Limitations of 2D drawings
2D engineering drawings have been a part of the design and manufacturing industry for more than a century now. While 2D drawings still play an important part in the product development process they have various limitations some of which are:

• The manufacturers ability to improve their products' time to market is curtailed.
• 2D drawings do not help manufacturers design better products cheaper and faster in an ever increasing competitive environment.
• Analysis of tolerances and fits is not possible with 2D drawings.
• 2D Assembly drawings are almost always cumbersome to draft, interpret and maintain.

The solution: Move to 3D
Most problems that manufacturers face with 2D drawings can be overcome with the use of 3D models. This is the reason why the use of 2D drawings has been superceded by 3D models and 3D solid modelers. While 2D drawings will never completely disappear from the scene (at least not in the near future), the process of creating 3D models and generating the associative 2D drawing from the 3D model is easier to implement and maintain. Solid modeling has been around for more than a decade and there are multiple CAD systems to cater to the various needs of the 3D modeler (e.g. PTC's Pro/Engineer, SolidWorks, Autodesk's Inventor, UGS' Solid Edge etc...). Some advantages of using 3D models:

• Improved time to market.
• Ease of maintenance of design data (parts, assemblies, drawings).
• Improved interference, tolerance and dimension analysis.
• Combining with motion analysis, stress/strain analysis and others is easier to achive.
• Visual reality allows better visualization of end product at design stage.

The choice of the specific CAD system is upto the designer or the company in question. Some CAD system are bundled with PDM and PLM solutions and other tools to improve productivity and maintenance of the company's design wealth.

Problems in moving to 3D
While the use of 3D models sounds like a good idea, there are various hurdles that need to be surpassed before the advantages are realised. Some of the hurdles that companies may encounter:

• Design/Manufacturing companies have thousands or even hundreds of thousands of drawings still in 2D format. Most of this data is still very important to the company and cannot be neglected while the company looks forward to implementing 3D modeling. The task of converting all this legacy data to 3D would be mind-boggling.
• Manual conversion of all this legacy data would take years to complete.
• While many CAD systems include productivity tools that help designers interactively re-use portions of the legacy drawings while building the 3D model, is a far cry from being a valid and viable solution as the designer is still embroiled in a near manual conversion process. PTC's AutobuildZ for Pro/Engineer and SolidWorks 2D-to-3D are two such tools bundled in with the CAD system itself.
• The process of interpreting the 2D drawing to understand and re-create its 3D counterpart is a tedious one, especially if the drawing is complicated. This process has to be repeated for each drawing encountered.

The Solution: FlexiCAD
Imagecom Inc. has created the FlexiCAD suite of software products that work together to overcome many of the problems associated with the conversion of legacy 2D machine piece part drawings to 3D parametric, feature-based models. With over 10 years of research and development behind the suite, FlexiCAD is the most mature conversion software available in the market. The FlexiCAD Suite is unique in that it includes components that are deployed as Application Service Portals (ASP) as well as desktop CAD tools. The next few paragraphs explain in more detail how FlexiCAD's components help in solving the problems stated above during the 2D-to-3D conversion process.

Drawing healing with the click of a button: FlexiCheck
A large class of drawings in the industry today are present in vectorized formats such as DXF or DWG which were drawn using the 2D drafting tools such as AutoCAD^TM. But then there also exist a large number of drawings that went through the vectorization process after being scanned from paper drawings to a raster format such as TIFF or JPEG. This process of raster to vector conversion usually introduces many errors in the vector format. The geometric entities may be broken or disjoint due to minimum dimension issues, multiple overlapping entities may be created due vector conversion algorithm errors, extraneous entities may be created due to streaks on raster files. Before conversion of these vectorized 2D drawings to 3D models can be done, drawing healing has to be performed. This is where FlexiCheck's geometric algorithms can work their magic.

The purpose of FlexiCheck is to validate the input 2D drawing for drawing errors and discrepancies. Various messages and visualization files are created to aid the modeler in making and drawing corrections that cannot be automatically corrected.

FlexiCheck performs three primary validations. The first validation is on the geometry and the geometric intersections. Some simple geometric errors, such as duplicate and/or overlapping entities are automatically corrected during this check. Geometric errors such as lines not quite connecting or extending too far are left up to the modeler to correct. However, a message with exact number of errors coordinated with a visualization tool in the form of a DXF file utilizing different layers and color schemes, allows the modeler to easily find and correct any such errors.

A second validation step in FlexiCheck will analyze the input drawing views for alignment. Again, a message indicating which views are misaligned will be displayed for the modelers.

The third validation step runs checks across orthographic views check to see if potential features have a match in the matching orthographic views. This validation check is an information check only. Again, a resulting information message and a visualization file will be created from this test. If a feature builds incorrectly for whatever reason, this file can give the modeler insights into why a particular feature is incorrect.

Customize as the software converts: FlexiDesign i+
FlexiDesign is an easy to use, CAD system independent, legacy drawing conversion tool built specifically with the designer in mind. With over a decade of research and development behind it, there are many advantages to using FlexiDesign to help with the conversion process. The following are the most advantageous features:

• FlexiDesign outputs a feature-based, parametric 3D model in the native CAD format.
• In its latest version, FlexiDesign supports the most number of geometric features among all the competitive products available in the market - extrusions, revolves, simple and complex holes (counterbore, countersink, tapped, drill tip angle), fillets and chamfers.
• CAD system independent 2D to 3D conversion process. You only need the CAD system to use the interactive mode or view the output 3D model.
• FlexiDesign plugs in to the CAD system of your choice. Designers can choose the CAD system that suits them best and FlexiDesign will help convert the 2D drawing into a native CAD model in that chosen CAD system. i+ currently plugs-in to the following CAD systems:
  • SolidWorks versions 2001 Plus, 2004, 2005, 2006 (Currently in beta testing)
  • Pro/Engineer 2001, WildFire 1.0, 2.0
  • Unigraphics V18, NX
  • Mechanical Desktop 5.0 and 6.0
  • Autodesk Inventor 8.0 (currently in beta testing)
• FlexiDesign is the only conversion system that provides the designer with an easy to use wizard that lets the designer dictate the design intent of the drawing being converted.
• With choices among completely automated, interactive and combined modes of conversion, the designer can convert varying complexities of drawings with ease.
• Your 3D model is conveniently stored in a CAD system independent, feature-based format should you need to recover the output of your 2D to 3D conversion process.
• Geometric and mathematical rule based algorithms help analyze and process drawing entity relationships to ensure error-free geometric features.
• Support for 1 to 6 orthographic views with partial support for projected/auxiliary views. Automatic view recognition unlike the other products in the market.
• Back project 3D model and quality check with input 2D drawings is available currently in Pro/Engineer.

Test Scenario: Company A with 10,000 drawings To better explain how FlexiDesign's conversion system is the perfect solution to handle legacy 2D drawings, we present to you the example of Company A (name withheld for reasons of privacy). Company A had over 10,000 drawings in store which were present in DWG format. The breakup of these drawings were about 6000 simple, 3000 medium complex and rest were complex. This is in general the average percentage of complexity of drawings in most large enterprises. The following steps were implemented to convert all drawings to parametric, feature-based 3D models in Pro/Engineer WildFire:

• Batch process to convert DWG format to a CAD neutral DXF format for use by FlexiDesign.
• 2D drawing healing by FlexiCheck.
• 2D drawing conversion to 3D model by FlexiDesign i+.
• Quality check to verify completeness and correctness.

The following table gives a comparison of using FlexiDesign i+ versus a complete manual conversion:

FlexiDesign i+