Having worked with CAD systems for over a decade, I still see STEP and IGES files being used regularly to share CAD data.
From my experience, STEP and IGES are both very popular for sharing CAD data within the industry, but which is better?
Generally, STEP files are more robust than IGES files and can handle data more accurately. STEP files are more reliable and easier to work with than IGES files, making them the preferred choice.
It is very important to have the ability to share CAD with other CAD users who are on a different CAD package. For example, I use Siemens NX but share CAD data with SolidWorks customers regularly. I cannot share my native CAD; having a neutral CAD file such as IGES or STEP allows me to do this.
I prefer STEP files as I handle mission-critical CAD data where precision is fundamental. If I need to share CAD data and cannot access the native CAD files, I will choose STEP files.
In this article, I will look deeper into the differences between STEP and CAD files, answering the following:
- What is a STEP file?
- What is an IGES file?
- What is the difference between STEP and IGES files?
- Which is better, IGES or STEP?
- What are the advantages of STEP files?
- Is it wrong to use IGES files?
- Why is it better to share native CAD data?
- How do I create a STEP or IGES file?
- What do STEP versions AP203, AP214 and AP242 mean?
What Is A Step File?
A STEP file, “Standard Exchange of Product Data, ” is a format used to store 3D model data. It is commonly used in CAD (Computer-Aided Design) programs and other engineering programs to store product CAD data.
It is primarily used as an interchange format when 3D models are being shared between different programs.
A STEP file is a standardised format, meaning it can be read and used by various programs with minimal modifications.
For this reason, STEP files are often the best choice for exchanging models between different CAD/engineering programs. For example, if you have a CAD model designed in SolidWorks but want to share it with a Siemens NX CAD user, you can export your CAD model in the STEP format. The Siemens NX CAD user can import this STEP file to inspect or view the CAD model.
Most significantly, STEP files offer more accuracy than many other file formats since they contain detailed information about the 3D model’s geometry and measurements.
What Is An IGES File?
An IGES file, which stands for “Initial Graphics Exchange Specification”, is a format used to store 3D model data in vector graphics. It is commonly used in CAD (Computer-Aided Design) programs and other engineering programs to store product and CAD data.
IGES files are similar to STEP files in that they can share CAD data between CAD engineers who use different CAD packages. However, unlike STEP files, which are standardised, IGES files are not standardised.
What Is The Difference Between STEP And IGES Files?
As a CAD user, you want to know the difference between STEP and IGES files and, more importantly, which file type you should use when sharing CAD data.
As an experienced engineer in this industry for over a decade, I recommend using STEP files.
Although IGES files are not incorrect, they are mainly used because they have been around for so long and have not gone away. You will get a better-quality CAD import with a STEP file.
STEP files are a standardised format, meaning they can be read and used by various programs with minimal modifications. They contain detailed information about the 3D model’s geometry and measurements, making them more accurate than many other file formats.
On the other hand, IGES files are not standardised and vary between different programs. Generally, IGES files tend to be surface models, which can result in a CAD model with gaps or discrepancies when imported.
When I say that IGES files are not standardised, I mean that they are no longer updated or maintained by a current standard. IGES files were first developed in 1980 to share CAD files. Since 1994 no further developments have been made to IGES files.
On the other hand, STEP files were first developed in 1984 to replace the IGES file. Of course, this proved to be a complex thing to do, and as a result, STEP files branched into different internal standards, for example, AP203, AP214 or AP242.
These standards have been intended for industries such as the Aerospace or Automotive industry. Ultimately, if you share CAD data and someone has not specified a specific standard, any STEP file format will work.
STEP files are still being maintained and are governed by ISO standards.
Because of how STEP files are compiled, the resultant CAD data is more robust with greater accuracy than IGES files.
Which Is Better, IGES Or STEP?
STEP files offer higher accuracy and are standardised, making them better for exchanging models between CAD/engineering programs.
STEP files contain detailed information about the 3D model’s geometry and measurements, meaning there is less room for error when transferring the data from one program to another.
IGES files, on the other hand, are not standardised. If accuracy is important, STEP files should be preferred since they are more reliable when transferring data between different applications.
This does not mean that IGES files are bad or wrong. IGES is still a prevalent format used extensively in the CAD industry.
If given a choice, I recommend STEP files instead of IGES.
What Are The Advantages Of STEP Files?
STEP files offer many advantages over other file formats. One of the main advantages is their accuracy.
STEP files contain detailed and precise information about a 3D model’s geometry and measurements, meaning they can generate highly accurate 3D models with minimal errors.
As mentioned, another advantage is that STEP files are in a standardised format, meaning they can be read and used by various programs with minimal modifications.
This makes them ideal for exchanging models between CAD/engineering programs and sharing 3D models over the Internet or other networks.
Is It Wrong To Use IGES Files?
I want to stress that it is not wrong to use IGES files, but some considerations should be taken into account.
While IGES files can help exchange vector graphics, their lack of standardisation can lead to compatibility issues and inaccuracies when transferring data from one program to another. For example, sometimes, you may find gaps on the edges of parts.
For this reason, STEP files are usually preferred for exchanging models between CAD/engineering programs since they are standardised and offer more accuracy than most other file formats.
However, if you need to exchange vector graphics or models between programs that use the same version of the IGES format, then it may be appropriate to use an IGES file instead.
It is not wrong to use IGES files, but be aware that you will most likely get a better result with STEP files.
Why Is It Better To Share Native CAD Data?
Sharing native CAD data is beneficial for a variety of reasons.
When I talk about native CAD data, I refer to your CAD package’s actual model files, for example, SolidWorks, Pro-Engineer (Creo), Siemens NX or any other CAD system.
Native CAD data contain detailed information about a 3D model’s geometry and measurements that is not available in other file formats.
This means that when the data is shared between different programs, the model’s accuracy can be maintained with zero error.
For example, if you share your SolidWorks model with me, and I open it in SolidWorks, I can view your entire history tree, and your model should be exactly as you left it.
Sharing native CAD data is excellent for sharing models internally with your colleagues; however, when sharing CAD data outside the company, whoever receives your CAD file can edit it and make changes.
If you must control your CAD data and keep track of CAD modifications, then it is not recommended to share native CAD. In this instance, using STEP or IGES files is better.
How Do I Create A STEP Or IGES File?
Creating STEP or IGES files is simple and easy to do.
The first step is to export the model from its native CAD format into a STEP or IGES file.
This can be done in most CAD programs by selecting ‘Export’ from the File menu, then choosing either the STEP or IGES format.
Once the file has been exported, all that is left to do is save the file in its new format.
Below is a screenshot of the STEP export option in Siemens NX.
Go to File> Export >STEP for the following dialogue box.
Then select where you want to save your STEP file to.
What Do STEP Versions AP203, AP214 And AP242 Mean?
STEP versions AP203, AP214 and AP242 are three versions of the STEP (Standard for the Exchange of Product Data) file format. They are each designed to meet specific needs, depending on the nature of the data being exchanged.
STEP AP203 is a version of the STEP file format designed for exchanging 3D models between CAD/engineering programs. It contains detailed information about the 3D model’s geometry and measurements, meaning there is less room for error when transferring the data from one program to another. It contains data such as products, mechanical parts and assemblies, approval revision and geometric data such as wireframes, surface models and faceted surfaces. [source]
STEP AP214 is a version of the STEP file format designed specifically for exchanging product data. It includes everything that AP203 can do as it is built on this protocol but includes extra information such as drawings, colours, and GD&T drawing representation. [source]
Finally, STEP AP242 is a version of the STEP file format designed for exchanging product data and 3D models over networks or the Internet. It is an enhanced version of previous protocols that includes additional features such as digital signatures, manufacturing data, document control, encryption, and security protocols. [source]
Using the latest protocol, STEP AP242 is the better option than the above. However, any STEP protocol will suit your needs if you need to share CAD data as a solid model.
In conclusion, when deciding which file format to use, it is important to consider the project’s specific needs.
STEP files are usually preferred for exchanging models between CAD/engineering programs since they are standardised and offer more accuracy than most other file formats.
However, IGES files are still valid. If you need to exchange vector graphics or models between programs that use the same version of the IGES format, then it may be appropriate to use an IGES file instead.
By sharing native CAD data, you can ensure that your model’s accuracy is maintained and can be transmitted quickly and efficiently without any compatibility issues. However, this is only useful for sharing CAD files internally, as if you share native CAD with an external customer or client, they could edit your CAD data.