Sheet metal flat pattern

[Anonymous]

I have created a sheet metal part and a flat pattern, however the flat pattern ie development part when dimensioned does not seem correct , for instance the overall length does not seem to take into account the bend allowance.

Material is 2 mm thick carbon steel with internal bend radii of 2 mm.

Inventor allocates a default k factor of .44.

When creating a flat pattern what   should I be using to get the correct figures which will later be exported to a dxf for laser cutting.

[swalton]

The default K-Factor in Inventor Sheetmetal may not match your design needs.  K-Factor is dependent on the material, thickness, punch radius, and die width.  It may also be affected by the material grain direction.  Each time one of these variables changes, a new K-Factor is needed.

The best way to determine the proper K-Factor is to make test bends. See the procedure here: http://sheetmetal.me/formulas-and-functions/k-factor/

You can also talk to your sheetmetal vendor to see what they like to use.

[JDMather]

No Inventor files Attached?

On what data are you determining that dimensions don't "seem correct"?

What is the angle of the 24mm flange?

Is the 24mm the planar distance of the face or is it to the implied intersection with the vertical face?

[johnsonshiue]

Hi! Please share the sheet metal part and share the desirable dimensions. There should be a logical explanation to the behavior you are seeing.

Many thanks!

[Anonymous]

Please find attached sheet metal part.

[Anonymous]

Please find attached part.

I need to make sure that the developed flat pattern is correct. If I assume that for instance using a quick check taking into account the internal bend radius of 2 mm using approx. 3.14 of material (inside only) not

mid plane, then I would expect the 51 mm dimension to be 49.1 mm.

Perhaps I am over complicating things.

[JDMather]

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@Anonymous wrote:
1. Please find attached part.
2. If I assume ...

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1. No file Attached?  Do you see a file attached here?  You must use the web forum interface, not email.

2. The Machinery's Handbook has a very simple formula for this calculation.

[Anonymous]

My apologies.

This is something I need to investigate further, your suggestion of using the bend formula from the machinery handbook is a good idea, once satisfied I would expect a flat pattern using inventor sheet metal to be very similar regarding the development and  although there may be slight differences  I am sure that for general sheet metal work the dimensions will suffice.

Thank you

[johnsonshiue]

Hi! Please attach the file. It has not been attached to any prior reply.

Many thanks!