Can I Engrave Letters With a Mitsubishi CNC Machine?

A Mitsubishi CNC does not have an engraving mode that behaves differently from contour milling. The control reads ISO-standard G-code and moves the spindle along X, Y and Z. A letter is a closed contour of a few millimeters. If the machine can mill a 0.5 mm slot, it can mill an A.

What limits you is not the control brand. It is the smallest radius in the font, the depth you want, and how flat the surface is. A 6 mm tall character with a 0.3 mm stroke width needs a 0.2–0.3 mm tip. At that size, a 0.05 mm error in depth is visible. Depth control matters more than XY accuracy.

Start with vector outlines, not a raster image. Text in SolidWorks, Illustrator or a DXF becomes polylines in CAM. Single-line engraving fonts (often called stick or stroke fonts) give you a centerline path, which is faster and easier to control than pocketing a filled outline.

For filled TrueType fonts, CAM has to offset the outline inward for each pass. Small characters become a lot of short arc moves. Most Mitsubishi controls handle this fine, but keep the tolerance in the CAM output tight. A 0.01 mm chord tolerance on a 1 mm radius arc produces very short segments and can cause feed slowdowns.

Post-processor settings matter. Set the output to the exact control model, because M700V and M80 differ in how they read certain canned cycles. Check that your CAM does not post helical or spiral moves your machine will not accept in that context.

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  Use stroke fonts for speedOne centerline pass, no pocketing, faster cycle time.
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  Check chord tolerance0.01 mm or looser keeps segment count sane on small arcs.
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  Match the postM700V and M80 handle some cycles differently; verify before running.

A 30° or 45° included-angle engraving cutter gives a clean V groove. For fine text, a 0.2–0.5 mm single-flute carbide tool holds a sharper corner than a standard end mill. The trade-off is fragility: a 0.2 mm tip breaks if you push it too hard or plunge straight into the surface.

Depth is where most jobs go wrong. On a flat plate, a 0.05 mm depth variation changes how wide the V groove looks. On a curved or cast surface, you need either a rotary table to orient the face, or a Z-following routine. Mitsubishi controls support macro-based surface following, and that is often worth the setup time.

For readable text, ±0.02 mm depth repeatability is usually enough. If your part has a tolerance of ±0.005 mm on the engraved face, the engraving itself can hold tighter, but the surface flatness sets the floor.

Engraving is a light cut, so the fixture only needs to stop the part from moving and keep it flat. A vacuum plate works well for thin sheet. For small parts, a vise with soft jaws machined to the part profile holds better than clamps, because clamps can lift a corner.

Set Z zero on the actual engraved surface, not on the fixture. If the part sits 0.1 mm off the fixture, that error goes straight into your depth. Touch off on a scrap area or use a tool setter. Then run a test letter on a coupon of the same material before touching the real part.

Thermal drift matters on long runs. A spindle that has been running for two hours is not at the same height as a cold one. Warm up the machine, or check Z zero between batches.

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  Flat beats tightA flat part with light clamping gives more consistent depth than a heavily clamped uneven one.
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  Test on a couponSame material, same tool, same depth. Confirm before the real cut.
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  Warm up firstSpindle growth shifts Z; a 15-minute warm-up removes most of it.

Broken tips are the most common problem. They come from plunging too fast, from a tip that is too small for the depth, or from recutting chips because there is no chip evacuation. Use air blast, not flood coolant, for tiny engraving tools.

Worn or faint characters usually mean the tool has dulled or the depth drifted. A 0.2 mm carbide cutter in aluminum may only last a few hundred characters before the tip rounds. Change it on schedule, not after the letters look bad.

Chatter shows up as a rough edge on the character wall. It comes from too much spindle speed for the tool stick-out, or from a part that is not supported under the engraved area. Shorten the tool holder, or add support under thin sections.

Aluminum 6061 and 7075 engrave cleanly with a sharp V cutter. Brass and copper cut well too, though they tend to burr at the top edge, so a light chamfer pass or a bead blast afterward helps. Stainless 303 and 304 work, but expect shorter tool life and more tendency to work-harden if the tool rubs instead of cutting.

Plastics are different. ABS and POM cut cleanly with a sharp tool and high spindle speed. PMMA (acrylic) can chip or craze around the cut, so keep the depth shallow and the feed steady. Carbon fiber and glass-filled plastics are abrasive and will wear a small cutter fast.

Titanium and Inconel will engrave, but it is slow and expensive at small tool sizes. For those, laser marking is usually the better call. We offer laser marking with a minimum character height of 1.5 mm, which covers most part-number and traceability needs.