{"id":13574,"date":"2026-08-13T11:39:51","date_gmt":"2026-08-13T03:39:51","guid":{"rendered":"https:\/\/hwleiclaser.com\/?post_type=blogs&p=13574"},"modified":"2026-08-13T11:39:51","modified_gmt":"2026-08-13T03:39:51","slug":"laser-cutting-machine-steel-guide-power-thickness-and-assist-gas","status":"publish","type":"blogs","link":"https:\/\/hwleiclaser.com\/pt\/blogs\/laser-cutting-machine-steel-guide-power-thickness-and-assist-gas\/","title":{"rendered":"Laser Cutting Machine Steel Guide: Power, Thickness and Assist Gas"},"content":{"rendered":"

For steel, power sets the practical thickness ceiling and assist gas sets edge quality: oxygen cuts carbon steel thicker per kilowatt with an oxidised edge, nitrogen cuts stainless clean at higher gas cost. Published thickness charts differ because test conditions differ, not because one is wrong.<\/p>\n

The chart problem: five sources, five different maximums<\/h2>\n

Search “laser cutting machine steel<\/strong> thickness chart” and you get tables that disagree by 30% or more at the same power level. One vendor lists 25 mm carbon steel at 6 kW. Another lists 20 mm. A third lists 30 mm and adds no footnote at all.
\nNone of them are necessarily lying. They are measuring different things.
\nVariables that move a published thickness number without any change in laser power:<\/p>\n

    \n
  1. Beam quality and delivery. Two 6 kW sources with different fibre core diameters and collimation produce different power densities at the focal point. The kilowatt figure on the datasheet describes output at the source, not what reaches the kerf.<\/li>\n
  2. Nozzle diameter and standoff. A larger nozzle passes more gas and tolerates more thickness, at the cost of consumption and precision on thin sheet.<\/li>\n
  3. Assist gas purity. Nitrogen at 99.999% and nitrogen at 99.5% cut differently on stainless. Purity is rarely stated on a marketing chart.<\/li>\n
  4. Material grade and surface condition. Hot-rolled plate with heavy mill scale behaves differently from pickled and oiled sheet of the same nominal thickness. Sulphur content in stainless changes dross behaviour.<\/li>\n
  5. Whether piercing was included. Some charts report the thickness a machine can sever once already cutting. Piercing 25 mm plate is a separate problem, and pierce time can exceed cut time on small contours.
    \n6.Test duty cycle. A single demonstration cut on a cool machine at optimum focus is not eight hours of production with a warm optical train and a shift operator who did not re-focus after a lens change.<\/li>\n<\/ol>\n

    The practical consequence: use published charts to shortlist a power tier, then require a sample cut in your own material before you sign. Any supplier who will not run one on the grade you actually buy has told you something useful.<\/p>\n

    \"Cl\u00e1ssico<\/p>\n

    Maximum thickness is not production thickness<\/h2>\n

    A specification sheet’s maximum thickness is the point at which the machine will get through the material. Production thickness is the point at which it gets through the material at a speed and edge quality that your downstream process accepts, repeatably, on a full sheet.
    \nThe gap between the two is usually one to two material sizes. At the very top of a power tier, several things degrade at once: cut speed drops steeply, dross adhesion increases, kerf widens, and thermal input into the part rises enough to matter on tight-tolerance frames. Small internal features and sharp corners are where this shows up first, because the machine cannot maintain the feed rate the cut parameter set assumes.
    \nA working rule for capacity planning: size the machine so that your highest-volume material sits in the middle third of its thickness range, not the top. If 80% of your work is 6 mm to 12 mm carbon steel, a machine that tops out at 12 mm will do it and will be slow and consumable-hungry doing it.<\/p>\n

    Carbon steel and stainless: what actually changes<\/h2>\n

    The two materials do not simply need different parameters. They need a different cutting mechanism, and that changes the gas contract, the edge you hand to the next operation, and the cost per metre.<\/p>\n\n\n\n\n\n\n\n\n\n\n\n
    Dimension<\/td>\nCarbon steel (oxygen cutting)<\/td>\nStainless steel (nitrogen cutting)<\/td>\n<\/tr>\n
    Cutting mechanism<\/strong><\/td>\nExothermic oxidation adds heat to the cut<\/td>\nInert melt-and-blow, laser supplies all energy<\/td>\n<\/tr>\n
    Effective thickness per kW<\/strong><\/td>\nHigher, because the reaction contributes energy<\/td>\nLower at equal power<\/td>\n<\/tr>\n
    Gas pressure regime<\/strong><\/td>\nLow pressure<\/td>\nHigh pressure<\/td>\n<\/tr>\n
    Gas consumption<\/strong><\/td>\nModest<\/td>\nHigh, main variable cost driver<\/td>\n<\/tr>\n
    Edge appearance<\/strong><\/td>\nGrey-black oxide layer<\/td>\nBright, oxide-free<\/td>\n<\/tr>\n
    Downstream impact<\/strong><\/td>\nOxide must be removed before painting, powder coating or welding<\/td>\nWeldable and paintable as cut<\/td>\n<\/tr>\n
    Typical failure mode at limit<\/strong><\/td>\nSlag adhesion on underside, striation coarsening<\/td>\nDross beads, edge discolouration if purity drops<\/td>\n<\/tr>\n
    Nitrogen alternative on carbon steel<\/strong><\/td>\nPossible, gives a weldable edge, cuts thinner at the same power<\/td>\nNot applicable<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

    That last row is the decision most buyers miss. If your carbon steel parts go straight to welding or coating, cutting them under nitrogen removes a deburring or grinding step. It also costs you thickness capability at the same power, and it raises gas spend substantially. Whether that trade is worth it depends on your labour rate for secondary operations, not on the machine.<\/p>\n

    Choosing assist gas: a five-step sequence<\/h2>\n

    Work through this before you specify a gas supply, because a liquid nitrogen tank and a compressed air system are different capital projects.<\/p>\n

      \n
    1. List your materials by volume, not by variety. The gas decision follows the material you cut most hours per week, not the one that appears on the most drawings.<\/li>\n
    2. Identify the downstream operation for each. Painted, powder coated and welded parts care about oxide. Structural brackets going to assembly usually do not.<\/li>\n
    3. Set an edge-quality specification in words your inspector can apply. “No visible dross detectable by hand” is checkable. “Clean edge” is not.<\/li>\n
    4. Price the gas per cutting hour, not per cylinder. Ask the supplier for consumption at the nozzle diameters your thickness range requires, then multiply by realistic machine uptime. High-pressure nitrogen on thick stainless can rival electricity as a running cost.<\/li>\n
    5. Decide whether compressed air belongs in the mix. On thin sheet, filtered and dried compressed air cuts at low cost and leaves a slightly nitrided edge that is acceptable for many enclosures and brackets. It requires genuine air preparation: an undersized dryer produces intermittent quality problems that get blamed on the laser for months.<\/li>\n<\/ol>\n

      What drives cost per metre<\/h2>\n

      Four inputs dominate, and only one of them is the machine price.<\/p>\n