【转帖】who creates assembly drawings

yang686526

who creates assembly drawings?
our company produces analytical instruments.  each instrument typically has a cabinet made out of painted sheetmetal, a printed circuit board card cage assembly with a mother board, a power supply assembly, and some type of analysis module assembly.  3d models of these sub-assemblies as well as the final assembly are created in our cad package.  step-by-step exploded assembly drawings are created for each of the sub-assemblies as well as the final assembly by the mechanical engineers; sometimes with the help of a draftsman.  creating these drawings can be quite time consuming.  there is a push from the director of engineering to get the manufacturing engineers to work with the draftsman to get the assembly drawings created in order to free up the mechanical engineers to work on new designs.  i was wondering if anyone else out there had tried this scenario; and i am particularly interested in what worked well and what didn't.   
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i have worked places where engineers only gave data and napkin sketches to drafters to create finished drawings for review, which was an extreme.
i have also seen where engineers will do basic layout models and data and let drafters finish-detail the models and create all associated documents for review, which seems more common.
i have heard of places where the engineers have to do everything with the models and documents, which is the other extreme.
depending on your cad software, creation of assembly drawings can be easy or tedious, more info is required.
"art without engineering is dreaming; engineering without art is calculating."
fogleghorn,
   i create assembly drawings as part of my design process.  this allows me to analyze the assembly procedure.  
   assembly must be possible.
   in production, assembly must be efficient.  at the design stage, i sometimes work out assembly and test fixtures.  this often feeds back to my design.  
   i want to implement good dfma procedures.  at the design level, if i generate assemblies and parts lists, i can standardize fasteners and other hardware.  manufacturing is not in control of clearance holes and flange thicknesses.
   sub-assemblies should be modular.  this stuff all is fixed at the design level.  once you do not make it modular, there is nothing production can do.
   once, on a complicated module, i created an arrangement drawing.  i copied this over to start off the assembly drawing.  as i worked up the assembly drawing, i wrote separate assembly instructions.  i made a lot of design modifications as i did this, to make those instructions work.
   if you are designing a highly standardized product, you should be able to automate your design and documentation process.  in solidworks, it is often possible to set up a set of template files which you hack to customer requirements.  assembly drawings would be part of the template, and would require little more than tweaking on a project by project basis.
                            jhg
it is very common for engineers to create the 3d models (if they know how), send to designers/drafters to have drawings created.
i worked for a  few companies that have worked this way. it frees up the engineers for other work.
usually engineers don't have the time or the know-how to create the drawings.
chris
solidworks/pdmworks 08 3.1
autocad 08
we are using solid edge, and we also design with modular/testable sub-assemblies.  our assembly drawings can have up to 100 separate line items on the bill of materials.  our step-by-step assembly drawings can require up to 20 b-size or c-size sheets.
our manufacturing engineering department says that since we (the mechanical engineers) designed the instrument, we are the ones that know how it should go together, and therefore we are best suited for creating the assembly drawings.  i have found that in the amount of time that it takes for me to explain how each exploded view should look, i can create the view myself and place that view on one of the sheets of the assembly drawing.  still, our director of engineering (d of e) wants to off-load this task onto the manufacturing engineers and draftsmen.  i might add that our (d of e) is a software engineer by trade.  
fogleghorn, it almost sounds like you work at the same place as me.
historically we had a mess, a lot of hybrid assembly drawings/assembly work instructions see
fogleghorn, we use solid edge too.  are you sure we aren't in the same office!
beware, while explosions in solid edge are quick to produce - they are not very robust.  if you later swap/change parts in the assembly the explosions often fail.  if you have a bunch of notes etc. attatched to the explosion, and depending how you've done it etc this can be a nightmare.
kenat, probably the least qualified checker you'll ever meet...
kenat, doesn't sound like the same company, but it's pretty close.  our manufacturing engineering department doesn't create any drawings, they want everything on the exploded assembly drawings that are currently produced by mechanical engineering.
"these are very time consuming to make, and because we 'validate' them with the shop floor on several builds can take a long time to get finalized."
this is exactly what we do, and i agree that it can take a long time to get the exploded assembly drawings finalized.
from a selfish plc/project release point of view...
as conventional drawings are faster to produce it can significantly reduce development timescales.
product can be released for manufacture based on the drawings.  (freeing engineering to get on with the next product.)
during initial production assembly processes can be fine tuned by manufacturing and documented however they see fit, be it cad generated exploded view assembly instructions or placards at work stations etc.
we are in an industry where 'time to market' is critical.  if i could persuade them of the above i think it would help.
kenat, probably the least qualified checker you'll ever meet...
fogleghorn,
at my last company we had a situation where the design/mechanical engineers were so busy with the "next big thing", that they would produce part models, take a stab at detailing them (more often then not, incorrectly), and generate an assembly model that usually did not include fasteners, cables, and the myriad of incidental components required to build the device (glue, washers, gaskets, etc...). they would then drop the mess on the manufacturing engineer's desks and they would be left on their own to figure out how to build the product from the bits. this usually involved having a designer come down and help the me's build a machine from which they would produce the assembly drawings/manufacturing instructions. then when the first 5 or so were built, they would fail and the engineers would ask why "insert component here" wasn't installed properly or "insert process here" wasn't followed.
i guess what i am getting at is that the designer knows what was intended a lot better than the me does. before i left i made marginal headway into implementing a process that would require the designers to produce an assembly drawing (all components listed and identified, critical dimensions shown and all other information necessary to describe the product) and the me's would then use this to create their assembly documentation.
the designers should not waste their time telling the assemblers how best to build the product, that is the me's job. they do however have critical information that needs to be given to the me's first, and it is best and quickest communicated in an assembly drawing.
david
my experiences agree with the others... usually design engineering defines the assembly, manufacturing engineering defines the assembly procedures.
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