Sheet Metal Part 1

[jwlynn64]

When designing a simple one bend angle, is there an advantage in modeling it as a sheet metal part instead of just a part?

 

[TheTick]

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.

 

[Redline8]

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).

 

[CorBlimeyLimey]

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.

 

[TheTick]

If the part is uniform thickness, you can convert it to sheet metal at a later point.

Insert
-->Sheet Metal
-->Bends

 

[jwlynn64]

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.

 

[ctopher]

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
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[drawoh]

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

 

[ATDENGINEERING]

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).

 

[JD80]

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.

 

[Russell67]

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.

 

[ajack1]

Not really answering the original question and it certainly doesn’t apply to a simple single bend, but it is often worth unfolding a complicated part, I have seen many parts that simply cannot be made when you try to unfold them as the model actually overlaps itself.

 

[hendersdc]

If you make the part as a sheet metal part and send the native file to the manufacturer it saves them time because all they have to do to modify the part for their facility is change the bend deductions rather than recreate the part (if you don't send a native file) or convert it to sheet metal.

 

[uGlay]

I used to hate sheetmetal parts until i completed all the SW tutorials and made a large amount of files for a project, now whenever I need to make a part which WILL be manufactured as bent sheetmetal I am eager to bang it out using SM features from the begginning.

it's definitely a different train of thought than just layer caking a part together. most of my suppliers dont want unfolded views so i dont include them in the prints anymore.

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[jwlynn64]

I made a simple 1" x 1" angle as both a standard part and a sheet metal part. The standard part was 111Kb and the sheet metal part was 154Kb.

I think that I can conclude that there is no reason to make a part sheet metal unless you need a flat patter for it.

If anyone can think of another reason you might want to make all of your parts sheet metal, please let me know.

 

[CorBlimeyLimey]

If anyone can think of another reason you might want to make all of your parts sheet metal, please let me know.

No-one is saying that all parts should be made in SM mode, just the parts which are SM in real life; And even then the SM mode does not have to be used to create the model. However, solid parts which are converted to SM are often larger than parts which are created in SM mode.

But to answer your question:

Sometimes it would be necessary to unfold, cut, and refold parts to get proper geometry. In those cases, sheet metal was needed.

Also you will have the ability to add Design Library > Forming Tool features to a SM part.

Note: Both of the above 'reasons' can be achieved by other means. One of the benefits of SW is that there is usually several ways of creating a part ... but that can also be one of it's shortcomings.

 

[jwlynn64]

Thanks for your reply. I didn't mean that all parts should be made as SM. I guess I didn't articulate that well.

I was just making a statement that I could not find an advantage to use SM for simple parts as my new manager had suggested.

As always, thanks for lending your expertise to the issues brought up in the forum.

 

[uGlay]

by starting out with a sheetmetal feature you can take advantage of the bend tables which have all the bend radii already spec'd for different materials in different tempers. In larger more complicated parts, you can change the bend radii globally and will ensure that your walls remain in the correct location.

By doing it with solids you have to constantly look at your bend table handbook and input in the radii during sketch mode. then if it changes you have to edit several different sketches.

As someone mentioned already, if you cannot unfold your part because it will collide with itself then it is worthless and cannot be manufactured... what's the point.



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[uGlay]

You can also specify all your cuts and through holes to be "linked to thickness" thus saving you time having to input a cut depth every time. So if you change material thickness late in the design process, your features will carry through.

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