Mechanical CAD Systems and STL File Production

ImPLANT-STL addresses the problem of transferring 3D model data from Mechanical CAD Systems to PDMS, where the model can be manipulated more easily in the DESIGN module and drawings can be produced via the DRAFT module. Popular Mechanical CAD Systems include:

• CATIA

• Pro/ENGINEER

• I-DEAS

• SolidWorks

• ACIS based systems

• Parasolid based systems

• Unigraphics

• Solid Edge

• CADAM

• ROBCAD

• CADDS5

• AutoCAD.

The output files from some other popular Mechanical CAD Systems, such as Microstation, may be imported into DESIGN using product specific translators.

Most of these Mechanical CAD Systems have the capability to export files in the STL format direct or some other standard format or CAD native format such as IGES, STEP AP203/AP214, etc. Translator programs are available which can read these other export file formats and generate STL files. One such Translator Program is CADfix from ITI TranscenData. The possible routes to generating STL files are shown in below.

Figure 6:1. STL File Input to ImPLANT-STL

The method of production of the STL files is an important factor in minimizing the volume of data that needs to be transferred. Applying the following factors will help to reduce the volume of data:

• All curved parts are approximated as planar faces (triangles) in the process of being exported to the STL file. All STL translator programs offer an approximation/tolerance factor to achieve this. It is very important to control the number of triangles produced, keeping these to the minimum to produce an acceptable model in DESIGN.

• All parts of the model that are not essential should be excluded from the transfer, in particular any internal parts that will not be used in PDMS.

• Many features, such as chamfers, are not needed in PDMS and these also should be excluded from the transfer.