sheet metal Flat Pattern bounding box, how to add offset?

SOLIDWORKS How To Questions
1

I’ve learned that my memory will sometimes mix things together to create something that never happened, but I thought that I saw that Solidworks Bounding Box sketch in the sheet metal Flat Pattern Feature could be configured with a custom offset.

The reason is that forces out of my control always add a little to the width and length of the bounding box to account for the skeleton in material usage of the part.

Thanks.

2

Create a sketch in your flat pattern configuration after flat pattern feature. With the bounding box visible, select the bounding box, and offset whatever distance you want. This will update in your drawing when/if you make changes. it will only be a rectangle doing it this way. I don’t know if converting the silhouette/offsetting will result in a non-rectangle/square that automatically updates…I haven’t tried that yet.

3

I’m trying to get bounding box, total cut length and number of pierces for Manufacturing. Right now they think I’m doing to set up Solidworks for them so they can manually add up the length of all the line segments. <()>

And they claim that they cannot use the material usage number from CAD because it doesn’t allow enough material around the perimeter of the bounding box for the skeleton. If I can use the equations editor to add 1/4" to the width and length for example then some more math and get them a mass of material usage.
Alternatively, I can use the calculated bounding box area (with no offset) added to a function of the perimeter of the bounding box to get a very close approximation of what the area would be if some constant was added to the width and length of the bounding box. Either way I need this data as numbers in the equation editor to do this. Right?

There are two cutting length variables that I’d like to add together.

This table shows all the properties but I don’t know where or how to make use of them as inputs to equations.
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4

I was hoping for something a little more automatic. The CAD users are quite overloaded with change saturation and there are other more important changes we’ve been drilling into them.

5

Add 2 more properties named “Skeleton X” “Skeleton Y”. Use equations to add on your skeleton width. Then you can put those values into your drawing notes linking in the new variables.

6

bnemec What is your manufacturing use case here? We do alot of sheet metal and have automated some of it to our factory. I’ve never had a request to offset the boundary. We just send a flat pattern output from SolidWorks that is either laser cut or punched. Bending is done on press brakes or our Savagnini machines.

7

We gave up on providing flat patterns. Every shop uses different tooling and what works for one does not for another. If you are using only one shop, you should be able to adjust the bend radius and k-factor without needing to add offsets (provided they always use the same tooling).

8

I don’t know how logical it is, but maybe
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9

New in 2021…
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10

This is for parts we cut and form inhouse. The dxf is what nesting and CNC break use. This info is for manufacturing support department that is loading costing information into our “ERP system”. I’m talking about estimating material usage, the methods or reasoning of estimating are out of scope for me, I’m just supposed to get the “blank” mass but it must include an extra around the bounding box that SW reports to account for skeleton.

11

For tooled parts we send a translated model and print; dxf just when it’s requested but usually not. Like you stated, what the blank looks like is up to the tool maker or the shop making the parts. In this case we are cutting and bending these parts, the dxf is for laser and break. Getting the bounding box with extra boundary is for estimating material usage.

12

Ok, thank you but I cannot figure out what to put in the equation for the original bounding box width and length. No matter what I try it stays red text and does not resolve.

13

I don’t understand what’s new. The ability to use those values in an equation or adding them to the cut list? We have not yet started using cut list, and don’t know if we need to. Is the property $PRPWLD:“Bounding Box Width” new? That is the variable/property that I’m trying to make use of in the Equations, Global Variables and Dimensions table.

14

How much skeleton do they want? 1/4"? Config then flat with 1/8 added all around, move face. Use that config for bounding box.

15

The equation (Type column) in custom properties is new. Before it was added, you can add custom properties but not do calculations.

You need the cut list to get the bounding box length and width. The property is not new but I don’t see a way to pull it in equations.

16

You can do the same thing in the custom props.
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17

I see, the “equation” option is not in the list for 2019.
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So without that option, I cannot get to that variable you’re using.

18

I figured out a way to get around that, it’s quite complicated but it works:

  1. Make a custom property that references the bounding box length
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  2. Make a global variable that references the custom prop and add 0.25" (the equation will give a warning saying “A potential circular reference” but as long as you don’t use the variable to dim something you should be fine.
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  3. Make a custom prop that references the global variable so you can pull the data.

Another way would be:

  1. Flatten the part.
  2. Make a sketch and convert bounding box edge onto the sketch
  3. Put a driven dim on the converted edge.
  4. Reference that dim in the global variable and add 0.25" to it
  5. Make a custom prop that references the global var.
19

Why not use a fixed “lost material percentage”?
What’s your use for this? To send the information to an ERP so that the ERP consumes dimensions that represent more accordingly to what is nested?

Edit:

The estimating of material usage is to use as a value in an ERP to then have a better accuracy of your overall inventory? I’m missing something here


Edit#2: This is the type of precision that companies often try to reach that is more then likely unneeded. Besides, why is it your task to do this if you’re out of scope, wouldn’t it make more sense to ask the appropriate people to take this into account? Heck, pretty sure the nesting program can do what you require it to, ours does(ProNest)

20

All valid and correct assessments Alex. The methods of estimating material are established and not up for debate right now. The other department takes the overall dimensions of the flat from our print, puts them in a spreadsheet >>> and it tells them material usage (it’s a calculator of (width + C)(length + C)(lbs per sq in of material)) There is a wide range of aspect ratios to our parts so the correction factor is not a simple % overrun, but I could still approximate. The precision does add up considering LYTD usage of 14 ga steel was over 600klbs, 11ga was 1.1mlbs, 7ga was ~1.7mlbs. Problem is the nesting software does a better job on parts that have an ‘L’ shape for example, the actual usage is less than the bounding box without the addendum. The method used to estimate material usage is a bit frustrating for me.
You’re also correct on the nesting software but that is on the computer in the work center for the operator to nest orders, they are not doing the estimating/data entry.

Variables and properties and config properties and cutlist properties at all a bit confusing to me, overly complicated and sometimes cryptic naming. Also a bit frustrating that some are exposed as text even though they are numeric. Anyway I didn’t know it would be so difficult to get SW to put a material usage with skeleton included on the print if the part has a flat pattern in the model.