【转帖】sheet metal par

yang686526

sheet metal part
when designing a simple one bend angle, is there an advantage in modeling it as a sheet metal part instead of just a part?
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in most cases, not if you don't need a flat pattern.
i had a job designing stampings and hinges for a few years.  since all tooling was made by outside vendors, we rearely needed flat patterns, and there was little advantage in use sheet metal in most cases.  our tooling vendors would not accept customer-generated flat patterns because they had been burned too many times by erroneous blank dimensions.
sometimes it would be necessary to unfold, cut, and refold parts to get proper geometry.  in those cases, sheet metal was needed.
i guess it would depend on what you're trying to accomplish. what is your end goal with the part? if it's an extruded metal part it wouldn't matter, but if you're going to lay it out in a flat pattern, use bend allowances or deductions, etc., then i would think it'd be necessary to create it as a sheet metal part (or convert it to one later).  
yes ... so that it can be flattened. if you won't ever need to flatten it, then no.
also you will have the ability to add design library > forming tool features to a sm part.

if the part is uniform thickness, you can convert it to sheet metal at a later point.
insert
-->sheet metal
   -->bends
my new manager questioned me on this one day and he said that in unigraphics, it was better to make the part a sheet metal part because it would be a smaller file as a sheet metal part.  since i had never heard of that, i thought that i would get your opinion on the matter.
if it is the only part that looks like modeling it in sheet-metal (sm) is the option, then do it.
if other users do not know how to use sm, and your products are not sm, no point in using it (for now).
imo, all of the users at your company learn sm. it has more advantages than not.
chris
solidworks/pdmworks 08 3.1
autocad 08
jwlynn64,
   i rarely start a part off in sheet metal.  i usually intend to convert it, but this does not always happen.  
   eventually, i decide to convert.  i sit there and stare at it for a bit, and i decide how to rip it.  then, i do the sequence described by thetick, above.  often, i flatten it and stress relieve the inside corners, and then bend it, again.
   your part should end up as sheet metal.  your fabricators may want to use your solidworks model.  
                         jhg
i'm going to second the tick about not supplying your vendor with a flat pattern. it's bad practice. things bend differently at different facilities. unfortunately i've had to deal with a few customers that are unfamiliar with sheet metal work. they get a little overzealous to "help us out" and only supply us with a flat pattern drawing that they "developed themselves". argh! finished part drawings only please!!!!!.
anyways, back on the subject, i'd say that the advantages i can think of are
1)if you do need a flat pattern for whatever reason, it's already gonna be prepped for you if you modeled it in sheet metal.
2)it seems just as quick if not a tiny tiny bit quicker to model the part you're talking about in sheetmetal than a normal part (i do have a part template with the sheetmetal feature set up though).

if you are just going for file size.  do your own trial.  make a part, save it, make a copy of that part and add sheet metal.  compare file sizes and see which is smaller.
your manager may be referring to starting in sheet metal so you may need 3 parts (with similar features) to figure out the smallest part file possible.
when modeling your part refer back and forth to the feature statistics under the tools menu as you design. great way to see what features are creating you time and to help evaluate best method.