Use nitrogen-based cutting for speed and edge quality; use oxygen when thickness is beyond what your laser can cut with nitrogen.
Nitrogen-based cutting is generally preferred whenever material thickness allows. It is extremely fast and leaves a clean, oxide-free edge and effectively no heat-effected zone. But cutting thickness is limited by laser power.
Oxygen cutting is used to cut thick. It can increase maximum thickness on steel by about 40% and reduce burr, but it typically cuts at a third the speed of nitrogen and leaves an oxidized edge that flakes off.
What we provide here is meant to be rules of thumb. There are a lot of factors that impact the absolute maximum thickness a laser can cut, ranging from material purity to head design to operator skill.
At 60kW, lasers can cut carbon steel up to 1.75″ using nitrogen assist gas and up to 3″ using oxygen with a highly skilled operator. For those using general labor or inexperienced operators to operate the laser (common in the US), those thicknesses back down to 1.5″ and 2.75″ respectively.
| Laser Power | Mixed Gas Cutting - Skilled Operator | Oxygen Cutting - Skilled Operator |
|---|---|---|
| 60 kW | 1.75" | 3.00" |
| 40 kW | 1.50" | 2.75" |
| 30 kW | 1.125" | 2.50" |
| 20 kW | 0.875" | 2.25" |
| 15 kW | 0.50" | 2.00" |
| 10 kW | 0.375" | 1.50" |
| 6 kW | 0.25" | 1.25" |
Choose a power level that will allow you to cut 33% thicker than your most common material thicknesses with nitrogen-based assist gas.
Oxygen cutting will provide the capability to cut thicker material when necessary and extremely thick material can always be moved to plasma or flame cutting to avoid “overpowering” your laser.
Choose an enclosed flat laser for high-speed cutting of standard sheet sizes, especially when automation is important.
Choose an open-table laser for applications that focus more on heavy plate than thin sheet metal, large-format material, and applications requiring bevel cutting.
When looking to add a bevel cutting machine, look to ensure the fiber laser structure is specifically designed for bevel, the laser power is high enough to cut through greater thickness when the head is angled, and that you can live with reduced dynamic motion performance.
If you are running at least one full production shift per day, then automation may be of great value. In general, Fairmont customers have found that adding automation to a fiber laser doubles the laser output while reducing labor burden. But it is important to understand that standard laser automation is limited to 5/8″ thick steel in day-in, day-out production.
Material storage tower(s) must be paired with unload/load automation, but solve a different problem. By providing immediate access to a variety of materials, storage towers allow for high-mix laser cutting at nearly the same speed and efficiency as low-mix production. At their greatest efficiency, towers provide access to the volume and mix of material to enable lights-out production.
Fiber lasers can cut nearly all common sheet and plate metals used in fabrication. The major groups are carbon steels, stainless and high-alloy steels, aluminum, and reflective nonferrous metals such as copper and brass.
The material affects cutting speed, maximum thickness, assist-gas selection and edge quality, so the same laser power will not have the same capability across every metal.
Plasma remains a capable and cost-effective process for heavy conductive plate, particularly when initial equipment cost is the primary concern.
High-power fiber lasers cost more to purchase than plasma, but provide major advantages in cutting speed, dimensional accuracy, small-feature capability, and reduced downstream processing. Of these benefits, the most important is cut speed, because it pertains directly to cost per part and, therefore, profitability.
Here at Fairmont, we are laser cutting experts, not plasma experts – so plasma information in this article is sourced from Hypertherm and ESAB.
No. Unfortunately, choosing between high-speed and large capacity is the first choice to make when purchasing a tube laser.
Read the full article to learn more.
Tube-laser power should be matched to wall thickness and tube geometry, not simply maximized. While higher power still results in shorter cut times – tube laser cycle times are more impacted by machine dynamics than flat laser, and too much power can damage the opposite wall of a tube.
Generally speaking, those running thin-wall or small-diameter profiles should consider 6 kW with a possible upgrade to 12 kW. Those running thick wall or large diameter profiles should consider 12kW with a possible upgrade to 20 kW.
On a high-speed tube laser, the speed and acceleration of the chucks dramatically impact overall part cycle times. On these machines, only two chucks are used and they are designed to be lightweight, quick, and maneuverable.
On large profile lasers, the primary objective is supporting massive weight over long lengths. These three and four chuck machines are designed for high weight capacities and allow for zero-scrap cutting.
Automatic bundle loading is usually the best solution for high-speed production of light round, square and rectangular tube. While much slower, stage loading is required for open profiles (C-channel, I-beam, etc.) and provides the weight capacity for large profile machines.
Unloading is equally important. High-speed machines allow for a controlled drop on the offload side, while large capacity machines utilize a chuck on the offload side to place parts onto an offload chain conveyor.
