What File Types to Engrave on a CNC Machine

• 1
  Vector formats: the working set when you engrave on a cnc machine
• 2
  What 3D formats add that 2D files cannot
• 3
  Where engraving geometry breaks down
• 4
  How material changes the file you should send
• 5
  File type compared for engraving

Engraving puts a tool tip through a path. The path is what the CAM system reads, so any file you send has to survive the trip as clean vector geometry. DXF and DWG are the default for 2D engraving because they store lines, arcs, and polylines without a fill model. A single-stroke DXF is the cleanest thing you can send us.

SVG is equally usable. It is text-based, it scales without loss, and it handles bezier curves well, which matters for script lettering and small logos. The catch is units. An SVG with no width and height attributes in millimeters can land ten times too large or too small, and the operator will not always catch it before setup.

PDF sits in a gray area. A true vector PDF exported from Illustrator or Inkscape carries the same paths as a DXF and works fine. A scanned PDF is a raster image wrapped in a document shell. It looks sharp on screen and gives CAM nothing to follow.

Check one thing before you export: convert all text to outlines. Font substitution on our side changes stroke width, and a 1.5 mm character can close up into a blob. Outlined text is geometry and cannot shift.

A DXF tells the tool where to travel. It says nothing about how deep to go. Depth usually lives in the CAM operation, not the file, which is fine for flat engraving at a fixed depth on a flat face.

STEP and IGES are the formats to use when the engraving sits on a curved or angled surface. These are true B-rep solids. The CAM system can project the path onto the actual surface, so a part number wrapped around a Ø40 mm boss keeps even depth instead of fading at the edges.

STL is a mesh, not a solid. It works for engraving on organic shapes and cast surfaces, but the facets introduce small errors. On a coarse STL, a curved letter can show visible flat spots. Ask for a finer tessellation if the text is smaller than 4 mm.

A practical split: send DXF or SVG for flat engraving, STEP for anything on a 3D contour. Sending both is common and costs you nothing.

The limit is the tool, not the file. A typical engraving cutter has a 0.2–0.5 mm tip. A stroke narrower than the tip will not cut cleanly; the tool rubs and burns the surface. Keep minimum line width at 0.15 mm and above for readable results.

Character height matters just as much. Below 1.5 mm, letterforms start to merge on aluminium and most plastics. Our laser marking also bottoms out at 1.5 mm character height. If your drawing calls for 1 mm text, expect to widen the font or switch to a different marking method.

Depth is the third constraint. On a 1 mm thick sheet, a 0.3 mm engraving pass removes a third of the material and can warp the part. On thick plate it is a non-issue.

Sharp internal corners are the last one. A round tool cannot produce a true 90° inside corner. If the file demands one, the CAM engineer has to leave a radius, and the drawing should say so.

Aluminium and brass engrave well. Both cut clean chips, hold a crisp edge, and tolerate Ra 0.8–1.6 μm finishes before or after the mark. DXF at 0.2 mm depth is usually enough for a legible part number.

Stainless 304 and 316 work-harden. A light pass can polish instead of cut, so the depth per pass drops and the number of passes rises. Send STEP if the mark follows a curved surface, because re-fixturing a hardened part for a second setup is expensive.

Plastics are the awkward case. POM and ABS burr easily, and PC can craze around the cut. A wider stroke and a shallower depth of 0.1–0.15 mm give a cleaner result than a fine, deep line.

Titanium and Inconel are slow but predictable. Engraving is a light operation compared with milling, so the file type does not change much. What changes is the time, and time is what the quote reflects.