What file types are best for CNC machining orders?

1. Core 3D CAD formats for accurate manufacturing

For CNC machining, neutral 3D CAD formats are the most reliable basis for programming and verification. STEP (.step / .stp) is preferred, with IGES (.igs / .iges) as a secondary option. These formats preserve solid geometry, allow precise toolpath generation, and reduce translation risk between different CAM systems.

When your models contain complex contours, organic forms, or multiple mating parts, supplying a high-quality 3D file lets us directly integrate with our CNC machining service workflow. It is particularly effective for parts that require efficient roughing and finishing via CNC milling services or rotational features prepared for CNC turning services. For multi-face or 5-axis parts, 3D data is essential for programming a stable multi-axis machining service route and avoiding geometry misinterpretation.

2. 2D drawings: functional requirements and GD&T

3D data defines shape; a 2D drawing defines intent. We strongly recommend a PDF or CAD drawing that includes dimensions, tolerances, GD&T, threads, surface requirements, and critical datums. This combination prevents ambiguity in quotes and production.

For new designs, pairing 3D models with clear 2D drawings is ideal during CNC machining prototyping, allowing us to validate manufacturability, measurement strategy, and cost drivers early. Functional surfaces that can accept standard finishes may simply specify an as machined surface finish, while corrosion-sensitive aluminum components can call out a defined anodized layer using our CNC aluminum anodizing service.

3. Matching file types to materials and applications

Different materials and applications benefit from precise digital definition to control both machining and inspection.

Corrosion-resistant housings and fluid components in Stainless Steel SUS304 require accurate 3D/2D data to secure sealing, threads, and stability. Lightweight structures and brackets in Aluminum 6061 are highly CAM-friendly and respond well to clean solid models. Connector bodies and precision fittings in Brass C360 or functional plastic components in ABS depend on good model quality for tight fits and repeatability. High-temperature or critical-duty parts in Inconel 718 are particularly sensitive to tolerance stack-up—robust CAD and drawings are non-negotiable.

These good data practices directly support demanding sectors such as Automotive, where PPAP/FAI and repeatability are essential, Industrial Equipment, where complex manifolds and frames must align across assemblies, and Medical Device, where cleanliness, traceability, and precise interfaces are critical.

In summary: use STEP as your primary 3D format, add a clear 2D drawing with functional specifications, and avoid screenshots or incomplete exports. Quality input data is the fastest way to secure accurate quotations, stable machining routes, and reliable parts.