Much has been written about the advantages of laser cutting, so let us talk about something else — its limits. Understanding the limitations helps you design a part so that it gets made right the first time and without extra cost.
Thickness
A laser works best on thin and medium-gauge metal. As thickness grows, speed drops non-linearly: cutting 10 mm is twice as slow as 5 mm, and 20 mm is far slower than 10. So on thick metal laser cutting becomes uneconomical, and it is wiser to choose plasma or waterjet.
Different metals cut differently: stainless steel and aluminium reflect the beam more strongly than mild steel, so the available thicknesses for them are smaller.
Minimum Hole Size
This is the limitation that surprises people most often. A hole cannot be significantly smaller than the metal thickness — the beam has to pierce the material all the way through, and at a small diameter the metal in the cut zone simply overheats and melts shut. The practical rule: the hole diameter should be no less than the sheet thickness, and preferably slightly more.
In other words, a 3 mm diameter hole in 5 mm sheet cannot be laser cut — it is drilled as a separate operation. If a drawing has many such holes, it is worth planning for this in advance.
Sharp Corners and Thin Webs
In a sharp internal corner the beam lingers longer and the metal there heats up more — the corner comes out melted or with a small radius. So in drawings it is better to draw internal corners with a radius from the start.
Very thin webs between cutouts behave just as badly: they overheat, deform, and on thin metal can simply burn away. For perforation this is the main constraint — the hole pitch cannot be too tight.
Taper and Edge Quality
A laser cut is not strictly perpendicular: on thick metal a slight taper is noticeable — the opening is a little wider at the top than at the bottom. For most parts this does not matter, but for precision fits or parts that mate along the thickness it is worth taking into account.
The edge after laser cutting is clean, but on the beam exit side a small burr sometimes remains — on thick materials it is removed by deburring.
Distortion of Thin Sheet
The laser's heat-affected zone is minimal, but on thin metal with a lot of cuts a part can still warp — the metal accumulates internal stresses. For large thin parts with dense cutting patterns this is handled at the process level: the cutting order is changed or micro-tabs are left in place.
What This Means for Your Drawing
- holes — no smaller than the metal thickness;
- internal corners — with a radius, not sharp;
- webs between cutouts — no thinner than the sheet thickness;
- tight tolerances — only where they are truly needed;
- for thicknesses over 20 mm — consider another cutting technology.
We check these points before starting a job and let you know if anything needs changing. More about the technology is on the metal laser cutting page, and about file preparation in the article how to prepare a DXF drawing.
