Taking a Look at CAD Neutral File Formats
Computer-Aided-Design, or CAD as it is more popularly known, has unequivocally transformed the world of architectural and engineering design. It allows swift creation of designs, easy updates, and exports to the next stage in the production process. A good CAD document will include not just the ‘blueprint’ of the building, machine, or product, but also key information like materials, workflow direction, and more.
Despite the benefits of CAD, the file formats can create challenges because each CAD software program has its own native CAD file format. SolidWorks Autodesk Inventor, PTC Creo, and others will all generate file types that are only readable and usable by their software programs. This means that if a client sends you an AutoDesk Inventor file, you’re out of luck if you were hoping to use it in SolidWorks.
This frustration has gone on for long enough, slowing down design processes, to the point that the industry has started to shift to CAD neutral file formats. These CAD neutral file formats allow for operation between multiple software programs. They break down walls and enable a greater degree of collaboration. Some key CAD neutral formats making waves in the world of computer-aided design include STEP, IGES, 3D PDF, JT, STL, ACIS, PARASOLID, and QIF.
Despite these CAD neutral file formats effectively breaking down walls, not all of them are created equal. Each has unique features and abilities that you should know about when deciding to use CAD neutral file formats for your operations. The two that you’ll want to focus on for their greatest level of interoperability and agility are: STEP and IGES. These are the most thoroughly standardized and the others are not and still retain proprietary nature.
Evolution of CAD Neutral File Formats
But first, it’s important to recognize the history that led to the current environment of CAD neutral file formats. Despite feeling like inherently modern technology, CAD has actually been around for decades. The issues with competing and incompatible CAD file formats have been around since then. Especially back in the early days when it wasn’t easy to simply update a software package, download a new program, or ask for your client/customer/partner to use a different program that they weren’t familiar with.
The very first CAD neutral file format came out of the United States Air Force in the early 1980s, and that’s the aforementioned IGES, which stands for Initial Graphics Exchange Specification. The Air Force had a great incentive in terms of time and expense to make the CAD process more useful in designing its equipment, and so it was developed in-house.
In 1980, the U.S. National Bureau of Standards officially approved IGES as a CAD neutral file format to represent circuits, wireframes, freeform surface, and solid models. Where IGES caught immediate success for its ability to translate and in a neutral way represent two-dimensional (2D) CAD and three-dimensional (3D) CAD models, 3D solid models were unable to really be optimized via IGES.
That shortcoming is partially what gave birth to the next key CAD neutral file format, STEP (or The Standard for the Exchange of Product model data). Recognizing the shortcomings for 3D models from IGES, the leaders behind STEP pushed for this new file format to be optimized for geometric shapes and topologies, and associated features, and even next-level information and data like materials, manufacturing processes, testing modules, and product support.
Because of these features, STEP (which was unveiled in 1984) became the standard to represent 3D solid models and for designs that required the inclusion of geometric and non-geometric data.
Comparing STEP and IGES Based on Their Features
STEP and IGES are both CAD neutral file formats that may be useful for your needs, but they are not completely independent and you may choose one or the other depending on your needs. The best way to identify which one would be best for you is by looking at a comparison of their respective features and offerings:
| Feature / Characteristic | IGES | STEP |
| Ability to import/export 2D CAD files | Yes | Yes |
| Ability to import / export 3D CAD files (3D solid models) | Limited Ability | High Ability |
| Editable Files | Yes | No |
| Continuing Support for File Format | No | Yes |
| Ability to Capture 3D Solid Models | No | Yes |
| Covers product lifecycle from beginning to end? | No | Yes |
| Output Type | Surfaces | A mixture of solids and surfaces |
| Speed | Faster | Slower because of solid meshing |
| User Friendliness | Higher because fewer moving parts | Lower because of higher complexity |
When To Use STEP vs. IGES?
The above table is useful for understanding the differences between IGES and STEP, but it doesn’t necessarily answer which one is the best for you. That choice will come down to your personal needs and preferences: For example, do you need 3D models? Do you prefer faster/easier or slower & more accurate?
Some common decision points when using each of the following formats are the following:
IGES is commonly used by:
- Finite element analysis where you don’t need solids and volumes as a part of the modeling
- Computer-aided engineering (CAE) projects will commonly use IGES as the more commonly accepted language
- Less complex projects where only the surfaces are needed
STEP is commonly used by:
- Projects where retrieving, storing, and sharing archived product data is necessary
- Designs where more complexity is expected and required
- Construction industry designs and engineering
- Files needed for 3D printing, CNC machining, and additive manufacturing
The Next Big Thing in CAD Neutral File Formats
There’s seldom a modern industry or project that doesn’t need to utilize CAD in some way, and so ensuring that’s done in the most efficient and optimal manner is critical. The development of new software programs and file formats has continued for decades, but the goals remain the same: interoperability, common languages, and simplicity in design and collaboration. IGES was the first CAD neutral file format to come along, and then STEP took what had been learned and elevated it to a new level. Chances are, the industry will continue to evolve and these file formats will find new use cases, or perhaps new CAD neutral file formats will emerge. Before making a decision on your file format needs, be sure to consult industry experts who can highlight which ones will work best for your situation.
– IndiaCADworks
