stefan.ronnlund@notes.electrolux.fi wrote:
> Are there any "automatic" and easy ways to compensate and make a new STL
> file when you have got your first 3-D file and the first cast tool, which
> will because of metal shrinkage be smaller than your first 3D model?
>
> What programs and services are available to make this second 3D model
> easily? The model has to be exactly as much oversized as the shrinkage of
> the first tool?
>
Commercial tools that I know of are limited to applying (global) scale
factors, or a
(global) surface offset to the CAD model.
While at NRC (www.nrc.ca/imti), we developed a method for automating the
model correction process. The process was:
0 make an initial part-RP model-tool
1 create a FEM model of the part
2 scan the part (laser scanner or other fast digitizing method)
3 - fit the scan data to a STL model of the part
- calculate the deformations required to distort/shrink the features of
the FEM model to match the scan data
- invert the deformations calculated to predict a model shape that would
produces a part with the required shape
4 produce an improved part-RP model-tool
Step 4 was automated by a program running on a workstation.
The good news is:
- the method improves the accuracy of parts produced
- it independent of the part shape, material, or manufacturing process
- its quite automatic
The less good news:
- step 4 typically takes hours to run (for the implementation developed).
For more information on this technology, contact Dr. Jeff Xi (jeff.xi@nrc.ca)
-- Bert van den Berg E-mail: bert@hymarc.com Hymarc Ltd. http://www.hymarc.com 35 Antares Drive Tel: (613) 727-1584 Ottawa, Ontario K2E 8B1 Fax: (613) 727-0441
For more information about the rp-ml, see http://ltk.hut.fi/rp-ml/
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