

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

 

[KENAT]

Photographs may be showing the assembled state, which meets the requirements of ASME Y14.24, 4.1.3, I still don't think an exploded view meets those requirements.

KENAT,

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

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

 

[ewh]

I wasn't trying to infer a connection between assemblies and photos, just the fact that such liberal documentation methods are allowable in some situations but not others.

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

 

[bf109g]

How does one put tolerances on a photograph or exploded view?

Man, I didn't think I'd open up a can of worms like this...

 

[ewh]

A Sharpie?
Time to break out those poles!

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

 

[KENAT]

Dimensions on assembly drawings, that's crazy talk.

No,no, no, no, no - we want vague un inspectable requirements like 'approximately centered as shown in the beutiful photographs'.

Of course, as the OP seems open to veering off topic, a lot of this issue is related to de-skilling the shop floor.

Most on the shop floor can't read an engineering drawing. I thought this was where production/manufacturing/industrial engineers came in and filled the void by translating Design's requirements into the required steps to achieve those requirements. Be this as a traveller that follows the job, work instructions, fancy 3D CAD animations, cartoons, placards, specific task oriented workstations & training... Trouble seems to be, managers want to get rid of the skilled labour, without getting enough/any manufacturing engineers that can translate the drawings. Hence you end up with these abortions of so called assembly drawings.

[Sorry, I'm in a bad mood about that drawing still]

KENAT,

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

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

 

[ewh]

Which drawing was that?

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

 

[bf109g]

Heck, some of our machinists can't read a drawing, as evidenced by some late night panic calls to yours truly.

You're right, there is a definite movement afoot to clear the decks of all skilled workers on the shop floor. I won't be politically incorrect by mentioning that I need an interpreter to converse with some workers, but there I went and did it.

 

[KENAT]

My 2 Mar 09 15:01 post.

It wasn't even my @#$%#$%@# drawing in the first place. It was a pile of #$%#$% I picked up from an intern and made legibile. Then every other day they come up with some other requirement they forgot to specify that needs adding, it's now culminated in so many extra notes and photo's that it really needs an assembly procedure not just a drawing, but they don't want to do that, even when I offered to do it. They even made me take off the nice clear dimension;-(. I'm off to complain ineffectually to my boss about it.

KENAT,

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

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

 

[ewh]

Sorry, I missed that... Oh man, I feel for you. I really hate it when I'm asked to be a cartoonist. That's just about the worse insult you can give a good drafter/designer.

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

 

[drawoh]

bf109g,

As a general rule, exploded views are unsuitable for dimensions. An orthogonal view is much more suitable for this purpose. If it reaches the shop at 1:1[ ]scale, it can be used as an assembly fixture.

Parts that attach solidly together do not require assembly dimensions. Parts that will be adjusted in some later process should be assembled to a nominal dimension, plus/minus some tolerance.

Drawings are a means of communication. You apply the views that communicate the required information. Systematically apply exploded views is just as limited as not ever applying exploded views.

JHG