Short Answer:

In CAD (Computer-Aided Design), different file formats are used to save, share, and open 2D or 3D models. The most common types include native file formats like .DWG, .SLDPRT, .IPT, and neutral formats like .STEP, .IGES, and .STL. Each format has its own purpose and is supported by specific software.

Native formats are used within specific CAD programs, while neutral formats are used to exchange files between different software or for 3D printing. Choosing the correct file format ensures compatibility and preserves design accuracy.

Detailed Explanation:

Types of file formats used in CAD

In mechanical design, CAD files play a central role in designing, editing, sharing, and manufacturing parts and assemblies. Each CAD software creates and supports specific file formats. Some formats store 2D drawings, while others support 3D models, assemblies, or mesh data.

CAD file formats can be mainly classified into two categories:

• Native file formats – specific to a particular CAD software.
• Neutral or standard file formats – used to share models across different platforms.

Let’s understand both categories in simple detail.

Native CAD file formats

These formats are designed to work within a specific CAD software. They usually contain all design data, such as sketches, features, history trees, constraints, and metadata.

1. DWG (.dwg)

• Used in AutoCAD for 2D and 3D drawings.
• Very common for architectural and mechanical designs.

2. DXF (.dxf)

• Another AutoCAD format, used for data exchange in 2D.
• Easily opened in other software like CNC or laser cutting tools.

3. SLDPRT (.sldprt)

• SolidWorks part file format for 3D models.
• Stores feature history, sketches, and dimensions.

4. SLDASM (.sldasm)

• SolidWorks assembly file for multi-part projects.
• Includes references to individual part files.

5. IPT (.ipt)

• Autodesk Inventor part file.
• Contains complete design details for a single part.

6. IAM (.iam)

• Autodesk Inventor assembly file for assembling multiple IPT parts.

7. PRT (.prt)

• Used in software like Creo and NX to store part data.
• Different CAD software may use the same extension but with different internal structures.

8. CATPart (.catpart), CATProduct (.catproduct)

• Used in CATIA software for parts and assemblies respectively.

Neutral or standard CAD file formats

These formats are used for data exchange between different CAD systems. They help in sharing files without losing shape or size information.

1. STEP (.step or .stp)

• Most popular neutral format for 3D CAD data exchange.
• Preserves solid geometry and assembly structure.
• Supported by almost all CAD programs.

2. IGES (.iges or .igs)

• Older neutral format used for sharing 2D and 3D geometry.
• Still used for surfaces and wireframe data.

3. STL (.stl)

• Used mainly for 3D printing.
• Stores mesh data only, not original sketches or features.

4. OBJ (.obj)

• Stores 3D mesh data along with color and texture.
• Used in graphics, animation, and 3D printing.

5. 3MF (.3mf)

• A modern replacement for STL.
• Stores more detailed 3D printing data like materials and colors.

Why different formats are used

• Editing: Native formats store all design features and are best for making changes.
• Sharing: Neutral formats like STEP and IGES are used to share models with clients or across software.
• Manufacturing: STL, DXF, and 3MF are often used in 3D printing, laser cutting, and CAM processes.
• File size and compatibility: Some formats are lightweight and ideal for emailing or fast processing.

Conclusion:

CAD uses various file formats depending on the software and the purpose of the file. Native formats like .SLDPRT, .DWG, or .IPT keep all design features for editing, while neutral formats like .STEP, .IGES, and .STL are used to share and manufacture parts. Understanding the types of CAD file formats helps engineers choose the right one for design, communication, and production, ensuring smooth workflow and compatibility.