GlossaryKind of term: Manufacturing termDXF and DWG
What are DXF and DWG?
DXF and DWG are CAD formats that usually hold a 2D drawing or contour, widely used for cutting sheet; depths and requirements are often missing.
DWG is the native file format of a widely used CAD package; DXF is its exchange counterpart, in text or binary form, which nearly every CAD and CAM system reads. Both hold lines, arcs, polylines, splines, text, dimensions and blocks, organised in layers. They can also hold 3D geometry, but what arrives with a request is usually a 2D drawing or a flat contour, such as the flat pattern of a sheet metal part.
What can go wrong with DXF and DWG?
A DXF file may not state its unit unambiguously: the unit sits in a header variable that some systems leave empty, and the reading system then assumes millimetres or inches. Arcs and splines may be approximated as short line segments on export, and loose, duplicate or open lines cause trouble in cutting or CAM software. A dimension stored as loose lines and text rather than as a dimension entity can only be measured off the geometry. Even a true dimension entity can show overridden text that does not match the geometry.
How do DXF and DWG work in practice?
For laser, plasma or waterjet cutting, a DXF of the flat pattern supplies the contour; thickness, material, quantity and tolerances have to come separately. Whether the flat pattern already allows for the bends depends on how it was made, so ask if the part is bent afterwards. For a milled part with pockets, depths and holes at height, a 2D contour is not enough to price from; ask for a STEP model and the drawing. Check units and scale by measuring a known dimension: a contour in inches or not at full scale gives the wrong blank size and cutting length.
What are DXF and DWG often confused with?
A DXF is not a PDF drawing: the PDF is a rendering of the drawing with its dimensions and requirements, while the DXF holds the geometry as coordinates that cutting or CAM software can use directly. A DXF can also be a full drawing with a title block; whether its geometry is at full scale is then a separate check. Nor is a DXF of a flat pattern a 3D model of the bent part; bend lines, bend radius and bend direction must be supplied separately.
Frequently asked questions
Can I price a milled part from a DXF?
Only a simple one, such as a plate with a profile and through holes, and then with thickness, material and tolerances supplied. For pockets, depths and angled faces, ask for a STEP model with the drawing.
Why is my DXF the wrong size?
Usually the unit or the scale. If your system assumes inches where millimetres were meant, or the drawing is to scale, every dimension is off. Check a known dimension before you use the contour.
What is the difference between DXF and DWG?
DWG is one CAD package's native storage format, DXF the exchange format nearly every system reads. With a request, DXF is usually the practical choice, unless you work in a system that opens DWG directly.