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

 

[MadMango]

We create CAD exploded assembly drawings for mechanical assemblies. These are used by the assembly line to build our products and are also used to create images in our manuals for service and repair part ordering for our technicians and customers. If there are specific assembly steps or requirements (bolt torque or lubrication) we create work instructions that utilize digital photographs.

Weldments are shown in the assembled condition. We also have application drawing sets, these show our products in the assembled condition as well, and define all mechanical and electrical interfaces for our customers.

[green]"Art without engineering is dreaming; Engineering without art is calculating."[/green]
Steven K. Roberts, Technomad
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[ewh]

We will also create exploded assy dwgs, but do not define the proceedure for assy in those dwgs. The exploded views are to clearly define what component goes where, not how to get there (as stated in ASME Y14.24 P4.1.3(d)). There are separate work instructions to be followed to ensure correct assembly.

 

[aardvarkdw]

We had a shortage of drafters for several years and were forced to do most of our assembly documentation in proceedure form. This worked but it was hard to get good photographs that conveyed the information clearly. Also we had a hard time with written documents not being used because people didn't want to read a 10 page document telling them how to properly install a part, consequently things got assembled improperly. Now due primaily to requirements from one of our distibuters, we are using exploded view drawings for assembly manuals (Sort of "Ikea style" for our complex assemblies). This allows us to get the information across to not only our employees that may not read english very well but also to our distibutor's foreign service engineers.

" 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.", I agree, with the caveat that sometimes assemblies are too complex or large to detail properly in assembled form and on a single sheet. We don't tell our people in our drawings what tools to use or how to do an operation unless it it has special requirements that may not be intuitive.

 

[KENAT]

Thanks for the responses.

Just to clarify I’m not saying that the assembly drawing should be just a single sheet with just a parts list and a ballooned orthographic view.

All the views necessary to fully detail where parts end up should be there. My preference is first try and do it with ortho views, then sections then views with certain items hidden and explosions as a last choice. If multiple sheets (or my preference one large sheet) is needed so be it. I was also taught not to balloon/detail on iso views but am not sure I can justify that from the standard.

My concern with using exploded views as primary views in a drawing is that you’re not really showing where the part ends up, typically you’re showing it out of position with a ‘flow line’ to where it ends up. Also certainly in our CAD system good explosions can be time consuming, especially maintaining them after revs (supposedly improved at the next version).

I strongly support the use of exploded views in work instructions (assembly manuals etc) and generating them from the cad data makes a lot of sense and is something we do and are looking to improve. However I feel they are of best use in this type of document not in the controlling drawing. From my experience it’s relatively rare that you can show something in an exploded view that you can’t show in a section or one of the other types of view I list above.

I agree that wordy assembly documents can be hard to use, we currently emphasize use of pictures and are working on getting those images from CAD data rather photographs.

Any more opinions/comments would be appreciated.

Ken

 

[aardvarkdw]

I have found that many people can't read an orthographic drawing and have a hard time visualising part locations from a section veiw. We use Inventor and it has worked pretty well for us, it could be better but such is life. I always try to put a fully assembled veiw on the first page or if the drawing is only one page, in an upper corner. I agree that if the assembly is not shown complete the drawing can be next to worthless.

 

[namdac]

Here I will give my two cents worth:
1.) are the pieces drawn in 3-D?
2.) If drawn in 3-D, then time is to make the exploded view will be shortened.
Be sure that when you show an expolded view use phantom lines when necessary to show assembly.
Then if there are any revisions they will automatically update as long as you remember to use Xref(AutoCad) or References (Microstation) or my fav symbolical in Drafix.
It's not really that hard to show your "Client" the item you propose.
Regards,
Namdac

 

[KENAT]

Namdac, thanks for the response.

1. The assemblies are modeled in Solid Edge (3D CAD, no not a version of Solid Works incase anyone didn’t know).
2. A default explosion can be generated very rapidly (about 3 mouse clicks if I recall) unfortunately this default explosion is not usually adequate and requires editing.

You’re generally right about showing phantom ‘flow lines’ as I noted in an earlier post. Sometimes however they can create a cluttered drawing, especially when you try to do too much on one view.

The problem in revving comes if one of the ‘lower level’ parts in the ‘explode tree’ type functionality is replaced by a ‘dissimilar’ part. This causes large sections of the explosion to collapse or otherwise fail. (Essentially I believe because you’ve changed to original assembly constraints.)

It would appear that at the next software release they’ve improved the explode environment somewhat which should speed this up however slow generation of explosions wasn’t my main concern.

My fundamental concern is not so much whether explosions should be the primary method of display on the assembly drawing (though I’m inclined to think not) but as to whether the assembly drawing should double as an work instruction giving detailed instruction in how to assemble the item.

From what I’ve seen here this leads to a cluttered drawing which still doesn’t really have a full set of assembly instructions and yet, because primarily exploded views have been used, can’t really be used to check that the part was assembled correctly.

I think aardvarkdw has hit the nail on the head. With the phasing out of truly skilled labor the people putting the item together often can’t read a conventional drawing. This is where I thought manufacturing/production engineers were meant to step in and take formal design documentation and come up with process etc to simplify this for the production line maybe I misunderstood. (Yes I know not all companies have the resource for dedicated manufacturing engineers etc. but I mean the principle.)

Ken

 

[ewh]

Ken,
I strongly agree with your rational. I have done exploded assy dwgs, but that is not my preferred method. Sometimes we are constrained by situations out of our control, such as shortages of labor, budget, and the most common - time. It can save hours in work instruction and proceedure illustration to use exploded views.
Bottom line, you are correct that orthographic and section views can define nearly every assembly (I can't think of any exceptions, though), and the product is better defined using that method.

 

[thundair]

Ken
We use MDB (model base definition) and do not have any drawings. This is for Airbus & Boeing alike.

The planning is similar to what Aardvark posted and is the only paper that is generated from the MBD....

There was somewhat of a struggle with manufacturing but that was only in house. The vendors seem to jump on board pretty quick.


The assy is handled by M.E.'s and their planning which include illustrations relative to the assy level or process.

Cheers

 

[MikeHalloran]

I have on a few occasions generated an entire tree of assembly and subassembly drawings, and had to re-do them to match the sequence of the build process, and re-do them again every time we got a new manufacturing manager who re-"engineered" the process his way. It was really aggravating. It would have been much easier if "re-do" didn't involve erasers and pencils.

Eventually, CAD made it nominally easier to do stuff like that, but CAD was paid for by shrinking staff, so it really wasn't any easier or quicker.

Then, JIT came along, and did away with any necessity for 'structure' in bills of material, or assembly drawings.

On the other hand, the 'manufacturing instructions' associated with JIT are in the aggregate much more detailed than any assembly drawing/ BOM for a product of similar complexity. I don't know if CAD models could help make them more easily; ours were generated by 'artists' who had no idea how to import a CAD file even if they wanted to, and they didn't want to, because they were paid by the hour.

JIT was a net positive for the company, but doing it for the first time was painful.





Mike Halloran
Pembroke Pines, FL, USA

 

[KENAT]

Thanks ewh I couldn’t think of any exceptions either but knew if I said there weren’t any someone would find some.

Thundair I really should learn more about MBD and how it deals with all the obvious pit falls that I immediately think of when I here the term. Obviously more and more companies are doing it and there is a standard so it must work somehow. It’s tempting for me to say that if my place can’t do 2D right how would they manage 3D but maybe 3D would be simpler, hmm….. Sadly in the near to medium term I don’t see a way to export annotated 3D data to our current machine shops so I think it’s a no go. (Don’t get me started on changing vendors, persuading vendors to use something like JT or whatever…)

Mike, I think I was lucky at my last place working defence/aerospace in the UK, the drawing pack was intentionally almost completely separate from the BOM/manufacturing routing. Within reason as long as they met the final drawings they could assemble stuff in whatever order they liked with no changes to the pack to suit a new process etc.

There are a number of ways to get the illustrations or equivalent from CAD, we’re investigating it right now. One software allows us to create an animation of the assembly process, we can then turn that into a step by step word/pdf assembly instruction and/or into an interactive web page showing the assembly process. Instructions can be added to each stage of the animation and automatically populate the word file/web page. It’s still quite a lot of work tho’ although even with out training we’ve created what I think are some pretty impressive examples. Another way we’re looking into is to create work instructions using the CAD system, using the same models but a 2Ddraft document completely separate from the formal drawings.

 

[MikeHalloran]

Managers love animations, until the invoice arrives.

I recommend going easy on that stuff for other reasons. If you demonstrate an ability to remove all the skill from a production job, one fine day you'll be asked to do the same for your own. Or a displaced production person will.




Mike Halloran
Pembroke Pines, FL, USA

 

[ewh]

thundair is ahead of the cuve with mbd. We do some work for Boeing, and the models are easier to work with than a stack of drawings, but come with a copius amount of instruction on their proper interpretation. The only caveat is that you currently need to be using the same software to take full advantage, and even then, most packages aren't yet fully complient with ASME Y14.41. If and when differing systems can read the same information, then mbd will take off, and CAD drawings may go the way of the drawing board.

 

[KENAT]

Mike,

I appreciate your concerns, every time we come up with a procedure/technique/process whatever that simplifies our job the thought crosses my mind.

Unfortunately we have to do something, our drawings generally are not very good and for our assembly drawings the biggest problem (as perceived by me and my colleagues trying to improve standards) is that people try to put assembly instructions on them.

Like I said from what I’ve seen here this leads to a cluttered drawing which still doesn’t really have a full set of assembly instructions and yet, because primarily exploded views have been used, can’t really be used to check that the part was assembled correctly.

I wanted to get some feel for what other people in other industries did which is why I started the thread. Me and the other guys working standards are mostly from aerospace/defence backgrounds. While for most things I’m still inclined to think the way we’re used to doing it was better than what this place does (or as the case may be doesn’t’ do) I’m trying to bear in mind that some of that stuff we did was to meet government requirements, and that in a purely commercial context it may not actually be inherently better/more cost effective.

I was highly skeptical of the animation software when I first saw it, I still have concerns but it’s started to win me over. The one thing I’m not happy with is that while it’s kind of fun to play around with, I consider it something more suited to manufacturing than design but it’s looking like we’ll be doing it if we adopt it.

Ken

 

[zissou]

KENAT; You're an SE user, so you're kind of stuck with some not-so-hot 3D viewers. Depending on the complexity of what your designing for manufacture and if you're using GD&T on these parts - you might want to take a look at eDrawings. We're just starting the process of asking our venders to accept the 3D models as product definition. eDrawings is so much like communicating designs on a napkin, it's not funny. It is very intuitive and easy to use. We use a webpage to host the eDrawings control and model def, so our vendors won't need to download anything. I'm not sure if this is the right forum for this sort of thing, so if this needs moved to another forum, please let me know.

 

[KENAT]

Thanks zissou,

I'm not sure it this is the right forum either, I will say that I saw the demonstration of 3D annotation on V19 at PLM world and wasn't very impressed. From what they said it supports the Y14.41 standard but to me it looked kind of messy and like it would be easy to miss stuff, but hey maybe my brains stuck in 2D and I need to adapt to a fully 3D workflow.

What I think may be on topic is how it relates to assembly 'drawings' I'd be interested to hear from anyone that uses MBD on assemblies. Do you just give them the entire model in its assembled state with some kind of annotation or is there another convention?

Ken

 

[zissou]

Right now, with MBD, we're still in the planning phase. We're looking at two options right now...

Option one is to include the assembly file as a eDrawing .easm file, which can be annotated, etc. This would be the product definiton for the entire assembly - which is usually an inseperable assembly of some sort. If it were for the assembly department - as in instructions - it would be another .easm file annotated with instructions for assembly. A BOM would include hyperlinks to the .eprt files for each seperable component.

Option two is to have individual .eprt files for each component and an .easm file for the finished assemble.

As a side note, when we decided to go to MBD, ease of use was of primary concern. While we're going to try to implement as much of Y14.41 as we can, we're not going to fret about not being able to meet the "letter of the law" so to speak. In the end, we need to communicate what we need to have manufactured and, when it's complete, what we will accept and what will cause us to reject it.

This drive for simple and stupid comes from the fact that some shops are replacing the wise, old machinists, etc with what some call "button pushers". Well, these folks seem to be climbing the corporate ladder and are now foremen, etc. So we need to be as clear and simple as possible when we communicate with them. This may sound elitist or arrogant, but that's not what I want to convey.

Hope that helps.

 

[thundair]

Ken
Our annotation is tied to assy's & subassy's, and then in our case we have a final assy tolerance requirement.

We can "open in a new window" any of these subassy's and complete the requirements.

The shop has limited licenses basically readers, to capture any part or product and extract dimensions from there.

Some of them do a image capture to assign it to a builder and some just leave it on the screen.


QA uses the final assy tolerances and print out the results for sign off.

I am encouraging our guys to use .xml as it allows you to manipulate and no show parts to get a good view of the MBD requirements. Also it is a free download...

http://www.3ds.com/3dxml

Cheers

 

[KENAT]

Just looking in ASME Y14.5M on another matter and noticed that 1.4 e says "The drawing should define a part without specifying manufacturing methods."

So long as you accept that 'part' can refer to an assembly as well as individual component/piece part then I guess this answers the question.

ASSEMBLY DRAWINGS SHOULD NOT GIVE ASSEMBLY INSTRUCTIONS!

Or if they do you can't claim they're to ASME Y14.5M.

Comments???