Assembly Drawings - Or Instruction manuals

[KENAT]

Here's one I didn't see in any recent posts.

What is people’s common practice for assembly drawings?

By this I mean do your assembly drawings essentially just show the assembled condition with all the information (parts list, notes etc) needed to define it OR are they more like the instructions you get with flat pack furniture from IKEA/Home Depot/Homebase etc?

My principle which my colleagues in my sub department share is that assembly drawing, like piece part drawing, details the finished component and says what is required/what you’ll accept & not how to get there.

ASME Y14.24 seems to support this, although not that strongly it says at 4.1.3 (d) “depiction of the items in the assy relationship, using sufficient detail for id and orientation of the items.”

I’d be interested to hear what others have to say. As part of our trying to introduce drawing/documentation standards one of the things we’re trying to do is get away from assy drawings that double as assembly instructions and instead create true work instructions as required.

We’re facing a lot of resistance, especially from people that perceive this as being extra work and I’d be interested to hear what other people do.

Thanks,

Ken

 

[ctopher]

Assy dwg should only show what parts are needed to complete the assy, with a BOM (either on the dwg or separate). Instruction on how it goes together and what tooling to use, should be on a separate job traveler or some other doc.

Chris
Systems Analyst, I.S.
SolidWorks 06 4.1/PDMWorks 06
AutoCAD 06
ctopher's home (updated 06-21-05)

 

[KENAT]

Ctopher

Now that's what I'm used to (assuming you meant it shows the parts assembled not just a kit) but that concept is completely foreign here and I was trying to make sure that a couple of colleagues and I weren't the ones who were wrong.

When the hole question came up I asked "can't the assembly instructions somehow be put in the MRP/ERP system printed out with work cards or something", e.g. traveler. You should have seen the looks I got.

Ken

 

[MikeHalloran]

There's no _technical_ reason why an _RP system could not store and manage manufacturing instructions in some form. I could swear I've heard of some that do it already.

The _business_ reason that might give one pause is that once those vendors have you by the short hairs, they will extort obscene amounts of money for adding even incremental capabilities. Surely adding process instructions would count as a _major_ "package", with a _major_ invoice attached.



Mike Halloran
Pembroke Pines, FL, USA

 

[KENAT]

Mike,

The MRP system at my last place (can't remember the name but it was old and DOS based with lots of customization by our own IT guys) did it. The instructions were text only but it was the primary source.

For more complex tasks some kind of illustrated instructions would be prepared, sometimes in the form of posters at the workstation, sometimes simplified drawings they called 'work plans' or something like that(which were prepared by manufacturing engineers and weren't part of the formal pack).

I think the _RP vendors probably already have you by the short and curlys once you adopt their system. We've just gone to SAP and I'm not impressed so far.

Ken

 

[ctopher]

I'm used to doing military designs. They require (military) that there be assy dwgs with a separate BOM (or PL) so that it can be inspected, built and easily understood by everyone how the product is assembled. All instructions on how to assemble is also on a separate doc for same reasons above. I don't know how some other companies have been doing it, I know some do not do assemblies or only do assemblies, but ISO 2000 and the military ALWAYS required us to doc everything as I wrote above. When I ref military, I mean USAF, USN, US Army, British Navy, NATO, NASA and others.

Chris
Systems Analyst, I.S.
SolidWorks 06 4.1/PDMWorks 06
AutoCAD 06
ctopher's home (updated 06-21-05)

 

[KENAT]

ctopher

That is the background I'm from and so the standards I'm inclined to apply. I mainly worked on stuff in the UK for the RAF but also army, Royal Navy and USAF. I don't recall manufacturing assembly instructions ever being part of the formal drawing/design package.

I was just trying to find out if in the truely commercial world they'd found a better/more efficient way of doing it but from what I've seen elsewhere and on this thread and I don't think they have. The place I'm at now has plenty of BOM with no drawing and (if your lucky, maybe 25% of the time) an assembly procedure, it's not good.

And at the end of the day standards are standards, if you invoke ASME Y14.5 it would appear you can't put assy instrucions on the drawing.

 

[aardvarkdw]

This is god to know. Our company has been pretty loose with it's drafting standards, when I was interviewing I asked what drafting standards they used and I got laughed at... I've been trying to implement some and have met with mixed results. Not having a copy of ASME y14 here has not helped but I'm working on that. We began eliminating our written proceedures in favor of pictoral assembly drawings in order to streamline our process (combine the two and you have one less document to rev) but, I am seeing that perhaps we are trading one evil for another.

Would the recommended method then be to have a BOM and assembly drawing (no proceedural information, just parts locations) and then have another proceedure drawing? That is what I am hearing. That means one more document to fix but if that is the standard, it is what it is.

 

[KENAT]

aardvarkdw

Before you commit to what is perceived as extra work I'd try and get hold of at least ASME Y14.5 if you can and check you agree with my understanding.

ASME Y14.5M paragraph 1.4 e says "The drawing should define a part without specifying manufacturing methods."

Certainly the standard would appear to me to preclude assembly instructions on assembly drawings, and the samples I've seen that try to do this end up rather unclear as I said above.

We're still bottoming out the recommended method at my place; I think different companies may find different solutions.

The perceived best way here is to have some kind of a formal work instruction, which isn't an engineering drawing itself. That's not to say it shouldn't have lots of illustrations or even be graphically based, one way we're looking at is having step by step assy instructions like the instructions from ikea or an interactive web page generated from the CAD data, but it does free you up from meeting the requirements of Y14.5 etc.

I'm not convinced this is 100% the best way, like I mentioned above I've seen posters at work stations or plain text instructions as part of the _RP system work card/traveler. Certainly the work instructions created here to date take a lot of effort, lots of words with lots of photographs or jpegs of views from the CAD data. Also the 'formal' part means you have rev issues to deal with even though they’re not a drawing, however typically at my place the rev process for documents is less stringent/time consuming than for true drawings.

If there are any manufacturing type bods out there who come across this post, what do you prefer?

Ken

 

[MadMango]

My copy ASME Y14.5M-1994, paragraph 1.4e states in full:

(e) The drawing should define a part without specifying manufacturing methods. Thus, only the diameter of a hole is given without indicating whether it is to be drilled, reamed, punched, or made by any other operation. However, in those instances where manufacturing, processing, quality assurance, or environmental information is essential to the definition of engineering requirements, it shall be specified on the drawing or in a document referenced on the drawing.

So you can have stand alone drawings that detail assembly instructions, or have a separate document, whatever makes sense to your organization.

My organization prefers to have drawings that define the part, controlled by engineering. Assembly instructions and procedures are QA/QC documents (driven by ISO 9001-2000) that are controlled by the ISO 9001 process, section 7.5.2.



[green]"Art without engineering is dreaming; Engineering without art is calculating."[/green]
Steven K. Roberts, Technomad
Have you read faq731-376 to make the best use of Eng-Tips Forums?

 

[ewh]

The key to that quote is "essential to the definition of engineering requirements". Assemble proceedures usually have little to do with, much less being essential to the definition of a part, which is the purpose of a drawing. An essential feature would be the callout of a procedure to install an insert, for example, not "insert screw here".

 

[ctopher]

OOPS! Not enough coffee this morning. I wrote ISO 2000, I meant ISO 9000. Sorry. But, you guys knew what I meant.

Chris
Systems Analyst, I.S.
SolidWorks 06 4.1/PDMWorks 06
AutoCAD 06
ctopher's home (updated 06-21-05)

 

[KENAT]

Thanks ewh.

You stated it much more clearly than I usually seem to manage.

I didn't put the whole paragraph from ASME Y14.5 cause I'm a slow typist and lazy, appologies.

From what I've seen 80% - 100% of what's in (or should be in) the average work instruction doesn't affect the 'engineering requirements' so shouldn't be on a drawing.

Hence separate drawing and assembly process (however you decide to handle the documentation of the assy process).

By the way, I don't think the every assembly needs any more detail then is on a conventional drawing, for simple assemblies I find it hard to believe a separate work instruction is necessary but that is a policy decision that seems to have been made here.

Ken

 

[aardvarkdw]

What are you defining as 'engineering requirements'?

 

[KENAT]

Not quite a definitition of 'engineering requirements' but...

I'm thinking along the lines of:- if the process used to create/assemble the item materially effects the end performance of that item then it should be specified on the drawing.

If not it probably shouldn't.

I think ewh example probably demonstrates it better.

Does that help?

 

[ewh]

To me, engineering requirements are those that ensure that the PART performs in the manner for which it was designed.

 

[MadMango]

Well, to that end, we hardly design just parts, but total systems, yes?

[green]"Art without engineering is dreaming; Engineering without art is calculating."[/green]
Steven K. Roberts, Technomad
Have you read faq731-376 to make the best use of Eng-Tips Forums?

 

[ewh]

Yes, we design systems, but a part at a time.

 

[KENAT]

I would have though that 'part' in this context is refering to whatever the the drawing is of, be it literally a piece part or sometime of assembly.

I tried to think of better terminology but failed.

Ken

 

[aardvarkdw]

Most of the notes that we have been placing on our "assembly drawings", have been along the lines of;

-torque specs for critical features
-treatment of off the shelf bearings (clean and lube)
-orientation and order of assembly of components that are not clear from pictoral or are critical to function.

 

[KENAT]

should be some type of assembly, sorry