Importing and exporting

The formats we often meet.

Overview of 3D CAD File Formats: Parasolid, STEP, and STL

When working with 3D CAD models, choosing the right file format is essential for ensuring precision, compatibility, and downstream usability.

Parasolid is a high-precision format developed by Siemens, used internally by many CAD systems. It stores exact geometry and is ideal for modeling, simulation, and manufacturing processes where accuracy and editability are critical.

STEP is a standardized, vendor-neutral format widely used for exchanging models between different CAD systems. While it preserves solid geometry well, it can suffer from translation issues and lacks feature history.

STL is a simple format that approximates geometry using triangles. It is well suited for 3D printing and visualization but lacks the detail and accuracy needed for engineering and manufacturing workflows.

Choosing the appropriate format depends on the specific application, system compatibility, and required geometric fidelity.

Why Parasolid Format Is Better Than STEP

Native Geometry Kernel Support
Parasolid is a geometric modeling kernel developed by Siemens and used natively in many CAD systems (e.g., Solid Edge, NX, SolidWorks and Onshape). This ensures a higher fidelity and accuracy when exchanging data between compatible systems, without translation losses.

Retains Feature and History Data
Unlike STEP, which is generally limited to geometry and topology, Parasolid files can retain more advanced modeling information. This includes some feature definitions, face colors, layers, and attributes, making it more suitable for workflows that require richer model intelligence.

Faster File Processing
Parasolid files are typically lighter and faster to load, especially in systems that use the Parasolid kernel. This reduces import/export time and improves performance in collaborative environments.

Better Interoperability Within Parasolid-Based Systems
Since many CAD and CAE applications are built on the Parasolid kernel, transferring data between them in Parasolid format reduces the risk of translation errors and ensures higher geometric consistency.

Higher Precision
Parasolid handles B-rep (boundary representation) geometry with high numerical precision. STEP translations can sometimes introduce tolerance issues or approximations during the conversion process.

More Reliable Boolean Operations
Because Parasolid retains exact definitions of geometric entities, operations like Boolean unions or subtractions tend to be more stable and accurate compared to models imported from STEP.