DXF file

A DXF file (Drawing Exchange Format) is an exchange format for vector CAD data, introduced by Autodesk in 1982 together with the first version of AutoCAD. Unlike the native, proprietary DWG format, the structure of DXF is publicly documented, which is why almost every CAD, CAM and graphics program can read and write it.

DXF mainly contains 2D geometry: lines, circles, arcs, polylines, splines, text and dimensions, organized into layers and blocks. The format can also store 3D entities, but in practice it is used almost exclusively for 2D. Files have the .dxf extension, are usually plain text, and exist in many versions tied to AutoCAD releases (for example R12, 2000, 2013 or 2018). Older programs may not be able to read newer versions.

In mechanical engineering, DXF is the standard input for processes that work with a flat contour: laser cutting, waterjet and plasma cutting, CNC punching, 2D milling, engraving and gasket cutting. For sheet metal parts, the flat pattern is exported from the 3D model, and the manufacturer's CAM software turns it into a cutting program. DXF is also used to pass 2D drawings to companies that work in AutoCAD, and to transfer PCB outlines between electrical and mechanical design (ECAD and MCAD).

Send a DXF wherever a part is cut from plate or sheet along a contour: laser-cut blanks, flanges, washers, nameplates, gaskets or parts from plastic sheet. For bent sheet metal parts, the usual practice is to send a DXF of the flat pattern together with a STEP file or a drawing of the formed part, so the manufacturer can recalculate the developed length for their own tooling.

For three-dimensional parts a DXF is not enough; those need a STEP file and a drawing. Nor does a DXF replace a technical drawing for parts with tolerances, threads or surface requirements, because it does not carry that information.

Most problems arise during export. The contour must be closed and free of duplicate lines, otherwise the laser cuts the same path twice or does not finish cutting a hole. Dimensions, borders, text and hatching do not belong on the cutting layer, and engraving or bend lines go on a separate layer. Draw at 1:1 scale and check the units, because a DXF exported in inches will load at the wrong size. Draw the outline at final size: the manufacturer sets the kerf compensation in their CAM program. Some programs break splines into short line segments, so for accurate curves it is better to export true circles and arcs.

With every DXF, state the material, thickness, quantity and edge requirements (deburred, burr-free), and for brushed stainless steel also the grain direction. Discuss very small holes and narrow webs (as a rough guide, anything smaller than the sheet thickness) with the manufacturer in advance. If their software cannot open the file, try exporting to an older DXF version.