Laser Cutting Steel
We laser cut steel up to 1/2" thick, and we stock most common grades including general purpose "mild" steel, spring steel, tool steels, AR500, and stainless.
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Cut Quality and Dross
Our fiber laser cuts steel up to 1/2" thick, leaving a clean edge and a dross-free surface that typically removes the need for post-operations for most applications.
Laser cutting steel yields a superior edge finish compared to competing alternatives like plasma, and at a much lower cost compared to water-jet and CNC processes like milling.
Our laser produces clean, dross-free parts in most cases, but some parts can push the limits on what is possible even with a state-of-the-art fiber laser.
The limiting factor affecting cut quality is usually heat - laser cutting thick steel requires a lot of energy and the steel heats significantly during the cut. If the part has a high density of cuts relative to the part size, it can get hot enough to affect the cut quality. For example, see the part pictures below. This is the same part in thicknesses of A36 "mild" steel ranging from 3/16" up to 1/2".
Laser cut 3/16" steel - nitrogen assist gas on our 3kW fiber laser
Laser cut 1/4" steel - at this thickness, we switch to oxygen assist gas to add additional energy to the cut (hence the glassy look on the edge)
Laser cut 3/8" steel - at this thickness, this part starts to exhibit minor "gouging" or "stepping" due to the increased material temperature.
Laser cut 1/2" steel - at this thickness, the density of the cuts on the part causes too much heating.
On the half inch thick cut, notice the discolored top surface of the steel: this is indicative of extreme heating during the cut. Because the material is so thick and the cut features are so small relative to the remaining part area, the cut quality is reduced. For larger parts with fewer small features, the cut quality on half inch steel looks much closer to the edge quality on the 1/4" and 1/2" parts above.
On thick materials (1/4" and above), a safe rule of thumb is to keep the width of small features (like the gear teeth in the parts above) at least as wide as the thickness of the material. i.e. A part cut from half inch should have feature sizes at least a half inch wide and preferably more.
Minimum Hole Sizes
Laser-cut hole sizes are limited by the required pierce area and the heat delivered to the slug and surrounding material. When the laser starts a cut on a small hole, it pierces the material near the center and leads in (see below):
Slug from a hole laser cut out of 1/4" steel.
As shown, the pierce itself takes up a potentially non-trivial amount of space - the pierce size increases as the steel thickness increases.
As a rule of thumb, a minimum hole size equal to the material thickness will always be safe (1/4" hole in 1/4" steel, for example. We can usually cut holes down to half the material thickness, but it isn't always a certainty. We won't attempt holes that are less than half the sheet thickness in diameter.
Minimum Hole Sizes in Laser-Cut Steel:
Clean holes: Min hole size = thickness of the sheet for clean holes
Usually clean holes: Min hole size = half the sheet thickness
To avoid surface scratching on parts, we store each sheet type individually, with OSB or thick cardboard between each sheet. This prevents scratching while picking and storing material.
There may, however, be minor surface scratching on the top or bottom surface of the material. Sometimes metal arrives from the mill with cosmetic scratching, and sometimes moving sheets on and off the laser can produce minor scratches.
If a part needs to be pristine, you can expect it to require some minor post-ops to clean it up.